American alligator (Alligator mississippiensis) weight gain in captivity and implications for captive reptile body condition

The body condition of an animal is an indicator of health status and is dependent upon many factors, some of which can vary between wild and captive settings. Despite this, there have not been many studies on how captivity affects body condition relative to wild animal populations. This study explores the body condition of captive and wild American alligators (Alligator mississippiensis) because reptiles are frequently overlooked in studies of captive animal health and because alligators are well-represented in captivity. We collected body condition data from 209 captive alligators and 935 wild alligators throughout Florida and southeastern Georgia and compared the relationships between body condition and body length for each group. We found that captive alligators exhibited significantly higher body condition values as they aged, and that this result was driven by the difference between captive and wild males. Body condition values for captive juveniles did not differ from wild juveniles, but they differed when comparing adults. Our results suggest that factors such as diet and movement rates play major roles in determining alligator body condition and that body condition may be an important metric for monitoring captive alligator health, especially for older adult males.     

Dominance and reproductive rates in captive female olive baboons, Papio anubis

The reproductive cycles of 23 captive olive baboons were studied over two successive parturitions. Interbirth intervals of 450 days were reduced by 60% in comparison to wild baboons, and consisted of 145 days of postpartum amenorrhea, 3.5 cycles, and a gestation of 185 days. Dominance rank was found to be one significant factor affecting female fertility. Low-ranking females had longer total intervals between successive births and, in particular, they experienced a longer delay to conception once they had resumed sexual cycles. Mothers of infants who were heavy for age resumed cycling more quickly and had fewer cycles before a subsequent conception. Mothers best able to sustain rapid early infant growth were those of high dominance rank and of high body mass; these females had more rapid reproductive rates. As female energy intake was unrelated to dominance, we suggest that social stresses are important suppressors of the hormonal and lactational competence of subordinate females.     

Teeth emergence in wild olive baboons in Kenya and formulation of a dental schedule for aging wild baboon populations

Teeth emergence schedules are presented from analysis of 95 wild olive baboons Papio anubis (age range 2–120 months) and compared to recently published results for wild and captive yellow baboons (P. cynocephalus; Phillips-Conroy and Jolly: American Journal of Primatology 15:17–29, 1988). Age at emergence of M1 (20.5 months males, 19.5 months females), I1 (32.5 and 33.5 months) and I2 (40.0 and 39 months) of olive baboons was earlier than in the wild yellow baboons and similar to captive yellow baboons. However, the later emerging teeth were delayed considerably relative to the captive animals and were similar in age of emergence to those of wild yellow baboons. Considerable variation in age of emergence occurred in the later emerging teeth especially among males. Regression analysis of dental scores with age demonstrated differences between olive baboons and captive yellow baboons but not between olive baboons and wild yellow baboons. Combined data on dental scores for wild yellow, olive, and hamadryas baboons provide schedules of AGE (months) = {SCORE – 11.79} ÷ 0.4405 and AGE (months) = {SCORE – 11.24} ÷ 0.4797 for males and females, respectively, which may be used for aging wild baboons. Full permanent dentition in wild baboons is predicted to occur over 1 year later than in captive animals.     

Kinetics of stable isotope and body composition in olive baboons (Papio anubis) estimated by deuterium dilution space: a pilot study

Morphometrics and isotope-labelled water were used to determine body composition [total body water, total body fat and fat-free mass (FFM)] of three captive female olive baboons (Papio anubis). Mean mass was 16.5 kg, comparable with other captive settings but heavier than wild olive baboons. Average water content was 66%; FFM averaged 90.5%. Baboon females have less body fat than human counterparts. Compared with captive or wild baboons, these females were adequately nourished for their energy expenditure. A positive association between total mass and FFM existed, but due to the small sample no general relationship was observed for body fat or FFM and condition or size measures. The kinetics of deuterium equilibration in body fluids for baboons was determined as 3-4 hours after injection, similar to that for humans. Deuterium dilution technique appears to be an appropriate method for studying body composition in baboons, although a larger sample is needed for relationships between morphometric indices and body composition.     

