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Elephant
Bibliographic
Database
www.elephantcare.org
References
Updated October 2007
1.
Bates L.A. and Byrne R.W. 2007. Creative or created: using anecdotes to
investigate animal cognition.Methods 42: 12-21.
Abstract: In non-human animals, creative behaviour occurs spontaneously
only at low frequencies, so is typically missed by standardised
observational methods. Experimental approaches have tended to rely
overly on paradigms from child development or adult human cognition,
which may be inappropriate for species that inhabit very different
perceptual worlds and possess quite different motor capacities than
humans. The analysis of anecdotes offers a solution to this impasse,
provided certain conditions are met. To be reliable, anecdotes must be
recorded immediately after observation, and only the records of
scientists experienced with the species and the individuals concerned
should be used. Even then, interpretation of a single record is always
ambiguous, and analysis is feasible only when collation of multiple
records shows that a behaviour pattern occurs repeatedly under similar
circumstances. This approach has been used successfully to study a
number of creative capacities of animals: the distribution, nature and
neural correlates of deception across the primate order; the occurrence
of teaching in animals; and the neural correlates of several
aptitudes--in birds, foraging innovation, and in primates, innovation,
sociallearning and tool-use. Drawing on these approaches, we describe
the use of this method to investigate a new problem, the cognition of
the African elephant, a species whose sheer size and evolutionary
distance from humans renders the conventional methods of comparative
psychology of little use. The aim is both to chart the creative
cognitive capacities of this species, and to devise appropriate
experimental methods to confirm and extend previous findings.
2.
Bates L.W. and Byrne R.W. 2007. Creative or created: Using anecdotes to
investigate animal cognition.Methods 42: 12-21.
Abstract: In non-human animals, creative behaviour occurs spontaneously
only at low frequencies, so is typically missed by standardised
observational methods. Experimental approaches have tended to rely
overly on paradigms from child development or adult human cognition,
which may be inappropriate for species that inhabit very different
perceptual worlds and possess quite different motor capacities than
humans. The analysis of anecdotes offers a solution to this impasse,
provided certain conditions are met. To be reliable, anecdotes must be
recorded immediately after observation, and only the records of
scientists experienced with the species and the individuals concerned
should be used. Even then, interpretation of a single record is always
ambiguous, and analysis is feasible only when collation of multiple
records shows that a behaviour pattern occurs repeatedly under similar
circumstances. This approach has been used successfully to study a
number of creative capacities of animals: the distribution, nature and
neural correlates of deception across the primate order; the occurrence
of teaching in animals; and the neural correlates of several
aptitudes-in birds, foraging innovation, and in primates, innovation,
social learning and tool-use. Drawing on these approaches, we describe
the use of this method to investigate a new problem, the cognition of
the African elephant, a species whose sheer size and evolutionary
distance from humans renders the conventional methods of comparative
psychology of little use. The aim is both to chart the creative
cognitive capacities of this species, and to devise appropriate
experimental methods to confirm and extend previous findings.
3.
Bradshaw G.A. and Schore A.N. 2007. How elephants are opening doors:
Developmental neuroethology, attachment and social context.Ethology 113:
426-436.
Abstract: Ethology's renewed interest in developmental context coincides
with recent insights from neurobiology and psychology on early
attachment. Attachment and social learning are understood as fundamental
mechanisms in development that shape core processes responsible for
informing behaviour throughout a lifetime. Each field uniquely
contributes to the creation of an integrated model and encourages
dialogue between Tinbergen's four analytical levels: ethology in its
underscoring of social systems of behaviour and context, psychology in
its emphasis on socio-affective attachment transactions, and
neuroscience in its explication of the coupled development of brain and
behaviour. We review the relationship between developmental context and
behaviour outcome as a topic shared by the three disciplines, with a
specific focus on underlying neuroethological mechanisms. This
interdisciplinary convergence is illustrated through the example of
abnormal behaviour in wild African elephants (Loxodonta africana) that
has been systematically observed in human-caused altered social
contexts. Such disruptions impair normative socially mediated
neuroendocrinological development leading to psychobiological
dysregulation that expresses as non-normative behaviour. Aberrant
behaviour in wild elephants provides a critical field example of what
has been established in ex situ and clinical studies but has been
largely absent in wild populations: a concrete link between effects of
human disturbance on social context, and short- and long-term
neuroethology. By so doing, it brings attention to the significant
change in theories of behaviour that has been occurring across
disciplines - namely, the merging of psychobiological and ethological
perspectives into common, cross-species, human inclusive models.
4.
King L.E., Douglas-Hamilton I. and Vollrath F. 2007. African elephants
run from the sound of disturbed bees.Current Biology 17: 832-833.
Abstract: Encroaching human development into former wildlife areas [1]
is compressing African elephants into ever smaller home ranges, causing
increased levels of human-elephant conflict [2]. African honeybees have
been proposed as a possible deterrent to elephants [3]. We have
performed a sound playback experiment to study this hypothesis. We found
that a significant majority of elephants, in a sample of 18 well-known
families and subgroups of varying sizes, reacted negatively -
immediately walking or running away - when they heard the buzz of
disturbed bees, while they ignored the control sound of natural
white-noise. Whether the observed response was the result of individual
conditioning or of learning by social facilitation remains to be
established. Our study strongly supports the hypothesis that bees - and
perhaps even their buzz alone - may be deployed to keep elephants at
bay.
5.
Maple T.L. 2007. Toward a science of welfare for animals in the zoo.J
Appl Anim Welf Sci 10: 63-70.
Abstract: Although the accredited institutions of the Association of
Zoos and Aquariums have all committed to enhancing the welfare of
nonhuman animals, acceptable standards and best practices are still
under debate. Currently, experts from zoos and the field hold widely
divergent opinions about exhibition and management standards for
elephants. Standards and practices for managing nonhuman primates
provide a model for other nonhuman creatures exhibited in zoos and
aquariums. Examining the key issues for primates demonstrates the value
of applying scientific data before promulgating standards. The field of
applied behavior analysis provides a wealth of information to frame the
debate. Animal behaviorists have contributed to an emerging science of
animal welfare, which may provide a foundation for empirical zoo
management, standards, and practices.
6.
Savage V.M. and West G.B. 2007. A quantitative, theoretical framework
for understanding mammalian sleep.Proc Natl Acad Sci U S A. 104:
1051-1056.
Abstract: Sleep is one of the most noticeable and widespread phenomena
occurring in multicellular animals. Nevertheless, no consensus for a
theory of its origins has emerged. In particular, no explicit,
quantitative theory exists that elucidates or distinguishes between the
myriad hypotheses proposed for sleep. Here, we develop a general,
quantitative theory for mammalian sleep that relates many of its
fundamental parameters to metabolic rate and body size. Several
mechanisms suggested for the function of sleep can be placed in this
framework, e.g., cellular repair of damage caused by metabolic processes
as well as cortical reorganization to process sensory input. Our theory
leads to predictions for sleep time, sleep cycle time, and rapid eye
movement time as functions of body and brain mass, and it explains, for
example, why mice sleep approximately 14 hours per day relative to the
3.5 hours per day that elephants sleep. Data for 96 species of mammals,
spanning six orders of magnitude in body size, are consistent with these
predictions and provide strong evidence that time scales for sleep are
set by the brain's, not the whole-body, metabolic rate.
Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA.
van_savage@hms.harvard.edu
7. Savage V.M. and West G.B. 2007. A quantitative, theoretical
framework for understanding mammalian sleep.Proc Natl Acad Sci U S A
104: 1051-1056.
Abstract: Sleep is one of the most noticeable and widespread phenomena
occurring in multicellular animals. Nevertheless, no consensus for a
theory of its origins has emerged. In particular, no explicit,
quantitative theory exists that elucidates or distinguishes between the
myriad hypotheses proposed for sleep. Here, we develop a general,
quantitative theory for mammalian sleep that relates many of its
fundamental parameters to metabolic rate and body size. Several
mechanisms suggested for the function of sleep can be placed in this
framework, e.g., cellular repair of damage caused by metabolic processes
as well as cortical reorganization to process sensory input. Our theory
leads to predictions for sleep time, sleep cycle time, and rapid eye
movement time as functions of body and brain mass, and it explains, for
example, why mice sleep {approx} 14 hours per day relative to the 3.5
hours per day that elephants sleep. Data for 96 species of mammals,
spanning six orders of magnitude in body size, are consistent with these
predictions and provide strong evidence that time scales for sleep are
set by the brain's, not the whole-body, metabolic rate
8.
Schulte B.A., Freeman E.W., Goodwin T.E., Hollister-Smith J. and
Rasmussen L.E.L. 2007. Honest signalling through chemicals by elephants
with applications for care and conservation.Applied Animal Behaviour
Science 102: 344-363.
Abstract: Chemical signals are difficult to fake because they are often
directly associated with phenotype and physiological condition, and
hence likely to be honest signals for intraspecific communication.
Chemical signals may be modified after release by the sender or by the
environment. The proximate and ultimate signal meanings are dependent
not only on the condition of the sender, but also on the physiological
status of the receiver. Understanding the relationships and linkage
among signal modality, signal function and receiver response is an
essential first step before using natural signals for animal care and
conservation. Our studies on chemical communication in Asian and African
elephants combine observational and experimental work in captive and
wild settings to further this understanding. Recent discoveries of
pheromones in Asian elephants and the biochemistry of these compounds
provide strong evidence that such chemical signals are honest indicators
of reproductive status. Chemically identifying the signals and verifying
their functional context with statistically robust behavioural studies
are essential aspects for understanding the communication system.
