Ontogeny of locomotion in mouse lemurs: Implications for primate evolution.

The environment of juvenile primates is very challenging. They have to forage and move on the same substrates as adults do and escape the same predators, despite their immature state. In this study, we explore the developmental strategies that may provide effective locomotor abilities early in life. This could provide new insights into the selective pressures acting on juvenile primates and into evolution of primate locomotion. We conducted an ontogenetic study of 36 arboreal gray mouse lemurs from birth to adulthood (6 months of age). The investigated parameters were, for both limbs, (1) grasping behavior during locomotion (i.e., grip postures), (2) grasping performance (i.e., pull strength), and (3) motor coordination (i.e., rotarod test). Our results show that 8-day-old babies are able to climb substrates of various slopes and diameters outside of their nest. Although juveniles cannot successfully complete a motor coordination test before 30 days of age, young individuals display relative pull strengths that are very high or even on par with adults, guaranteeing stability on narrow substrates. These powerful grasps highlight the importance of the grasping function for these juveniles that are not carried and move independently on arboreal substrates shortly after their first week of life. Moreover, the pedal grasping provides a secure grasp on all substrates across ontogeny; however, manual secure grasps decrease during development, being highly used only shortly after birth on vertical and narrow substrates. These results first suggest different functional roles of the hands and feet, with the hind limbs ensuring body balance on the substrates, freeing the upper limbs for manipulation. They further show vertical and narrow branches to be especially challenging, requiring strong grasps, which suggests that they may drive the evolution of strong grasping abilities in primates.

The development of socio-sexual behavior in belugas (Delphinapterus leucas) under human care.

Although a catalog of beluga socio-sexual behavior has been established, to date, little is known about the development of beluga (Delphinapterus leucas) socio-sexual behavior. The present study explored how socio-sexual behavior developed in belugas under human care by recording the behavior of 5 belugas between years 4 and 10 of life. Overall, the presence of young male conspecifics was the most influential predictor of whether or not the subjects engaged in socio-sexual behavior, and social networks particularly emphasized the relationships between males in the social group. The subjects of the present study were also more likely to be involved in socio-sexual behavior as they matured and were more likely to be involved if they were male. Additionally, specific socio-sexual behaviors of the repertoire, including horizontal s-postures and pelvic thrusts, increased in prevalence throughout development. These findings have implications for conservation efforts as social group composition may contribute to the development of socio-sexual behavior, which in turn may influence the reproductive success of beluga populations. Furthermore, because socio-sexual behavior composes a substantial portion of a beluga's activity budget and the majority of the time spent socializing, it is likely crucial for social bonding and well-being in belugas, especially males.

Modeling variation in the growth of wild and captive juvenile vervet monkeys in relation to diet and resource availability.

OBJECTIVES: To compare longitudinal weight gain in captive and wild juvenile vervet monkeys and conduct an empirical assessment of different mechanistic growth models. METHODS: Weights were collected from two groups of captive monkeys and two consecutive cohorts of wild monkeys until the end of the juvenile period (~800 days). The captive groups were each fed different diets, while the wild groups experienced different ecological conditions. Three different growth curve models were compared. RESULTS: By 800 days, the wild juveniles were lighter, with a slower maximum growth rate, and reached asymptote earlier than their captive counterparts. There were overall differences in weight and growth rate across the two wild cohorts. This corresponded to differences in resource availability. There was considerable overlap in growth rate and predicted adult weight of male and females in the first, but not the second, wild cohort. Maternal parity was not influential. While the von Bertalanffy curve provided the best fit to the data sets modeled together, the Logistic curve best described growth in the wild cohorts when considered separately. CONCLUSIONS: The growth curves of the two captive cohorts are likely to lie near the maximum attainable by juvenile vervets. It may be helpful to include deviations from these rates when assessing the performance of wild vervet monkeys. The comparison of wild and captive juveniles confirmed the value of comparing different growth curve models, and an appreciation that the best models may well differ for different populations. Choice of mechanistic growth model can, therefore, be empirically justified, rather than theoretically predetermined.

Weigh and see-Body mass recordings versus body condition scoring in European zoo elephants (Loxodonta africana and Elephas maximus).

Regular body mass (BM) monitoring plays a key role in preventative health care of zoo animals. In some species, including African (Loxodonta africana) and Asian elephants (Elephas maximus), the process of weighing can be challenging, and alternative methods such as visual body condition scoring (BCS) have been developed. We investigated the temporal development of both parameters regarding correlation patterns between them, and their suitability as monitoring measures in dependence of an elephant's life stage. While BM is more suitable in calves and juveniles under the age of 8 years, both BM and BCS are considered equally reliable in adult elephants. In elephants over the age of 40 years, BCS might be more suitable for assessing the physical status. Independent of species and sex, juvenile zoo elephants grow in BM nearly linearly with age, and reach a higher BM at an earlier age compared with conspecifics of free-ranging and semi-captive populations in the countries of origin. The BCS typically remains constant during this life stage, seemingly unaffected by growth. In adult animals, breeding females have a lower BM and BCS than nonbreeders, and BM and BCS typically indicate fluctuations in the same direction. In geriatric elephants (>40 years) a drop in BCS occurs commonly, while BM may even increase in this life stage. We recommend regular body mass recording in zoo elephants to enhance our knowledge of body mass development and allow the formulation of objective practical recommendations. BCS presents a valuable and simple tool for complementary monitoring of an elephant's condition, especially in adult and geriatric individuals.