Agonistic Interactions of Juvenile Savanna Baboons

19 juvenile members of known genealogies in two wild baboon groups were studied over a 16-month period to compare the ontogeny of agonistic experience and dominance relations for males and females. Juveniles of all age-sex classes were disproportionately likely to receive aggression from and submit to adult males per unit of time spent in proximity. This pattern intensified with increasing juvenile age. With age, juvenile females more often submitted to unrelated adult females from higher-ranking families, whereas this was not true for juvenile males. All juveniles received aggression from older group members more often during feeding than was expected by chance. High rates of agonistic interaction with unrelated adult females accounted for old juvenile females (3–5.5 years-old) interacting agonistically more frequently than male age peers and young juveniles of either sex (1–2.5 years-old). Adult females were also more aggressive toward females among young juveniles, suggesting that adult females target females among juveniles for aggression and resistance to rank reversal. Within juvenile age groups, males dominated all females and all younger males, irrespective of maternal dominance status. Dominance relations among female age-peers were generally isomorphic with relations among their mothers. No juvenile targeted any older male for rank reversal. Males targeted all older females, whereas females typically targeted only older females from families lower-ranking than their own. The strong sexual dimorphism in adult body size in baboons may explain why juvenile males' dominance relations with peers and adult females are not structured along lines of family membership as is true for the less dimorphic macaques. Acquisition of higher agonistic status probably allows juveniles of both sexes to increase their success in within-group feeding competition during late stages of juvenility, which, in turn, could affect important life-history traits such as age at menarche and adult body size.     

Life history and the competitive environment: trajectories of growth,maturation, and reproductive output among chacma baboons

The social environment is a key feature influencing primate life histories. Chacma baboons (Papio hamadryas ursinus) are a female-bonded species with a strict linear dominance hierarchy. In this species, the allocation of energy to competing demands of growth and reproduction is hypothesized to vary as a function of competitive ability, which in turn increases with social rank. Since growth rate is a major component of life history models, measures of age-specific growth were used to analyze variation in life history traits across social ranks. Weights of 42 immature baboons were obtained without sedation or baiting from a troop of well-habituated chacma baboons in the Okavango Delta, Botswana. Using demographic and weight data from this wild population, five main findings emerged: 1) Weight for age and growth rate of infant and juvenile females are positively associated with maternal rank. 2) Male growth is not influenced by maternal rank. 3) Female growth shows smaller variation across feeding conditions than male growth. 4) Low-ranking adult females continue investment in offspring through prolonged lactation until they reach a weight comparable to that of high-ranking infants. 5) The benefit of rank to reproductive success shown in this study is 0.83 additional offspring. Reproductive span determined predominantly by age at maturation contributes 27-38% to the difference in expected number of offspring by rank, vs. 62-73% due to reproductive rate. These findings have major implications for understanding the role of social environment in phenotypic plasticity of life history traits, and in the evolution of primate life histories.     

Body mass and growth rates in captive chimpanzees (Pan troglodytes) cared for in African wildlife sanctuaries,zoological institutions,and research facilities

Captive chimpanzees (Pan troglodytes) mature earlier in body mass and have a greater growth rate compared to wild individuals. However, relatively little is known about how growth parameters compare between chimpanzees living in different captive environments. To investigate, body mass was measured in 298 African sanctuary chimpanzees and was acquired from 1030 zoological and 442 research chimpanzees, using data repositories. An analysis of covariance, adjusting for age, was performed to assess same-sex body mass differences between adult sanctuary, zoological, and research populations. Piecewise linear regression was performed to estimate sex-specific growth rates and the age at maturation, which were compared between sexes and across populations using extra-sum-of-squares F tests. Adult body mass was greater in the zoological and resarch populations compared to the sanctuary chimpanzees, in both sexes. Male and female sanctuary chimpanzees were estimated to have a slower rate of growth compared with their zoological and research counterparts. Additionally, male sanctuary chimpanzees were estimated to have an older age at maturation for body mass compared with zoological and research males, whereas the age at maturation was similar across female populations. For both the zoological and research populations, the estimated growth rate was greater in males compared to females. Together, these data contribute to current understanding of growth and maturation in this species and suggest marked differences between the growth patterns of chimpanzees living in different captive environments.     