Additionally, the investigative process of discovering, identifying and
verifying the function of chemical signals among captive elephants
offers safe and stimulating enrichments. The knowledge garnered from
such studies has potential conservation benefits for managing wild
elephant populations. A firm foundation of scientific information is
required for successful behavioural investigations and applied
conservation and enrichment components.
9.
Stoeger-Horwath A.S., Stoeger S., Schwammer H.M. and Kratochvil H. 2007.
Call repertoire of infant African elephants: first insights into the
early vocal ontogeny.J Acoust Soc Am 121: 3922-3931.
Abstract: African savannah elephants (Loxodonta africana) have a complex
acoustic communication system, but very little is known about their
vocal ontogeny. A first approach in ontogenetic studies is to define the
call repertoire of specific age groups. Twelve hundred calls of 11
infant elephants from neonatal to 18 months of age recorded at the
Vienna Zoo in Austria and at the Daphne
Sheldrick's orphanage at the Nairobi National Park, Kenya were analyzed.
Six call types were structurally distinguished: the rumble, the bark,
the grunt, the roar (subdivided into a noisy-, tonal-, and mixed-roar),
the snort, and the trumpet. Generally, within-call-type variation was
high in all individuals. In contrast to adult elephants, the infants
showed no gender-dependent variation in the structure or in the number
of call types produced. Male infants, however, were more vocally adamant
in their suckle behavior than females. These results give a
first insight to the early vocal ontogeny and should promote further
ontogenetic studies on elephants. Due to their vocal learning ability in
combination with the complex fission-fusion society, elephants could be
an interesting model to study the role of imitation in the vocal
ontogeny of a nonprimate terrestrial mammal.
10.
Teixeira C.P., Schetini de Azevedo C., Mendl M., Cipreste C.F. and Young
R.J. 2007. Revisiting translocation and reintroduction programmes: the
importance of considering stress.Animal Behaviour 73: 1-13.
Abstract: It is widely known that the adverse effects of stress must be
considered in animal conservation programmes. However, a full
consideration of how and where stress occurs in animal conservation
programmes has not been undertaken, especially in translocation and
reintroduction programmes. The literature concerning these types of
programmes shows high levels of mortality, despite researchers'
consideration of the effects of stress. However, an analysis of the
literature shows that many conservation biologists have only a
superficial knowledge about stress. For example, most do not understand
the importance of subclinical stress or the fact that the effect of
successive stressors can be additive or accumulative. While most
conservation biologists know that stress is bad for animal health, few
have considered its adverse effects on cognitive abilities, which an
animal needs to survive in the wild (e.g. memory). In this paper we
conclude with suggestions for improving the efficiency of animal
conservation programmes in terms of the number of animals surviving
after reintroduction or translocation. The most important conclusion
from this review of the literature is that there needs to be a greater
interchange of information between animal welfare and animal
conservation scientists.
11.
Valeix M., Chamaillé-Jammes S. and Fritz H. 2007. Interference
competition and temporal niche shifts: elephants and herbivore
communities at waterholes.Oecologia Epub ahead of print.
Abstract: Scarcity of resources may result in high levels of animal
aggregation; interference competition can occur in such a scenario and
play a role in resource acquisition. Here, we test the hypothesis that
animals could minimize interference competition by shifting their
temporal niches in relation to competitors. In Hwange National Park,
Zimbabwe, we monitored waterholes in order to study agonistic
interactions between elephants and other herbivore species. We also used
a long-term data set from a yearly survey of waterhole attendance by
herbivores to evaluate the influence of the presence of elephants on the
use of waterholes by other herbivore species. Our results show that in
drier years, waterholes are crowded with elephants early in the
afternoon. In general, the species most affected by interference
competition with elephants shift their temporal niches at the
waterholes, thus maintaining a constant temporal overlaps
with elephants. The species less affected by interference competition
with elephants show no temporal niche shifts and increase their temporal
overlap with elephants at waterholes, as predicted from a noncompetition
hypothesis. This study provides evidence that interference competition
with a behaviorally dominant large species influences the temporal
niches of smaller species, and suggests that the potential costs
associated with interference between elephants and other herbivores at
waterholes are linked to shifts in diurnal activities rather than
interactions and water acquisition itself.
12.
Wittemyer G., Ganswindt A. and Hodges K. 2007. The impact of ecological
variability on the reproductive endocrinology of wild female African
elephants.Hormones and Behavior 51: 346-354.
Abstract: Non-invasive endocrine methods enable investigation of the
relationship between ecological variation and ovarian activity and how
this impacts on demographic processes. The underlying physiological
factors driving high variation in inter-calving intervals among multi-parous
African elephants offer an interesting system for such an investigation.
This study investigates the relationship between Normalized Differential
Vegetation Index (NDVI), an ecosystem surrogate measure of primary
productivity, and fecal progestin concentrations among wild female
elephants. Matched fecal samples and behavioral data on reproductive
activity were collected from 37 focal individuals during the two-year
study. Linear mixed models were used to explore the relationship between
fecal 5 alpha-pregnane-3-ol-20-one concentrations and the independent
variables of NDVI, calf sex, female age, gestation day, and time since
last parturition. Among both non-pregnant and pregnant females, fecal 5
alpha-pregnane-3-ol-20-one concentrations were significantly correlated
with time-specific NDVI indicating a strong relationship between
ecological conditions and endocrine activity regulating reproduction. In
addition, the age of a female and time since her last parturition
impacted hormone concentrations. These results indicate that the
identification of an individual's reproductive status from a single
hormone sample is possible, but difficult to achieve in practice since
numerous independent factors, particularly season, impact fecal hormone
concentrations. Regardless of season, however, fecal 5
alpha-pregnane-3-ol-20-one concentrations below 1 mu g/g were
exclusively collected from non-pregnant females, which could be used as
a threshold value to identify non-pregnant individuals. Collectively the
information generated contributes to a better understanding of
environmental regulation of reproductive endocrinology in wild elephant
populations, information salient to the management and manipulation of
population dynamics in this species.
13.
Wittemyer G. and Getz W.M. 2007. Hierarchical dominance structure and
social organization in African elephants, Loxodonta africana.Animal
Behaviour 73: 671-681.
Abstract: According to the socioecological framework, transitivity (or
linearity) in dominance relationships is related to competition over
critical resources. When a population is structured into groups, the
intensity of between- versus within-group competition influences the
form and function of its social organization. Few studies have compared
the type and relative intensity of competition at these two levels.
African elephants have well-structured social relations, providing an
exemplary system for such a study. We report on dominance hierarchies
among free-ranging elephants and evaluate the factors that drive their
socioecological structure to lie in a region of the three-dimensional
nepotism/despotism/tolerance space rarely observed among social species;
namely, where non-nepotistic, transitive dominance hierarchies within
groups emerge despite kin-based philopatry and infrequent agonistic
interactions over widely distributed resources. We found significant
transitivity in dominance hierarchies between groups. Dominance
relations among the matriarchs of different social groups were primarily
age based, rather than driven by physical or group size, and group
matriarch rank influenced the dominance relationships among
nonmatriarchal females in the population. Our results suggest that
between-group dominance relationships induce tolerance among group
members, which in combination with high group relatedness, reduces the
benefits of nepotism. We postulate that cognitive abilities and high
risk of injury in contests enhance winner and loser effects,
facilitating the formation of transitive dominance relationships,
despite widely distributed resources over which infrequent competition
occurs. The interplay of cognitive abilities, winner and loser effects,
resource distribution, and within- and between-group dominance
relationships may produce behaviour in other strongly social mammals
that differs from that predicted by a superficial application of current
socioecological models.
14.
Alfa Gambari Imorou S. and Sinsin B. 2006.
Impact of
elephant's behaviour on the dynamic of vegetation in the W-Regional
Park: The case of elephants in the north of Benin. Proceedings
International Elephant Conservation & Research Symposium., 2006, pp.
227-240.
15.
Archie E.A., Moss C.J. and Alberts S.C. 2006. The ties that bind:
genetic relatedness predicts the fission and fusion of social groups in
wild African elephants.Proc Biol Sci 273: 513-522.
Abstract: Many social animals live in stable groups. In contrast,
African savannah elephants (Loxodonta africana) live in unusually fluid,
fission-fusion
societies. That is, 'core' social groups are composed of predictable
sets of individuals; however, over the course of hours or days, these
groups may
temporarily divide and reunite, or they may fuse with other social
groups to form much larger social units. Here, we test the hypothesis
that genetic
relatedness predicts patterns of group fission and fusion among wild,
female African elephants. Our study of a single Kenyan population spans
236 individuals in 45 core social groups, genotyped at 11 microsatellite
and one mitochondrial DNA (mtDNA) locus. We found that genetic
relatedness predicted group fission; adult females remained with their
first order maternal relatives when core groups fissioned temporarily.
Relatedness also predicted temporary fusion between social groups; core
groups were more likely to fuse with each other when the oldest females
in each group were genetic relatives. Groups that shared mtDNA
haplotypes were also significantly more likely to fuse than groups that
did not share mtDNA. Our results suggest that associations between core
social groups persist for decades after the original maternal kin have
died. We discuss these results in the context of kin selection and its
possible role in the evolution of elephant sociality.
16.
Bagley K.R., Goodwin T.E., Rasmussen L.E.L. and Schulte B.A. 2006. Male
African elephants, Loxodonta africana, can distinguish oestrous status
via urinary signals.Animal Behaviour 71: 1445.