Accidentally catching of the catfish Lophiosilurus alexandri (Steindachner, 1876) larvae in aquariums with different colors / Interferência de cores de aquários nas larvas do bagre Lophiosilurus alexandri (Steindachner, 1876) e seu tratador

Abstract The aim of this study was to evaluate the effect of different colors in development and survival of catfish Lophiosilurus alexandri larvae, as well as over the visual ability of the handler. Larvae were placed in 5 L-aquariums at a density of 7 larvae L-1 , and aquariums had different colors, and were: green and blue (light colors); brown and black (dark colors). The final development; survival, total and standard length, weight and biomass of the larvae were similar in all colored aquaria. The highest mortality occurred during the first days after hatching, declining over the period, when it is observed the larval development, indicating that care should be necessary in the first few days. During cleaning handling, the accidental catch of larvae was higher in black aquariums. In the first days of life, due to the fragility of the larvae, it is possible to verify that between the second and third day occur the greatest mortalities. The number of accidentally captured larvae was lower than the mortality, suggesting that the high mortality in early larval life is not influenced by the handler management. The catfish L. alexandri larvae should be cultivated in aquariums that allow a good contrast between the larvae and the background, to avoid accidental capture of larvae by the handler. It is suggested to avoid the use of dark and black aquariums.

Resumo O objetivo deste experimento foi avaliar o efeito de diferentes cores de aquários no desempenho e sobrevivência das larvas do bagre Lophiosilurus alexandri , bem como sobre a capacidade visual do tratador. As larvas foram colocadas em estocadas em 5 L-aquários na densidade de 7 larvas L-1, e aquários apresentaram cores diferentes e foram distribuídos a seguir: verde e azul (cores claras); marrom e preto (cores escuras). O desempenho final; a sobrevivência, comprimento total e padrão, peso e biomassa das larvas foram semelhantes entre os aquários coloridos. A maior mortalidade ocorreu durante os primeiros dias após a incubação, em declínio ao longo do período, quando se observa o desenvolvimento larval, indicando que os cuidados devem ser redobrados nos primeiros dias. Durante o manejo de limpeza, a captura acidental de larvas foi maior nos aquários pretos. Nos primeiros dias de vida, devido à fragilidade das larvas, é possível verificar que entre o segundo e o terceiro dia ocorrem as maiores mortalidades. O número de larvas capturadas acidentalmente foi menor do que a mortalidade, sugerindo que a alta mortalidade na vida larval não é influenciada pelo manejo do manipulador. As larvas de bagre L. alexandri devem ser cultivadas em aquários que permitem um bom contraste entre as larvas e o fundo, para evitar a captura acidental de larvas pelo manipulador. Sugere-se que evite o uso de aquários escuros e pretos.

GROWTH, HUSBANDRY, AND DIETS OF FIVE SUCCESSFULLY HAND-REARED ORPHANED GIRAFFE CALVES (GIRAFFA CAMELOPARDALIS ROTHSCHILDI AND GIRAFFA CAMELOPARDALIS RETICULATA).

Giraffe in the wild are in ongoing decline because of poaching and habitat loss and fragmentation, and were recently assessed as "vulnerable" on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Captive breeding and saving each individual are therefore becoming more important to save this species from extinction. This paper describes the husbandry and diets of successfully hand-reared Rothschild's giraffes (Giraffa camelopardalis rothschildi; n = 3) and reticulated giraffes (Giraffa camelopardalis reticulata; n = 2). All calves were initially fed with bovine colostrum followed by cow's milk (Holstein milk; Holstein milk with 10% of bovine colostrum; Jersey and Guernsey milk). Additionally, lactase enzymes (Lactaidt, Johnson & Johnson Inc., Guelp, Ontario N1K1A5, Canada) and probiotics (Probiost, Vets Plus, Inc., Menomonie, WI 54751, USA) were used. Average growth varied from 764 to 1,239 g/day from birth until 2 mo of age and between 508 and 1,161 g/day from birth until last measurement before weaning. Hand-reared calves gained up to 21 cm in height within the first month and 82-138% of their birth weight during the first 2 mo. The giraffes were weaned at 6 (n = 1), 8 (n = 3), and 11.5 (n = 1) mo and successfully socialized and introduced to other giraffes. The described diets and husbandry proved to be effective in all five calves. Large amounts of cow's milk per feeding (up to 6 L) did not result in gastrointestinal problems.

Accidentally catching of the catfish Lophiosilurus alexandri (Steindachner, 1876) larvae in aquariums with different colors.