Cross-sectional growth standards for captive baboons: II. Organ weight by body weight

We present the first cross-sectional organ weight by body weight reference standards for captive baboons (Papio hamadryas). Organ weight data were obtained from necropsy reports for 634 healthy, pedigreed, captive female and male baboons. From summary statistics we calculated and fit cross-sectional sex-specific percentile curves for: adrenals, brain, eyes, heart, kidneys, liver plus gall bladder, lungs, pancreas, pituitary gland, spleen, and thyroid gland in three kilogram body weight intervals and cross-sectional summary statistics by sex for each organ in one kilogram body weight intervals.     

Testicular Size,Mating System,and Maturation Schedules in Wild Anubis and Hamadryas Baboons

We report body mass and testicular size in 258 anubis (Papio anubis or P. hamadryas anubis) and 59 hamadryas (P. hamadryas or P. h. hamadryas) baboons, live-trapped in Ethiopia. As predicted by theories of sexual selection by sperm competition, among hamadryas baboons, which are monandrous, fully adult males have absolutely and relatively smaller testes than those of comparable males among anubis baboons, which are polyandrous. Male hamadryas are also ca. 10% smaller in bodily mass as adults. The intertaxonal difference in adults is due entirely to the fact that in male anubis baboons, testicular and bodily mass continue to grow up to full adulthood–the age at which most males emigrate from their natal troop and initiate a confrontational breeding strategy among unrelated animals. By contrast, male hamadryas baboons, which are usually philopatric, attain adult body mass and testicular size as subadults. In both species, juveniles experience rapid testicular growth peaking in rate at ca. 12kg body mass, but testicular descent and growth starts earlier in hamadryas than in anubis baboons. Juvenile hamadryas baboons have relatively larger testes than their anubis equivalents, perhaps because male philopatry allows the mating strategy of male hamadryas baboons to be initiated during juvenile life and therefore permits some sperm competition between juveniles and adults.     

Canine Length in Wild Male Baboons: Maturation,Aging and Social Dominance Rank

Canines represent an essential component of the dentition for any heterodont mammal. In primates, like many other mammals, canines are frequently used as weapons. Hence, tooth size and wear may have significant implications for fighting ability, and consequently for social dominance rank, reproductive success, and fitness. We evaluated sources of variance in canine growth and length in a well-studied wild primate population because of the potential importance of canines for male reproductive success in many primates. Specifically, we measured maxillary canine length in 80 wild male baboons (aged 5.04–20.45 years) from the Amboseli ecosystem in southern Kenya, and examined its relationship with maturation, age, and social dominance rank. In our analysis of maturation, we compared food-enhanced baboons (those that fed part time at a refuse pit associated with a tourist lodge) with wild-feeding males, and found that food-enhanced males achieved long canines earlier than wild-feeding males. Among adult males, canine length decreased with age because of tooth wear. We found some evidence that, after controlling for age, longer canines were associated with higher adult dominance rank (accounting for 9% of the variance in rank), but only among relatively high-ranking males. This result supports the idea that social rank, and thus reproductive success and fitness, may depend in part on fighting ability mediated by canine size.     

Cross-sectional growth standards for captive baboons: I. Organ weight by chronological age

We present the first cross-sectional organ weight reference standards for captive baboons (Papio hamadryas). Organ weight data were obtained from necropsy reports for 634 healthy, pedigreed, captive female and male baboons. From summary statistics we calculated and fit cross-sectional, sex-specific percentile curves for: adrenals, brain, eyes, heart, kidneys, liver plus gall bladder, lungs, pancreas, pituitary gland, spleen, and thyroid gland in two year age class intervals and summary statistics by sex for each organ in one year age classes.     