Abstract: African elephants are a polygynous species that raise
offspring in a matriarchal society. Unlike females, males disperse,
spend time in mate groups and search for mates when mature. Urinary
chemical signals aid males in detecting reproductively active females. A
preovulatory pheromone has been identified in Asian elephants, Elephas
maximus, but has not yet been experimentally identified in African
elephants. In this study, the goal was to determine whether adult
captive male African elephants can distinguish between urine from
conspecific females in luteal and periovulatory oestrous stages as an
indication that a preovulatory pheromone is released in the urine. Urine
was collected from seven different female African elephants during their
luteal and periovulatory periods of oestrus. Bioassays were conducted
with nine adult male elephants housed at six different facilities. Males
were presented with the two urine types and a control sample once a day
over 3 days to reduce sample novelty, which can result in misleadingly
high responses. All mates showed greater chemosensory responses to the
periovulatory urine by trial 3 with the ability to distinguish the
urines increasing over the 3 days. This is the first experimental
behavioural evidence that African elephants release an oestrous
pheromone in the urine. The ability of the captive male elephants to
discern between the two urine types bolsters the hypothesis that there
is a preovulatory pheromone in African elephants and encourages efforts
to identify it.
17.
Bertschinger H., Delsink A., Kirkpatrick J.F. et al. 2006.
Management of elephant populations in private South African game
reserves with porcine zona pellucida vaccine. 2006 Proceedings
American Association of Zoo Veterinarians, pp. 283-285.
Abstract: Control of African elephant populations has become an absolute
necessity in a number of game reserves in southern Africa. The two main
methods used to control populations so far are culling and
translocation. Culling, besides being regarded as inhumane and
unacceptable in many quarters, is not suitable for smaller populations.
It requires that whole family units are culled simultaneously which
could mean that in reserves with 10 to 50 elephants a considerable
portion, if not the entire population, is killed. As far as
translocation is concerned, limited new space is available for
elephants. The only alternative to the two above options is to control
the rate of reproduction. The porcine zona pellucida (pZP) vaccine has
been used to successfully contracept wild horses and other wildlife
species. Work on the contraception of African elephants was initiated
in the Kruger National Park in 1995 when the potential for using the
porcine zona pellucida (pZP) was investigated. Subsequently the first
field trials on wild elephants were carried out in Kruger and the
results clearly showed that elephants could be contracepted with the pZP
vaccine, although the efficacy achieved was 80%. During these field
trials safety and reversibility werecould be demonstrated. In 2000 an
elephant contraceptive program was initiated at Makalali Private Game
Reserve, RSA, which has become the flagship model for immunocontrol in
African elephants. The preliminary findings have been reported in three
publications.During the first year, all 18 cows that were individually
identified and older than 12 yr of age were treated. During the next 4
yr the number of cows contracepted increased to 23 as young animals were
added to the program. The standard vaccination procedure during the
first year consisted of a primary vaccination (600 μg or 400 μg pZP with
0.5 ml Freund's modified complete adjuvant) followed by boosters (200 μg
pZP with 0.5 ml Freund's incomplete adjuvant) at 3 to 6-wk intervals.
Annual boosters to maintain antibody titers and contraceptive effect
followed. To date, the success rate on cows that have passed
reserve-specific intercalving period of 56 mo has been 100%. The
population stabilized within 3 yr by which time when all cows that had
been pregnant at the time of first vaccination in 2000 had calved. Once
again safety during pregnancy (14 cows pregnant at 2-21 mo gestation
when first treated gave birth to normal healthy calves) as well as side
effects that were limited to occasional lumps at the site of vaccination
could be shown. Following ground darting, behavioral patterns returned
to pre-darting status within 2 days. During 2003 and 2004 most boosters
were administered from a helicopter; whereas, previously they had been
done from a vehicle or on foot. In all cases, drop-out darts were used.
Time taken for vaccination from helicopter take-off to landing was about
30 min (1.5 min per cow; 30 min for total time). This required prior
knowledge of the locations of family units or that an individual in each
unit is radio-collared. Herds settled down much more quickly (1-2 days)
than if darted from the ground. Since then we have vaccinated another
107 elephant cows in eight game reserves. The cow populations have
ranged from 4 to 43. In one of the reserves, Mabula, RSA, two of the
four cows vaccinated have passed the mean intercalving intervals of the
reserve with neither of them producing a calf. Treatment at the
remaining reserves was initiated in 2004 or 2005 and it is too early to
evaluate results. The most difficult reserve in terms of the
vaccination process was Welgevonden, RSA, (35 000 ha) with 43 cows. The
reserve is mountainous and heavily wooded. None of the elephants were
collared and individuals could not be easily identified on the day of
primary vaccination. The total flying time during which individuals
were identified and vaccinated was 4.5 hr. Administration of the first
booster took about 2 hr to locate and vaccinate each cow. Between the
first and second booster the first rains occurred, followed by the
spring flush of the vegetation. By the time the second booster was
attempted late in November, the trees all had foliage. Only half the
cows were located and darted because the elephants were very difficult
to spot under the tree canopies. The valuable lessons we learned from
this were: 1) that helicopter vaccinations should be performed when most
trees are bare, and 2) when larger populations are vaccinated repeatedly
during the first year, one cow in each family unit should be
radio-collared. This makes rapid location of each unit possible and cuts
down on the major cost factor that is flying time. Elephant behavior is
being monitored in all eight reserves where contraception is being
applied. Because most of them have been contracepted recently, only the
data from Makalali is available. The elephants at Makalali have been
monitored intensively almost on a daily basis. To date, no anomalies in
terms of aggressive or indifferent behavior with regards to nursing
time, nursing behavior and calf proximity have been noted. No change in
the cows' social hierarchy has been noted. Since January 2003, a total
of 15 heats were observed in 10 cows (nine in 2003 and six in 2004) with
four mating episodes. For the same period, 38 musth occasions were seen
in five bulls (26 in 2003 and 12 in 2004). These occasions include musth
displayed in the same bull during consecutive days or within the same
musth cycle. The greatest occurrence of musth was recorded in the
largest, dominant bull. Bulls were not observed harassing or separating
cows off from their herds or calves as a result of increased estrous
frequency. Thus, the Makalali program demonstrates that pZP does not
cause herd fragmentation, harassment by bulls, change in rank and other
negative behaviors normally associated with hormonal contraceptives. In
conclusion we feel that it is important to emphasize the following
points: The pZP vaccine can be used successfully to contracept African
elephants The vaccine is safe during pregnancy and has no negative
effect on birth or calf raising It has no side effects other than
occasional swelling at the site of vaccination It is reversible Other
than an increased incidence of heat no behavioral side effects were
seen.
18.
Cerling T.E., Wittemyer G., Rasmussen H.B. et al. 2006.
Stable
isotopes in elephant hair document migration patterns and diet
changes.Proc Natl Acad Sci U S A 103: 371-373.
Abstract: We use chronologies of stable isotopes measured from elephant
(Loxodonta africana) hair to determine migration patterns and seasonal
diet changes in
elephants in and near Samburu National Reserve in northern Kenya. Stable
carbon isotopes record diet changes, principally enabling
differentiation between browse and tropical grasses, which use the C3
and C4 photosynthetic pathways, respectively; stable nitrogen isotopes
record regional patterns related to aridity, offering insight into
localized ranging behavior. Isotopically identified range shifts were
corroborated by global positioning system radio tracking data of the
studied individuals. Comparison of the stable isotope record in the hair
of one migrant individual with that of a resident population shows
important differences in feeding and ranging behavior over time. Our
analysis indicates that differences are the result of excursions into
mesic environments coupled with intermittent crop raiding by the migrant
individual. Variation in diet, quantified by using stable isotopes, can
offer insight into diet-related wildlife behavior.
19.
Clemins P.J. and Johnson M.T. 2006. Generalized perceptual linear
prediction features for animal vocalization analysis.Journal of the
Acoustical Society of America 120: 527-534.
Abstract: A new feature extraction model, generalized perceptual linear
prediction (gPLP), is developed to calculate a set of perceptually
relevant features for digital signal analysis of animal vocalizations.
The gPLP model is a generalized adaptation of the perceptual linear
prediction model, popular in human speech processing, which incorporates
perceptual information such as frequency warping and equal loudness
normalization into the feature extraction process. Since such perceptual
information is available for a number of animal species, this new
approach integrates that information into a generalized model to extract
perceptually relevant features for a particular species. To illustrate,
qualitative and quantitative comparisons are made between the
species-specific model, generalized perceptual linear prediction (gPLP),
and the original PLP model using a set of vocalizations collected from
captive African elephants (Loxodonta africana) and wild beluga whales (Delphinapterus
leucas). The models that incorporate perceptional information outperform
the original human-based models in both visualization and classification
tasks.
20.
Druce H., Pretorius K., Druce D. and Slotow R. 2006. The effect of
mature elephant bull introductions on resident bull's group size and
musth periods: Phinda Private Game Reserve, South Africa.South African
Journal of Wildlife Research 36: 133-137.
Abstract: African elephants have been reintroduced into small, enclosed
reserves in South Africa,many populations being established with orphans
<10 years old.This has resulted in abnormal behaviour in some elephant
populations, which was corrected in Pilanesberg National Park by
introducing older bulls and culling certain problem elephants.In July
2003, three older bulls (29-41 years old) were introduced into Phinda
Private Game Reserve, KwaZulu-Natal, South Africa, in order to normalize
the bull age structure and in an attempt to reduce the abnormally long
musth period of one particular resident bull. These introduced bulls
were monitored intensively after release, as was the resident bull
population, both before and after introduction of the older bulls.The
introduced bulls all came into musth within eleven months
postrelease.The older bulls do not appear to have had any influence on
the musth periods of the oldest resident bull (36 years old at
introduction). Detailed behavioural studies of the effects of management
actions on elephant populations, within small, enclosed reserves provide
information and resources for future management decisions.This study
demonstrates that old bulls can be successfully introduced to very small
areas provided that electrification of the entire perimeter is secure.
Further, the introduction has no detectable medium-term (one year)
effect on the behaviour of a relatively dense population of resident
elephants, and the welfare of the elephants was not greatly affected.
21.
Elzanowski A. and Sergiel A. 2006. Stereotypic behavior of a female
Asiatic elephant (Elephas maximus) in a zoo.J Appl Anim Welf Sci. 9:
223-232.
Abstract: This study recorded daytime behavior of a female Asiatic
elephant at the Municipal Zoo, Wroclaw, Poland, in both an indoor pen
and an outdoor paddock as continuous scan sampling for 140 hr, over 35
days in 1 year. Stereotypic sequences involved bouts of highly
repetitive stereotypic movements and much more variable interbout
behavior. The study found both stereotypic movements, nodding and body
(corpus) swaying, were asymmetric, accompanied by protraction of the
right hind leg and to-and-fro swinging of the trunk. The elephant spent
52% of the daytime in stereotypic movements, 3.5 times the level
reported for females in other zoos' groups. The share of time devoted to
stereotypic behavior was lowest in the summer when the elephant was
regularly released to the paddock and highest in the late fall after she
had stayed in the pen after months of days outside. This suggests that
changes in the management routine enhance stereotypies. Comparing the
summer and winter stable management periods, stereotypies were much more
frequent in the indoor pen than the outdoor paddock, suggesting that the
confinement to a barren pen contributed to the observed levels of
stereotypies. Department of Zoology, University of Wroclaw, Wroclaw,
Poland. elzanowski@biol.uni.wroc.pl
22.
Evans K. 2006. Adolescent male African elephant behaviour. Proceedings
International Elephant Conservation & Research Symposium., 2006, p. 86.
23.
Kandler C., Schwammer H., Becker M. and Fleissner G. 2006.
Chronoethology of African elephants (Loxodonta africana) in Zoological
Gardens. Proceedings International Elephant Conservation & Research
Symposium., 2006, pp. 93-97.
24.
Langbauer W., Philp K., Frydman G. and Galvanek J. 2006. The effect of
human contact on African elephant heart rate. Proceedings International
Elephant Conservation & Research Symposium., 2006, pp. 253-255.
25.
Larke A. and Crews D.E. 2006. Parental investment, late reproduction,
and increased reserve capacity are associated with longevity in humans.J
Physiol Anthropol 25: 119-131.
Abstract: Throughout the living world trade-offs between reproductive
success and longevity have been observed. In general, two extremes of
life history patterning are reported, r- and K-selected species. The
latter tend toward larger body sizes, few offspring from any one
pregnancy, few offspring over the female reproductive span, longer life
spans, and greater parental investment (PI: all efforts and expenses
associated with the production, gestation, post-natal care, feeding, and
protection of young) (e.g., whales, elephants, hominids). r-selected
species tend toward smaller body size, multiple births/litters per
pregnancy, female production of many gametes and offspring over the life
span, and low levels of PI (e.g., most plants, insects, mice). These
differences have significant influences on physiological variation among
human populations.Across human samples, reproductive success (RS: the
number of offspring successfully birthed and reared to reproductive age)
has been reported to vary positively, negatively, and not at all with
longevity of women. This complexity may be in part due to the fact that
both early-life and late-life fecundity are associated with longevity in
women, while total parity seems a poor gauge of female longevity in
humankind. Large variations in associations of RS with longevity in
women suggest that multiple factors may confound this association. One
confounding factor is that among women, RS is largely determined not by
fecundity, but by the quality of PI available to offspring. Among modern
humans, PI is more complex, longer lasting (both relatively and
absolutely), and extensive than for any other ammal. This suggests that
modern human life history is a reflection of the co-evolution of
longevity and extensive PI as part of our species' biocultural
evolution. The need for long-term PI has greatly shaped human
physiological variation and patterns of longevity.
26.
Liang Y., McMeeking R.M. and Evans A.G. 2006. A finite element
simulation scheme for biological muscular hydrostats.J Theor Biol Epub
ahead of print.
Abstract: An explicit finite element scheme is developed for biological
muscular hydrostats such as squid tentacles, octopus arms and elephant
trunks. The scheme
is implemented by embedding muscle fibers in finite elements. In any
given element, the fiber orientation can be assigned arbitrarily and
multiple muscle directions can be simulated. The mechanical stress in
each muscle fiber is the sum of active and passive parts. The active
stress is taken to be a function of activation state, muscle fiber
shortening velocity and fiber strain; while the passive stress depends
only on the strain. This scheme is tested by simulating extension of a
squid tentacle during prey capture; our numerical predictions are in
close correspondence with existing experimental results. It is shown
that the present finite element scheme can successfully simulate more
complex behaviors such as torsion of a squid tentacle and the bending
behavior of octopus arms or elephant trunks.
27.
McComb K., Baker L. and Moss C. 2006. African elephants show high levels
of interest in the skulls and ivory of their own species.Biol.Lett. 2:
26-28.
Abstract: An important area of biology involves investigating the
origins in animals of traits that are thought of as uniquely human. One
way that humans appear unique is in the importance they attach to the
dead bodies of other humans, particularly those of their close kin, and
the rituals that they have developed for burying them. In contrast, most
animals appear to show only limited interest in the carcasses or
associated remains of dead individuals of their own species. African
elephants (Loxodonta africana) are unusual in that they not only give
dramatic reactions to the dead bodies of other elephants, but are also
reported to systematically investigate elephant bones and tusks that
they encounter, and it has sometimes been suggested that they visit the
bones of relatives. Here, we use systematic presentations of object
arrays to demonstrate that African elephants show higher levels of
interest in elephant skulls and ivory than in natural objects or the
skulls of other large terrestrial mammals. However, they do not appear
to specifically select the skulls of their own relatives for
investigation so that visits to dead relatives probably result from a
more general attraction to elephant remains.
28.
Morris S., Humphreys D. and Reynolds D. 2006. Myth, marula, and
elephant: an assessment of voluntary ethanol intoxication of the African
elephant (Loxodonta africana) following feeding on the fruit of the
marula tree (Sclerocarya birrea).Physiol Biochem Zool 79: 363-369.
Abstract: Africa can stir wild and fanciful notions in the casual
visitor; one of these is the tale of inebriated wild elephants. The
suggestion that the African elephant (Loxodonta africana) becomes
intoxicated from eating the fruit of the marula tree (Sclerocarya birrea)
is an attractive, established, and persistent tale. This idea now
permeates the African tourist industry, historical travelogues, the
popular press, and even scholastic works. Accounts of ethanol
inebriation in animals under natural conditions appear mired in
folklore. Elephants are attracted to alcohol, but there is no clear
evidence of inebriation in the field. Extrapolating from human
physiology, a 3,000-kg elephant would require the ingestion of between
10 and 27 L of 7% ethanol in a short period to overtly affect behavior,
which is unlikely in the wild. Interpolating from ecological
circumstances and assuming rather unrealistically that marula fruit
contain 3% ethanol, an elephant feeding normally might attain an ethanol
dose of 0.3 g kg(-1), about half that required. Physiological issues to
resolve include alcohol dehydrogenase activity and ethanol clearance
rates in elephants, as well as values for marula fruit alcohol content.
These models were highly biased in favor of inebriation but even so
failed to show that elephants can ordinarily become drunk. Such tales,
it seems, may result from "humanizing" elephant behavior. School of
Biological Sciences, University of Bristol, Woodland Road, Bristol BS8
1UG, United Kingdom. steve.morris@bristol.ac.uk
29.
Nissani M. 2006. Do Asian elephants (Elephas maximus) apply causal
reasoning to tool-use tasks?J Exp Psychol Anim Behav Process 32: 91-96.
Abstract: Two experiments addressed contradictory claims about causal
reasoning in elephants. In Experiment 1, 4 Asian elephants (Elephas
maximus) were pretrained
to remove a lid from the top of a bucket and retrieve a food reward.
Subsequently, in the first 5 critical trials, when the lid was placed
alongside
the bucket and no longer obstructed access to the reward, each elephant
continued to remove the lid before retrieving the reward. Experiment 2,
which
involved 11 additional elephants and variations of the original design,
yielded similarly counterintuitive observations. Although the results
are open to alternative interpretations, they appear more consistent
with associative learning than with causal reasoning. Future
applications of Fabrean
methodologies (J. H. Fabre, 1915) to animal cognition are proposed.
30.
Norgaard C. 2006. Towards 24 hours of enrichment. Proceedings
International Elephant Conservation & Research Symposium., 2006, p. 260.
31.
Plotnik J.M., de Waal F.B. and Reiss D. 2006. Self-recognition in an
Asian elephant.Proc Natl Acad Sci U S A 103: 17053-1770.
Abstract: Considered an indicator of self-awareness, mirror
self-recognition (MSR) has long seemed limited to humans and apes. In
both phylogeny and human ontogeny, MSR is thought to correlate with
higher forms of empathy and altruistic behavior. Apart from humans and
apes, dolphins and elephants are also known for such capacities. After
the recent discovery of MSR in dolphins (Tursiops truncatus), elephants
thus were the next logical candidate species. We exposed three Asian
elephants (Elephas maximus) to a large mirror to investigate their
responses. Animals that possess MSR typically progress through four
stages of behavior when facing a mirror: (i) social responses, (ii)
physical inspection (e.g., looking behind the mirror), (iii) repetitive
mirror-testing behavior, and (iv) realization of seeing themselves.