The endocrinology of pregnancy and fetal loss in wild baboons

An impressive body of research has focused on the mechanisms by which the steroid estrogens (E), progestins (P), and glucocorticoids (GC) ensure successful pregnancy. With the advance of non-invasive techniques to measure steroids in urine and feces, steroid hormones are routinely monitored to detect pregnancy in wild mammalian species, but hormone data on fetal loss have been sparse. Here, we examine fecal steroid hormones from five groups of wild yellow baboons (Papio cynocephalus) in the Amboseli basin of Kenya to compare the hormones of successful pregnancies to those ending in fetal loss or stillbirth. Using a combination of longitudinal and cross-sectional data, we analyzed three steroid hormones (E, P, GC) and related metabolites from 5 years of fecal samples across 188 pregnancies. Our results document the course of steroid hormone concentrations across successful baboon pregnancy in the wild and demonstrate that fecal estrogens predicted impending fetal loss starting 2 months before the externally observed loss. By also considering an additional 450 pregnancies for which we did not have hormonal data, we determined that the probability for fetal loss for Amboseli baboons was 13.9%, and that fetal mortality occurred throughout gestation (91 losses occurred in 656 pregnancies; rates were the same for pregnancies with and without hormonal data). These results demonstrate that our longstanding method for early detection of pregnancies based on observation of external indicators closely matches hormonal identification of pregnancy in wild baboons.     

Mortality and the magnitude of the "wild effect" in chimpanzee tooth emergence

Age of tooth emergence is a useful measure of the pace of life for primate species, both living and extinct. A recent study combining wild chimpanzees of the Taï Forest, Gombe, and Bossou by Zihlman et al. (2004) suggested that wild chimpanzees erupt teeth much later than captives, bringing into question both comparisons within the hominin fossil record and assessment of chimpanzees. Here, we assess the magnitude of the “wild effect” (the mean difference between captive and wild samples expressed in standard deviation units) in these chimpanzees. Tooth emergence in these wild individuals is late, although at a more moderate level than previously recorded, with a mean delay conservatively estimated at about 1 SD compared to the captive distributions. The effect rises to 1.3 SD if we relax criteria for age estimates. We estimate that the mandibular M1 of these wild chimpanzees emerges at about 3 ²/₃-3 ¾ years of age. An important point, often ignored, is that these chimpanzees are largely dead of natural causes, merging the effect of living wild with the effect of early death. Evidence of mortality selection includes, specifically: younger deaths appear to have been more delayed than the older in tooth emergence, more often showed evidence of disease or debilitation, and revealed a higher occurrence of dental anomalies. Notably, delay in tooth emergence for live-captured wild baboons appears lower in magnitude (ca. 0.5 SD) and differs in pattern. Definitive ages of tooth emergence times in living wild chimpanzees must be established from the study of living animals. The fossil record, of course, consists of many dead juveniles; the present study has implications for how we evaluate them.     

Body Weight of Wild and Captive Common Marmosets (Callithrix jacchus)

Captive studies and occasional trappings of wild individuals indicate that callitrichids have small size and body weight and lack sexual dimorphism. We compared body weights of captive and wild Callithrix jacchus obtained by repeatedly weighing subjects from two populations in Brazil. We obtained captive data by routinely weighing 138 individuals from the Universidade Federal do Rio Grande do Norte colony and wild data via regular trapping of 243 individuals in 15 free-ranging groups from IBAMA's field site in Nísia Floresta. We assigned all subjects to one of four age classes—infant, juvenile, subadult, and adult—according to their birth dates or size, reproductive status, and dental development. There is no significant difference between males and females in any of the four age classes, but captive subjects were heavier than wild ones in all age classes but infant. Reproductive and nonreproductive adult females showed no statistical difference in weight. These results accord with previous reports of lack of body size sexual dimorphism in common marmosets and suggest that differences between wild and captive common marmosets are not constitutional, but are instead a consequence of diet and physical activity. The absence of weight difference between reproductive and nonreproductive females suggests that any possible advantage from high rank is outweighed by the costs of reproduction in common marmosets.     