Visible marks and invisible sham-marks were applied to the elephants'
heads to test whether they would pass the litmus "mark test" for MSR in
which an individual spontaneously uses a mirror to touch an otherwise
imperceptible mark on its own body. Here, we report a successful MSR
elephant study and report striking parallels in the progression of
responses to mirrors among apes, dolphins, and elephants. These
parallels suggest convergent cognitive evolution most likely related to
complex sociality and cooperation. Living Links, Yerkes National Primate
Research Center, and Department of Psychology, Emory University, 532
North Kligo Circle, Atlanta, GA 30322, USA.
32.
Reznikova Zh.I. 2006. The study of tool use as the way for general
estimation of cognitive abilities in animals.Zh Obshch Biol 67: 3-22.
Abstract: Investigation of tool use is an effective way to determine
cognitive abilities of animals. This approach raises hypotheses, which
delineate limits of animal's competence in understanding of objects
properties and interrelations and the influence of individual and social
experience on their behaviour. On the basis of brief review of different
models of manipulation with objects and tools manufacturing (detaching,
subtracting and reshaping) by various animals (from elephants to ants)
in natural conditions the experimental data concerning tool usage was
considered. Tool behaviour of anumals could be observed rarely and its
distribution among different taxons is rather odd. Recent studies have
revealed that some species (for instance, bonobos and tamarins) which
didn't manipulate tools in wild life appears to be an advanced tool
users and even manufacturers in laboratory. Experimental studies of
animals tool use include investigation of their ability to use objects
physical properties, to categorize objects involved in tool activity by
its functional properties, to take forces affecting objects into
account, as well as their capacity of planning their actions. The
crucial question is whether animals can abstract general principles of
relations between objects regardless of the exact circumstances, or they
develop specific associations between concerete things and situations.
Effectiveness of laboratory methods is estimated in the review basing on
comparative studies of tool behaviour, such as "support problem", "stick
problem", "tube- and tube-trap problem", and "reserve tube problem".
Levels of social learning, the role of imprinting, and species-specific
predisposition to formation of specific domains are discussed.
Experimental investigation of tool use allows estimation of the
individuals' intelligence in populations. A hypothesis suggesting that
strong predisposition to formation of specific associations can serve as
a driving force and at the same time as obstacle to animals' activity is
discussed. In several "technically gifted" species (such as woodpecker
finches, New Caledonian crows, and chimpanzees) tool use seems to be
guided by a rapid process of trial and error learning. Individuals that
are predisposed to learn specific connections do this too quickly and
thus become enslaved by stereotypic solutions of raising problems.
33.
Shannon G., Page B.R., Duffy K.J. and Slotow R. 2006. The role of
foraging behaviour in the sexual segregation of the African
elephant.Oecologia Epub.
Abstract: Elephants (Loxodonta africana) exhibit pronounced sexual
dimorphism, and in this study we test the prediction that the
differences in body size and sociality are significant enough to drive
divergent foraging strategies and ultimately sexual segregation. Body
size influences the foraging behaviour of herbivores through the
differential scaling coefficients of metabolism and gut size, with
larger bodied individuals being able to tolerate greater quantities of
low-quality, fibrous vegetation, whilst having lower mass-specific
energy requirements. We test two distinct theories: the scramble
competition hypothesis (SCH) and the forage selection hypothesis (FSH).
Comprehensive behavioural data were collected from the Pongola Game
Reserve and the Phinda Private Game Reserve in South Africa over a
2.5-year period. The data were analysed using sex as the independent
variable. Adult females targeted a wider range of species, adopted a
more selective foraging approach and exhibited greater bite rates as
predicted by the body size hypothesis and the increased demands of
reproductive investment (lactation and pregnancy). Males had longer
feeding bouts, displayed significantly more destructive behaviour (31%
of observations, 11% for females) and ingested greater quantities of
forage during each feeding bout. The independent ranging behaviour of
adult males enables them to have longer foraging bouts as they
experience fewer social constraints than females. The SCH was rejected
as a cause of sexual segregation due to the relative abundance of low
quality forage, and the fact that feeding heights were similar for both
males and females. However, we conclude that the differences in the
foraging strategies of the sexes are sufficient to cause spatial
segregation as postulated by the FSH. Sexual dimorphism and the
associated behavioural differences have important implications for the
management and conservation of elephant and other dimorphic species,
with the sexes effectively acting as distinct "ecological species".
34.
Shannon G., Page B.R., Duffy K.J. and Slotow R. 2006. The consequences
of body size dimorphism: Are African elephants sexually segregated at
the habitat scale?Behaviour 143: 1145-1168.
Abstract: Sexual segregation is a commonly observed phenomenon in
dimorphic ungulates, which has been categorised into two distinct
components: social segregation and habitat segregation. In this study we
investigated whether elephants were sexually segregated at the habitat
scale. The locations of 12 family groups and 16 males, in three distinct
populations were recorded over a period of 2.5 years. Selection ratios
were calculated for each habitat type and a Kendall's coefficient of
concordance was used for the analyses. The habitat and foraging
preferences were firstly tested for concordance within sex, and then
between the sexes. Female habitat preferences showed significant
concordance across all reserves and they also exhibited strong
concordance in their summer foraging preferences. Their weakest
association with habitat and foraging preference was during winter,
which may be related to resource scarcity. Males exhibited significant
concordance in their habitat preferences in two out of the three
reserves. They had their weakest associations in the summer months and
this may be linked to avoidance of other males in musth and the
abundance of forage. There were no significant differences in habitat
preference between males and females and it is likely that individual
preferences vary as much within sex as between sexes. Differential
habitat utilisation does not appear to be driving sexual segregation in
elephants and it is postulated that sociality, divergent reproductive
strategies and foraging behaviour at the plant scale play a more
significant role. The results of this study highlight the importance of
scale in elucidating the mechanisms involved in sexual segregation.
35.
Shannon G., Page B.R., Duffy K.J. and Slotow R. 2006. The role of
foraging behaviour in the sexual segregation of the African
elephant.Oecologia 150.
Abstract: Elephants (Loxodonta africana) exhibit pronounced sexual
dimorphism, and in this study we test the prediction that the
differences in body size and sociality are significant enough to drive
divergent foraging strategies and ultimately sexual segregation. Body
size influences the foraging behaviour of herbivores through the
differential scaling coefficients of metabolism and gut size, with
larger bodied individuals being able to tolerate greater quantities of
low-quality, fibrous vegetation, whilst having lower mass-specific
energy requirements. We test two distinct theories: the scramble
competition hypothesis (SCH) and the forage selection hypothesis (FSH).
Comprehensive behavioural data were collected from the Pongola Game
Reserve and the Phinda Private Game Reserve in South Africa over a
2.5-year period. The data were analysed using sex as the independent
variable. Adult females targeted a wider range of species, adopted a
more selective foraging approach and exhibited greater bite rates as
predicted by the body size hypothesis and the increased demands of
reproductive investment (lactation and pregnancy). Males had longer
feeding bouts, displayed significantly more destructive behaviour (31%
of observations, 11% for females) and ingested greater quantities of
forage during each feeding bout. The independent ranging behaviour of
adult males enables them to have longer foraging bouts as they
experience fewer social constraints than females. The SCH was rejected
as a cause of sexual segregation due to the relative abundance of low
quality forage, and the fact that feeding heights were similar for both
males and females. However, we conclude that the differences in the
foraging strategies of the sexes are sufficient to cause spatial
segregation as postulated by the FSH. Sexual dimorphism and the
associated behavioural differences have important implications for the
management and conservation of elephant and other dimorphic species,
with the sexes effectively acting as distinct "ecological species".
36.
Shoshani J., Kupsky W.J. and Marchant G.H. 2006. Elephant brain. Part I:
gross morphology, functions, comparative anatomy, and evolution.Brain
Res Bull 70: 124-157.
Abstract: We report morphological data on brains of four African,
Loxodonta africana, and three Asian elephants, Elephas maximus, and
compare findings to literature. Brains exhibit a gyral pattern more
complex and with more numerous gyri than in primates, humans included,
and in carnivores, but less complex than in cetaceans. Cerebral frontal,
parietal, temporal, limbic, and insular lobes are well developed,
whereas the occipital lobe is relatively small. The insula is not as
opercularized as in man. The temporal lobe is disproportionately large
and expands laterally. Humans and elephants have three parallel temporal
gyri: superior, middle, and inferior. Hippocampal sizes in elephants and
humans are comparable, but proportionally smaller in elephant. A
possible carotid rete was observed at the base of the brain. Brain size
appears to be related to body size, ecology, sociality, and longevity.
Elephant adult brain averages 4783 g, the largest among living and
extinct terrestrial mammals; elephant neonate brain averages 50% of its
adult brain weight (25% in humans). Cerebellar weight averages 18.6% of
brain (1.8 times larger than in humans). During evolution,
encephalization quotient has increased by 10-fold (0.2 for extinct
Moeritherium, approximately 2.0 for extant elephants). We present 20
figures of the elephant brain, 16 of which contain new material.
Similarities between human and elephant brains could be due to
convergent evolution; both display mosaic characters and are highly
derived mammals. Humans and elephants use and make tools and show a
range of complex learning skills and behaviors. In elephants, the large
amount of cerebral cortex, especially in the temporal lobe, and the
well-developed olfactory system, structures associated with complex
learning and behavioral functions in humans, may provide the substrate
for such complex skills and behavior.