Growth in colony living anubis baboon infants and its relationship with maternal activity budgets and reproductive status

Early growth is of interest because it is susceptible to maternal effects and linked to fitness components for a range of species. Here we present anthropometric measurements on 23 infant olive baboons born into a captive colony in order to describe growth over the first 2 years of life, to explore maternal influences on growth, and to assess the impact of growth profiles on maternal reproduction. Six main findings emerged: 1) Infant growth rates in our colony were higher than those reported for wild populations but comparable to those observed for food-enhanced animals. 2) The ratio of infant mass to maternal mass was positively associated with reproductive parameters, such as duration of post-partum amenorrhea and interbirth interval. 3) Mothers resumed cycling and reconceived when their infants attained a relatively consistent threshold mass. 4) Infant mass-for-age was associated with maternal rank and, independently, with maternal mass such that females of high dominance rank and heavy females had relatively large infants at their resumption of cycling. 5) Low-ranking and lighter females had longer investment periods but smaller infants. They continued investment in infant through prolonged lactation until their infants reached a mass similar to that of infants of high-ranking/heavy mothers, suggesting that the lengthening of investment is essentially compensatory for slow early growth. 6) There was no relationship between infant growth and maternal activity budgets. Maternal physical and social factors, not energetics, contributed to differences among infants in growth trajectories, and infant growth temporally influenced successive reproductive events.     

Dental eruption schedules of wild and captive baboons

Dental eruption schedules previously used to age wild baboons have in the past derived from studies of captive animals housed under standard conditions and fed standard laboratory diets. This paper reports for the first time eruption schedules derived from wild baboons, the yellow baboons (Papio hamadryas cynocephalus) of Mikumi National Park, Tanzania, and compares these schedules with those of other baboon subspecies inhabiting both similar and dissimilar environments. Eighteen males and twelve females from the Viramba groups, ranging in age from 21 to 103 months, were trapped, and dental impressions and notes were made of the state of eruption of each tooth. Eruption of all teeth were delayed at Mikumi relative to the baboon standards derived from the captive animals at the Southwest Foundation for Biomedical Research, San Antonio, Texas. Teeth of the canine-premolar 3 complex and third molars were most delayed, erupting up to a year and a half later than their counterparts from captive animals. Comparison with data on hamadryas baboons from Erer-Gota in Ethiopia revealed that both the hamadryas and yellow subspecies of baboons, with different genetic backgrounds and living under markedly different environmental conditions, followed the same schedule. This constancy of developmental schedules suggests that these Mikumi data may reasonably be used as standards for other wild baboon populations and that acceleration of dental maturation, as well us maturation of other somatic systems in captivity, is another manifestation of the short-term adaptive plasticity of the baboon species as a whole.     

Reproductive maturation in a sample of captive male baboons

Though baboons have been considered an appropriate non-human primate model for studying human reproductive and endocrine development. the overall similarity of reproductive maturation between the two species is unclear. This paper examines the role of testicular and adrenal hormones for pubertal changes in a cross-sectional sample of 21 captive male savanna baboons. Morphometric and hormonal indices demonstrate changes in size and gonadal function, but not adrenal function, during pubertal maturation among baboons. Results also indicate that gonadal, but not adrenal, androgens are related to morphometric variables. We conclude that savanna baboons do not make an appropriate evolutionary model of human pubertal maturation.     

Ontogenetic Scaling of Fore- and Hind Limb Posture in Wild Chacma Baboons (Papio hamadryas ursinus)