37.
Stoeger-Horwath A.S., Schwammer H.M., Kratochvil H. and Stoeger S. 2006.
Infant talk - first insights into the vocal ontogeny of elephants
(Loxodonta africana). Proceedings International Elephant Conservation &
Research Symposium., 2006, pp. 178-181.
38.
Tresz H. 2006. Behavioral management at the Phoenix Zoo: New strategies
and perspectives.Journal of Applied Animal Welfare Science 9: 65-70.
Abstract: It all started with a seemingly simple decision to re-evaluate
and document the Phoenix Zoo's behavioral management protocol. The
purpose of this project was to present proactive standards for the care
and psychological well-being of our living collection, while meeting or
exceeding the guidelines of the Animal Welfare Act. Preparing the
protocol was a catalyst to re-evaluate the zoo's philosophy and
application of behavioral management. It suggested a restructuring of
collection management and the rethinking of future goals and practices.
Gradually, the process became more focused and organized. Behavioral
enrichment, training, animal behavior issues, and exhibit architecture
were embraced as essential components for providing quality of life.
Staff from all levels worked side-by-side on assignments. Our way of
thinking and working was changing.
39.
Vidya T.N.C. and Sukumar R. 2006. Social organization of the Asian
elephant (Elephas maximus) in southern India as inferred from
microsatellite DNA. Proceedings International Elephant Conservation &
Research Symposium., 2006, pp. 214-216.
40.
Viljoen J.J., Reynecke H.C., du Toit J.T. and Langbauer W.R. 2006.
Elephant family groups may cause little environmental damage in the
Kruger Park. Proceedings International Elephant Conservation & Research
Symposium., 2006, p. 274.
41.
Wall J., Douglas-Hamilton I. and Vollrath F. 2006. Elephants avoid
costly mountaineering.Current Biology 16: 527-529.
42.
Weidner E.B., Isaza R., Galle L.E., Barrie K. and Lindsay W.A. 2006.
Medical management of a corneal stromal abscess in a female Asisan
elephant (Elephas maximus).Journal of Zoo and Wildlife Medicine 37:
397-400.
43.
Weissenböck N.M. 2006. How do elephants deal with various climate
conditions? Previous results, recent data and new hypotheses.
Proceedings International Elephant Conservation & Research Symposium.,
2006, pp. 217-224.
44.
Wittemyer G. and Getz W.M. 2006. A likely ranking interpolation for
resolving dominance orders in systems with unknown
relationships.Behaviour 143: 909-930.
Abstract: In many animal systems agonistic interactions may be rare or
not overt, particularly where such interactions are costly or of high
risk as is common for large mammals. We present a technique developed
specifically for resolving an optimized dominance order of individuals
in systems with transitive (i.e. linear) dominance relationships, but
where not all relationships are known. Our method augments the widely
used I&SI method (de Vries, 1998) with an interpolation function for
resolving the relative ranks of individuals with unknown relationships.
Our method offers several advantages over other dominance methods by
enabling the incorporation of any proportion of unknown relationships,
resolving a unique solution to any dominance matrix, and calculating
cardinal dominance strengths for each individual. As such, this method
enables novel insight into difficult to study behavioural systems.
45.
Bertelsen M.F., Bojesen M. and Olsen K.E.P. 2005. Fatal enterocolitis in
two Asian elephants (Elephas maximus) caused by Clostridium
difficile. 2005 Proceedings AAZV, AAWV, AZA Nutrition Advisory
Group, pp. 66-67.
Abstract: Altered behavior, anorexia and listlessness were observed in
four of five adult captive female Asian elephants (Elephas maximus).
Two animals recovered, while two died after 2 days. The dead elephants
were subjected to post mortem examination including histopathology,
demonstrating fibrinonecrotic enteritis and colitis. Clostridium
difficile was isolated from both dead elephants and from the feces
of the two surviving affected animals, and identified by selective
cultivation and PCR identification. All isolates had the tcdA and
tcdB toxin genes and were positive in a toxigenic culture assay.
C. difficile toxin from the intestinal content of one of the
fatal cases was demonstrated using cell-culture based cytotoxin assays.
Clostridium perfringens type A and Clostridium septicum
were also isolated from both dead animals. Although C. perfringens
has been associated with ulcerative enteritis in an elephant,1
in this case these isolates likely are incidental, as C.
perfringens enterotoxin was not demonstrated, and as C.
septicum is well known for producing rapid post mortem overgrowth.
Amplified fragment length polymorphism typing, showed that the C.
difficile isolates recovered from the outbreak, all had the same
fingerprint profile, indicating that all four elephants were affected by
the same bacterial clone. These findings appear to be the first to
demonstrate that C. difficile may cause enterocolitis in
elephants. The results emphasize the need to regard this organism as
potentially dangerous for elephants. Although there was no prior
exposure to antibiotic agents in this case, caution is recommended when
treating elephants with antibiotics, as this may trigger C.
difficile induced enterocolitis in other species, most notably
humans and horses.2
LITERATURE CITED
1 Bacciarini, L.N., O. Pagan, J. Frey, and A. Grone. 2001. Clostridium
perfringens beta2-toxin in an African elephant (Loxodonta africana)
with ulcerative enteritis. Vet. Rec. 149: 618-20.
2 Songer, J.G. 1996. Clostridial enteric diseases of domestic animals.
Clin. Microbiol. Rev. 9: 216-234.
46.
Bradshaw G.A., Schore A.N., Brown J.L., Poole J.H. and Moss C.J. 2005.
Elephant breakdown.Nature 433: 807.
47.
Clemins P.J., Johnson M.T., Leong K.M. and Savage A. 2005. Automatic
classification and speaker identification of African elephant (Loxodonta
africana) vocalizations.J Acoust Soc Am. 117: 956-963.
Abstract: A hidden Markov model (HMM) system is presented for
automatically classifying African elephant vocalizations. The
development of the system is motivated by
successful models from human speech analysis and recognition.
Classification features include frequency-shifted Mel-frequency cepstral
coefficients (MFCCs)
and log energy, spectrally motivated features which are commonly used in
human speech processing. Experiments, including vocalization type
classification and
speaker identification, are performed on vocalizations collected from
captive elephants in a naturalistic environment. The system classified
vocalizations with accuracies of 94.3% and 82.5% for type classification
and speaker identification classification experiments, respectively.
Classification accuracy, statistical significance tests on the model
parameters, and qualitative analysis support the effectiveness and
robustness of this approach for vocalization analysis in nonhuman
species.
Speech and Signal Processing Laboratory, Marquette University,
Milwaukee, Wisconsin 53233-1881, USA. patrick.clemins@marquette.edu
48.
Cushman S.A., Chase M. and Griffin C. 2005. Elephants in space and
time.Oikoso 109: 331-341.
Abstract: Autocorrelation in animal movements can be both a serious
nuisance to analysis and a source of valuable information about the
scale and patterns of animal behavior, depending on the question and the
techniques employed. In this paper we present an approach to analyzing
the patterns of autocorrelation in animal movements that provides a
detailed picture of seasonal variability in the scale and patterns of
movement. We used a combination of moving window Mantel correlograms,
surface correlation and crosscorrelation analysis to investigate the
scales and patterns of autocorrelation in the movements of three herds
of elephants in northern Botswana. Patterns of autocorrelation of
elephant movements were long-range, temporally complicated, seasonally
variable, and closely linked with the onset of rainfall events.
Specifically, for the three elephant herds monitored there was often
significant autocorrelation among locations up to lags of 30 days or
more. During many seasonal periods there was no indication of decreasing
autocorrelation with increasing time between locations. Over the course
of the year, herds showed highly variable and complex patterns of
autocorrelation, ranging from random use of temporary home ranges,
periodic use of focal areas, and directional migration. Even though the
patterns of autocorrelation were variable in time and quite complex,
there were highly significant correlations among the autocorrelation
patterns of the different herds, indicating that they exhibited similar
patterns of movement through the year. These major patterns of
autocorrelation seem to be related to patterns of rainfall. The strength
of correlation in movement patterns of the different herds decreased
markedly at the cessation of major rain events. Also, there was a strong
crosscorrelation between strength of autocorrelation of movement and
rainfall, peaking at time lags of between three and four weeks. Overall,
these approaches provide a powerful way to explore the scales and
patterns of autocorrelation of animal movements, and to explicitly link
those patterns to temporally variable environmental attributes, such as
rainfall or vegetation phenology.
49.
Deem S.L., Brown J.L., Eggert L. et al. 2005.
Health and
management of working elephants in Myanmar (Burma). Procedings American
Association of Zoo Veterinarians, pp. 228-231.
Abstract: Myanmar has approximately 6,000 working elephants. Remaining
wild elephants are declining, partly because of live-capture for
captivity. Through health and reproductive assessments, genetic
analyses and GPS tracking of captive and wild elephants, we are
exploring linkages between the two populations and conducting studies to
reduce morbidity and mortality of captive elephants. Captive elephants
live and work in Myanmar's forests in close proximity and contact to the
remaining wild herds. We propose that reducing morbidity and mortality
in the captive elephants will decrease the need for live-capture, and
the risk of disease transmission, to wild elephants.
Introduction
There are an estimated 6,000 working elephants in Myanmar - half owned
by the government operated Myanmar Timber Enterprise (MTE) and half
owned privately.5 This may be one of the largest captive
elephant populations in the world and its management will have a
significant impact on remaining wild herds in Myanmar.4,6,8
With mortality rates higher than birth rates, the working population is
probably maintained by supplementing it with elephants captured from the
wild. 5 There is evidence that continued harvest of wild
elephants may have reduced the remaining wild populations of Myanmar.
Recent surveys of wild populations in two of Myanmar's protected
elephant ranges revealed extremely low dung counts, indicative of small
and declining herds. Constant contact with captive elephants in
Myanmar's forests may exacerbate the threat to Myanmar wild elephants by
increasing the transmission of disease between these two groups. For
both the above reasons, we believe that the conservation of wild
elephants in Myanmar will require significant improvements in the care
and management of currently existing captive populations.
Elephants owned by MTE receive veterinary care from the Burmese
veterinarians that work for the timber company and travel extensively
throughout the country to sites were the elephants are located.1
There is a dire need for veterinary supplies and laboratory capabilities
in the country. Currently, veterinary practices are based on the
extensive field experience of lead MTE veterinarians. However, MTE
veterinarians frequently rely on older published work 3,7 and
would benefit significantly from training that incorporates new insights
into elephant health and new veterinary techniques. Similarly, because
of their close-up experience of elephant health problems in the forests,
MTE veterinarians may be able to make important new contributions to the
care and management of elephants elsewhere.
The overall objective of our study is to work jointly with MTE
veterinarians to develop long-term captive population management
strategies to reduce mortality and increase births in the working timber
elephants and stop the continued off-take of animals from the wild to
supplement captive herds.
Methods
The health component of this study has five major objectives. These are
to:
1 Conduct a training workshop, in conjunction with MTE veterinarians,
on elephant management and veterinary care.
2 Develop protocols so that the MTE veterinarians can collect samples
for reproductive, genetic, and health status assessments.
3 Analyze samples and provide data to MTE veterinarians to improve
husbandry, preventive care and disease treatment of working elephants.
4 Develop a comprehensive bibliography of all published information on
the health and management of Myanmar elephants.
5 Perform an epidemiologic evaluation of records available on the
historic and current working elephant population.
Specific steps to achieve these objectives include:
1 Determine causes and rates of morbidity and mortality of captive MTE
elephants.
2 Determine causes of low rates of reproduction in captivity.
3 Develop a genetic profile of the captive herds.
4 Develop a protocol to assess oozies-Burmese mahout-expertise in
parallel with endocrine and health assessments to determine quality of
care and potentially related stress.
5 Develop small population viability models to assess how current
mortality effects long-term survival of the captive population and what
supplementation from the wild is needed for short- and long-term
sustainability.
6 Use population viability models to demonstrate how supplementation
from the wild will negatively affect that population.
7 Get baseline health parameter data on free-ranging elephants.
8 Quantify habitat/space use using GPS and satellite tracking of
captive and wild elephants.
Results and Discussion
During an initial exploratory visit in November 2004, we learned that
the annual mortality rate for MTE working elephants was 2.4% (66) in
2003. Deaths occurred in all age groups (>18 yr, n = 40; 4 - 17 yr, n =
11; <4 yr, n = 15) and included preventable diseases (i.e., poor
nutrition, heat stroke, diarrhea, dystocia, infectious and parasitic
agents). Additionally, we collected samples for performing health,
genetic and endocrine analyses of 22 elephants maintained in one of the
working camps (results to be presented). A relationship also was
established with the veterinary staff at the Yangon Zoo, including
follow up donations of veterinary literature and journals to the zoo. We
provided medical advice for the care of an orphaned elephant calf and
other animals housed at the zoo during our brief visit. We are seeking
funds for a training course to be conducted in late 2005 and hope to
perform health evaluations on a larger number of zoo and working
elephants during that visit.
The National Zoo already has an extensive conservation program for wild
elephants in Myanmar.4,6,8 This program has focused on
assessing wild elephant populations in protected areas and
satellite-tracking of four wild elephants to learn more about their
conservation status and ecology in Myanmar. Currently this work is
being extended to a national elephant survey. Part of this work included
collecting fecal samples for genetic and health assessments.
The Smithsonian team of researchers involved in this project
includes a veterinarian, reproduction physiologist, geneticist,
conservation biologist, and landscape ecologist. All members of this
multidisciplinary team have extensive experience working with elephants
and together provide the necessary expertise to study and understand the
numerous factors affecting Myanmar's captive elephants and the long-term
survival of elephants in Myanmar. These challenges range from human
land use and elephant population fragmentation, human-elephant conflict,
poor reproduction and health care of captive elephants and lack of
information on the health status of the wild elephants. A viable
conservation initiative for the elephants of Myanmar requires that
health issues be addressed as one component of a comprehensive program
to address the anthropogenic pressures on both working and wild
elephants.2
The elephants of Myanmar are an excellent example of the fine line
that exists between captive and wild animals, especially as it relates
to health. Captive and wild elephants are regularly in direct and
indirect contact. The working elephants live with their oozies who may
expose them to diseases, such as tuberculosis. The working elephants in
turn may encounter wild elephants at night in the forests where they
forage and live during non-working hours. In fact, the majority of
captive born calves are said to be sired by wild bulls. Potentially,
the use of working elephants in selectively extracting valuable timber
provides new strategies for the conservation of elephants and forests.
Most likely, "elephant-logging" is less damaging than machine-operated
timbering projects that tend to clear-cut areas and also damage the soil
and streams. However, decreasing the negative impact of such practices
(i.e., minimizing off-take of elephants from the wild, decreasing
disease risks to the wild elephants) is imperative.
LITERATURE CITED
1 Aung, T., and T. Nyunt. 2002. The care and management of the
domesticated Asian elephant in Myanmar. In: Baker, I., and M.
Kashio (eds.): Giants on our hands. Proc. Int. Workshop Domesticated
Asian Elephant. Dharmasarn Co., Ltd. Bangkok, Thailand. Pp. 89 - 102.
2 Deem, S.L., W.B. Karesh, and W. Weisman. 2001. Putting theory into
practice: wildlife health in conservation. Conserv. Biol. 5: 1224-1233.
3 Evans, G.H. 1910. Elephants and Their Diseases. Government Printing.
Rangoon. 323
4 Kelly, D.S. 2005. Habitat selection in declining elephant populations
of Alaungdaw Kathapa National Park. Masters Thesis. George Mason
University.
5 Lair, R.C. 1997. Myanmar. In: Gone Astray: The Care and
Management of the Asian Elephant in Domesticity. FAO Regional Office for
Asia and the Pacific, Thailand. RAP Publication. Pp. 99-131
6 Leimgruber, P., and C. Wemmer. 2004. National elephant symposium and
workshop. Report to the USFWS and the Myanmar Forest Department.
7 Pfaff, G. 1930. Reports on Diseases of Elephants. Government
Printing. Rangoon. 91
8 Wemmer, C., P. Leimgruber and D. S. Kelly. 2005. Managing wild
elephants in Alaungdaw Kathapa National Park and Htamanthi Wildlife
Sanctuary. Report to the USFWS and the Myanmar Forest Department.
50.
Ganswindt A., Heistermann M. and Hodges K. 2005. Physical,
physiological, and behavioral correlates of musth in captive African
elephants (Loxodonta africana).Physiological and Biochemical
Zoology 78: 505-514.
Abstract: Although musth in male African elephants (Loxodonta
africana) is known to be associated with increased aggressiveness,
urine dribbling (UD), temporal gland secretion (TGS), and elevated
androgens, the temporal relationship between these changes has not
been examined. Here, we describe the pattern of musth-related
characteristics in 14 captive elephant bulls by combining long-term
observations of physical and behavioral changes with physiological data
on testicular and adrenal function. The length of musth periods was
highly variable but according to our data set not related to age. Our
data also confirm that musth is associated with elevated androgens and,
in this respect, show that TGS and UD are downstream effects of this
elevation, with TGS responding earlier and to lower androgen levels than
UD. Because the majority of musth periods were associated with a
decrease in glucocorticoid levels, our data also indicate that musth
does not represent a physiological stress mediated by the
hypothalamic-pituitary-adrenal axis. Furthermore, we demonstrate that
the occurrence of musth is associated with increased aggression and that
this is presumably androgen mediated because aggressive males had higher
androgen levels. Collectively, the information generated contributes to
a better understanding of what characterizes and initiates musth in
captive African elephants and provides a basis for further studies
designed to examine in more detail the factors regulating the intensity
and duration of musth.
51.
Ganswindt A., Rasmssen H.B., Heistermann M. and Hodges J.K. 2005. The
sexually active states of free-ranging male African elephants (Loxodonta
africana): defining musth and non-musth using endocrinology, physical
signals, and behavior.Horm Behav 47: 83-91.
Abstract: Musth in male African elephants, Loxodonta africana, is
associated with increased aggressive behavior, continuous discharge of
urine, copious secretions from the swollen temporal glands, and elevated
androgen levels. During musth, bulls actively seek out and are preferred
by estrous females although sexual activity is not restricted to the
musth condition. The present study combines recently established methods
of fecal hormone analysis with long-term observations on male-female
associations as well as the presence and intensity of physical signals
to provide a more detailed picture about the physical, physiological,
and behavioral characteristics of different states of sexual activity in
free-ranging African elephants. Based on quantitative shifts in
individual bull association patterns, the presence of different physical
signals, and significant differences in androgen levels, a total of
three potential sub-categories for sexually active bulls could be
established. The results demonstrate that elevations in androgen levels
are only observed in sexually active animals showing temporal gland
secretion and/or urine dribbling, but are not related to the age of the
individual. Further, none of the sexually active states showed elevated
glucocorticoid output indicating that musth does not represent an HPA-mediated
stress condition. On the basis of these results, we suggest that the
term "musth" should be exclusively used for the competitive state in
sexually active male elephants and that the presence of urine dribbling
should be the physical signal used for defining this state.