Large-scale interspecific studies of mammals ranging between 0.04–280 kg have shown that larger animals walk with more extended limb joints. Within a taxon or clade, however, the relationship between body size and joint posture is less straightforward. Factors that may affect the lack of congruence between broad and narrow phylogenetic analyses of limb kinematics include limited sampling of (1) ranges of body size, and/or (2) numbers of individuals. Unfortunately, both issues are inherent in laboratory-based or zoo locomotion research. In this study, we examined the relationship between body mass and elbow and knee joint angles (our proxies of fore- and hind limb posture, respectively) in a cross-sectional ontogenetic sample of wild chacma baboons (Papio hamadryas ursinus) habituated in the De Hoop Nature Reserve, South Africa. Videos were obtained from 33 individuals of known age (12 to ≥108 months) and body mass (2–29.5 kg) during walking trials. Results show that older, heavier baboons walk with significantly more extended knee joints but not elbow joints. This pattern is consistent when examining only males, but not within the female sample. Heavier, older baboons also display significantly less variation in their hind limb posture compared to lighter, young animals. Thus, within this ontogenetic sample of a single primate species spanning an order of magnitude in body mass, hind limb posture exhibited a postural scaling phenomenon while the forelimbs did not. These findings may further help explain 1) why younger mammals (including baboons) tend to have relatively stronger bones than adults, and 2) why humeri appear relatively weaker than femora (in at least baboons). Finally, this study demonstrates how field-acquired kinematics can help answer fundamental biomechanical questions usually addressed only in animal gait laboratories.     

Trade-offs in skillacquisition and time allocation among juvenile chacma baboons

We hypothesize that juvenile baboons are less efficient foragers than adult baboons owing to their small size, lower level of knowledge and skill, and/or lesser ability to maintain access to resources. We predict that as resources are more difficult to extract, juvenile baboons will demonstrate lower efficiency than adults will because of their lower levels of experience. In addition, we hypothesize that juvenile baboons will be more likely to allocate foraging time to easier-to-extract resources owing to their greater efficiency in acquiring those resources. We use feeding efficiency and time allocation data collected on a wild, free-ranging, non-provisioned population of chacma baboons (Papio hamadryas ursinus) in the Moremi Wildlife Reserve, Okavango Delta, Botswana to test these hypotheses. The major findings of this study are: 1. Juvenile baboons are significantly less efficient foragers than adult baboons primarily for difficult-to-extract resources. We propose that this age-dependent variation in efficiency is due to differences in memory and other cognitive functions related to locating food resources, as is indicated by the greater amount of time juvenile baboons spend searching for food. There is no evidence that smaller body size or competitive disruption influences the differences in return rates found between adult and juvenile baboons in this study. 2. An individual baboon’s feeding efficiency for a given resource can be used to predict the duration of its foraging bouts for that resource. These results contribute both to our understanding of the ontogeny of behavioral development in nonhuman primates, especially regarding foraging ability, and to current debate within the field of human behavioral ecology regarding the evolution of the juvenile period in primates and humans. Sara E. Johnson is Assistant Professor of Anthropology at California State University, Fullerton. She received her Ph.D. in Anthropology (Human Evolutionary Ecology) from the University of New Mexico in 2001. She uses behavioral ecology and life history theory to address her research interests in the evolution of primate and human growth; ecological variation and phenotypic plasticity in growth and development; ecological variation in life course trajectories, including fertility, health, morbidity, and mortality differentials; food acquisition and production related to nutrition; societal transofmration and roles of the elderly among indigenous peoples; and women’s reproductive and productive roles in both traditional and nontraditional societies. For the past decade she has conducted research on these issues in several different populations, including chacma baboons in the Okavango Delta of Botswana, two multiethnic communities of forager/agropastoralists in the Okavango Delta of Botswana, and among New Mexican men. John Bock is Associate Professor of Anthropology at California State University at Fullerton and is Associate Editor of Human Nature. He received a Ph.D. in Anthropology (Human Evolutionary EcologY) from the University of New Mexico in 1995, and from 1995 to 1998 was an Andrew W. Mellon Foundation postdoctoral fellow in demography and epidemiology at the National Centre for Epidemiology and Population Health at Australian National University. His recent research has focused on applying life history theory to understanding the evolution of the primate and human juvenile period. Bock has been conducting research among the Okavango Delta peoples of Botswana since 1992, and his current research there is an examination of child development and family demography in relation to socioecology and the HIV/AIDS epidemic. Other research is focused on health disparties among minorities and indigenous peoples in Botswana and the United States related to differential access to health care.