52.
Garstang M. 2005. Long-distance, low-frequency elephant communication.J
Comp Physiol A Neuroethol Sens Neural Behav Physiol. 191: 299.
Abstract: Erratum: J Comp Physiol A Neuroethol Sens Neural Behav Physiol.
2004; Oct;190(10):791-805. Epub 2004 Sep 2. The production,
transmission, and reception of and the behavioral response to
long-distance, low-frequency sound by elephants is reviewed. The
structure of low-frequency calls generated by elephants is separated
into the "source" and the "filter" roles played by the lungs, larynx and
vocal track, the composition of the expired air and the ambient air
temperature. Implications regarding the size, age, sex, sexual and
physical status follow from the call structure and detection. Reception
of the signal is discussed in terms of the characteristics of the
elephant's ear with particular attention to the determination of the
threshold of hearing and the ability to locate the source of
low-frequency sounds. Factors which influence the transmission of near
infrasound are related to atmospheric structure. The critical role
played by the thermal stratification and vertical gradient and magnitude
of the wind in determining both the range and the detection of a signal
are discussed for open and closed elephant habitats. Infrasound plays a
pervasive role in reproduction, resource utilization, avoidance of
predation and other social interactions. Current and future technology
can be expected to contribute to the detection and interpretation of
elephant communication. This will aid in the understanding of behavior
and in efforts to sustain the species.
53.
Glickman S.E., Short R.V. and Renfree M.B. 2005. Sexual differentiation
in three unconventional mammals: Spotted hyenas, elephants and tammar
wallabies.Hormones and Behaviour 48: 403-417.
Abstract: The present review explores sexual differentiation in three
non-conventional species: the spotted hyena, the elephant and the tammar
wallaby, selected because of the natural challenges they present for
contemporary understanding of sexual differentiation. According to the
prevailing view of mammalian sexual differentiation, originally proposed
by Alfred Jost, secretion of androgen and anti-Mullerian hormone (AMH)
by the fetal testes during critical stages of development accounts for
the full range of sexually dimorphic urogenital traits observed at
birth. Jost's concept was subsequently expanded to encompass sexual
differentiation of the brain and behavior. Although the central focus of
this review involves urogenital development, we assume that the novel
mechanisms described in this article have potentially significant
implications for sexual differentiation of brain and behavior, a
transposition with precedent in the history of this field. Contrary to
the ''specific'' requirements of Jost's formulation, female spotted
hyenas and elephants initially develop male-type external genitalia
prior to gonadal differentiation. In addition, the administration of
anti-androgens to pregnant female spotted hyenas does not prevent the
formation of a scrotum, pseudoscrotum, penis or penile clitoris in the
offspring of treated females, although it is not yet clear whether the
creation of masculine genitalia involves other steroids or whether there
is a genetic mechanism bypassing a hormonal mediator. Wallabies, where
sexual differentiation occurs in the pouch after birth, provide the most
conclusive evidence for direct genetic control of sexual dimorphism,
with the scrotum developing only in males and the pouch and mammary
glands only in females, before differentiation of the gonads. The
development of the pouch and mammary gland in females and the scrotum in
males is controlled by genes on the X chromosome. In keeping with the
''expanded'' version of Jost's formulation, secretion of androgens by
the fetal testes provides the best current account of a broad array of
sex differences in reproductive morphology and endocrinology of the
spotted hyena, and androgens are essential for development of the
prostate and penis of the wallaby. But the essential circulating
androgen in the male wallaby is 5α androstanediol, locally converted in
target tissues to DHT, while in the pregnant female hyena,
androstenedione, secreted by the maternal ovary, is converted by the
placenta to testosterone (and estradiol) and transferred to the
developing fetus. Testicular testosterone certainly seems to be
responsible for the behavioral phenomenon of musth in male elephants.
Both spotted hyenas and elephants display matrilineal social
organization, and, in both species, female genital morphology requires
feminine cooperation for successful copulation. We conclude that not all
aspects of sexual differentiation have been delegated to testicular
hormones in these mammals. In addition, we suggest that research on
urogenital development in these non-traditional species directs
attention to processes that may well be operating during the sexual
differentiation of morphology and behavior in more common laboratory
mammals, albeit in less dramatic fashion.
54.
Leong K.M., Burks K., Rizkalla C.E. and Savage A. 2005. Effects of
reproductive and social context on vocal communication in captive female
African elephants (Loxodonta africana).Zoo Biology 24: 331-347.
Abstract: Female African elephants advertise changes in reproductive
condition to males through a variety of modalities, including an
increase in low-frequency vocalizations, presumed to travel long
distances. Although males respond to these vocalizations, it has been
suggested that their proximate function may be to signal to nearby
females rather than to distant males. Because elephants live in a
female-bonded society, it is likely that changes in female
reproductive condition also affect close-range interactions between
high- and low-ranking females and that vocalizations may mediate these
interactions. To examine female-female interactions related to vocal
production and the ovulatory cycle, this year-long study monitored
behavior, vocalizations and hormonal cycles for a group of six female
captive African elephants at Disney's Animal Kingdom. Rates of several
types of close-range interactions were observed to change over the
phases of the estrous cycle, and rank seemed to affect whether or not
low-frequency vocalizations were given in association with these
interactions. Results of this study suggest that a female African
elephant's immediate social context and rank in the social hierarchy
interact with the hormonal cycle in the production of low-frequency
vocalizations, thus many of these vocalizations may not function
proximately as signals to distant males, but may be a result of the
changing dynamics among females.
55.
Nissani M., Hoefler-Nissani D., Lay U.T. and Htun U.W. 2005.
Simultaneous visual discrimination in Asian elephants.J Exp Anal Behav
83: 15-29.
Abstract: Two experiments explored the behavior of 20 Asian elephants
(Elephas aximus) in simultaneous visual discrimination tasks. In
Experiment 1, 7 Burmese logging elephants acquired a white+/black-
discrimination, reaching criterion in a mean of 2.6 sessions and 117
discrete trials, whereas 4 elephants acquired a black+/white-
discrimination in 5.3 sessions and 293 trials. One elephant failed to
reach criterion in the white+/black- task in 9 sessions and 549 trials,
and 2 elephants failed to reach criterion in the black+/white- task in 9
sessions and 452 trials. In Experiment 2, 3 elephants learned a
large/small transposition problem, reaching criterion within a mean of
1.7 sessions and 58 trials. Four elephants failed to reach criterion in
4.8 sessions and 193 trials. Data from both the black/white and
large/small discriminations showed a surprising age effect, suggesting
that elephants beyond the age of 20 to 30 years either may be unable to
acquire these visual discriminations or may require an inordinate number
of trials to do so. Overall, our results cannot be readily reconciled
with the widespread view that elephants possess exceptional
intelligence. Department of Interdisciplinary Studies, Wayne State
University, Detroit, Michigan 48202, USA. Moti.Nissani@wayne.edu
56.
Ortolani A., Leong K., Graham L. and Savage A. 2005. Behavioral indices
of estrus in a group of captive African elephants (Loxodonta africana).Zoo
Biology 24: 311-329.
Abstract: This study investigated behavioral signals of estrus by
systematically monitoring the interactions of one male with four female
African elephants housed in a naturalistic outdoor enclosure at Disney's
Animal Kingdom over a period of 11 months. We measured changes in five
spatial behaviors and 22 tactile-contact behaviors, as well as changes
in serum progestagen and LH concentrations, across three ovarian cycles
for each female. Two females did not cycle during the study. Three
different phases of the ovarian cycle were identified: mid luteal,
anovulatory follicular, ovulatory follicular. The male followed more
and carried out more genital inspections, flehmen, and trunk-to-mouth
behaviors toward cycling females during their ovulatory phase. Genital
inspections by the male peaked above baseline levels on the day of an
LH surge, and up to 9 days before, in both cycling females and, thus,
might be a useful behavioral index of estrus. The male also carried out
more genital inspections, flehmen, and trunk touches to the back leg
toward ovulatory cycling than noncycling females. Overall, our results
indicated that: 1) a single subadult African elephant male could
discriminate two females in the ovulatory phase of their cycle (i.e.,
during the 3 weeks preceding ovulation) from the mid luteal phase; 2)
the male also discriminated two cycling females in the ovulatory and
anovulatory follicular phases from two noncycling females; 3) two
females in the ovulatory phase of the cycle displayed a greater variety
of tactile-contact behavior toward the male compared to the other
cycle phases.
57.
Perez-Barberia F.J. and Gordon I.J. 2005. Gregariousness increases brain
size in ungulates.Oecologia 145: 41-52.
Abstract: The brain's main function is to organise the physiological and
behavioural responses to environmental and social challenges in order to
keep the organism alive. Here, we studied the effects that
gregariousness (as a measurement of sociality), dietary habits,
gestation length and sex have on brain size of extant ungulates. The
analysis controlled for the effects of phylogeny and for random
variability implicit in the data set. We tested the following groups of
hypotheses: (1) Social brain hypothesis-gregarious species are more
likely to have larger brains than non-gregarious species because the
former are subjected to demanding and complex social interactions; (2)
Ecological hypothesis-dietary habits impose challenging cognitive tasks
associated with finding and manipulating food (foraging strategy); (3)
Developmental hypotheses (a) energy strategy: selection for larger
brains operates, primarily, on maternal metabolic turnover (i.e.
gestation length) in relation to food qu |