The aim of this study was to evaluate the effect of different colors in development and survival of catfish Lophiosilurus alexandri larvae, as well as over the visual ability of the handler. Larvae were placed in 5 L-aquariums at a density of 7 larvae L-1 , and aquariums had different colors, and were: green and blue (light colors); brown and black (dark colors). The final development; survival, total and standard length, weight and biomass of the larvae were similar in all colored aquaria. The highest mortality occurred during the first days after hatching, declining over the period, when it is observed the larval development, indicating that care should be necessary in the first few days. During cleaning handling, the accidental catch of larvae was higher in black aquariums. In the first days of life, due to the fragility of the larvae, it is possible to verify that between the second and third day occur the greatest mortalities. The number of accidentally captured larvae was lower than the mortality, suggesting that the high mortality in early larval life is not influenced by the handler management. The catfish L. alexandri larvae should be cultivated in aquariums that allow a good contrast between the larvae and the background, to avoid accidental capture of larvae by the handler. It is suggested to avoid the use of dark and black aquariums.

Seasonal changes in circulating gonadal steroid levels and physiological evidence for the presence of intrinsic circannual reproductive cycles in captive finless porpoises Neophocaena asiaeorientalis from the western Inland Sea, Japan.

We monitored annual fluctuations of gonadal steroid levels in three sexually mature captive finless porpoises (Neophocaena asiaeorientalis; two males and one female) from two different facilities over 56-91 months. Two animals (one male and one female) were held in an indoor tank with a sunroof (facility A) and the other male was held in an indoor tank without a sunroof (facility B). Water temperatures in both facilities reflected seasonal changes during the study period with a minor difference in the fluctuation pattern. Testosterone levels of the male in facility A were higher from spring to summer every year and exhibited a 12-month cycle. The female showed estrus cycles in 1-month intervals from summer to winter, excluding 2 anestrus years. In contrast, the period of higher testosterone levels of the male in facility B gradually initiated earlier over the years under a constant photoperiod (11.5L:12.5D) and exhibited a 9-month cycle during the first 52 months. After changing the light conditions to a natural photoperiod, its testosterone levels were high from early spring to summer for 3 consecutive years and exhibited a 12-month cycle. Our results showed that under a constant artificial photoperiod, the male in facility B failed to recognize the seasonal changes of a natural external environment, resulting in a 9-month, free-running hormone cycle.

Variation in food availability mediate the impact of density on cannibalism, growth, and survival in larval yellow spotted mountain newts (Neurergus microspilotus): Implications for captive breeding programs.

In this study, we examined cannibalistic behavior, growth, metamorphosis, and survival in larval and post-metamorph endangered yellow spotted mountain newts Neurergus microspilotus hatched and reared in a captive breeding facility. We designed a 2 × 2 factorial experiment, crossing two levels of food with two levels of density including high food/high density, high food/low density, low food/high density, and low food/low density. The level of cannibalistic behavior (including the loss of fore and hind limbs, missing toes, tail, gills, body damage, and whole body consumption) changed as the larvae grew, from a low level during the first 4 weeks, peaking from weeks 7 to 12, and then dropped during weeks 14-52. Both food level and density had a significant effect on cannibalism. The highest frequency of cannibalism was recorded for larvae reared in the low food/high density and lowest in high food/low density treatments. Growth, percent of larval metamorphosed, and survival were all highest in the high food/low density and lowest in low food/high density treatment. Food level had a significant effect on growth, metamorphosis, and survival. However, the two levels of density did not influence growth and metamorphosis but showed a significant effect on survival. Similarly, combined effects of food level and density showed significant effects on growth, metamorphosis, and survival over time. Information obtained from current experiment could improve productivity of captive breeding facilities to ensure the release of adequate numbers of individuals for reintroduction programs. Zoo Biol. 35:513-521, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.

Postnatal growth and age estimation in Scotophilus kuhlii.

Adequate postnatal growth is important for young bats to develop skilled sensory and locomotor abilities, which are highly associated with their survival once independent. This study investigated the postnatal growth and development of Scotophilus kuhlii in captivity. An empirical growth curve was established, and the postnatal growth rate was quantified to derive an age-predictive equation. By further controlling the fostering conditions of twins, the differences in the development patterns between pups that received maternal care or were hand-reared were analyzed to determine whether the latter developed in the same manner as their maternally reared counterparts. Our results indicate that both forearm length and body mass increased rapidly and linearly during the first 4 weeks, after which the growth rate gradually decreased to reach a stable level. The first flight occurred at an average age of 39 days with a mean forearm length and body mass of 92.07% and 70.52% of maternal size, respectively. The developmental pattern of hand-reared pups, although similar to that of their maternally reared twin siblings, displayed a slightly faster growth rate in the 4th and 5th weeks. The heavier body mass of hand-reared pups during the pre-fledging period may cause higher wing loading, potentially influencing the flight performance and survival of the bats once independent.

Effect of feeding graded levels of crude protein on nutrient utilization and feather growth in Lady Amherst's pheasants.

In order to find out the optimum level of crude protein (CP) in the diet of captive Lady Amherst's pheasants (LAP) on molt, 18 male birds were randomly distributed into three groups of six each in an experiment based on completely randomized block design. The CP content of the diets of birds in groups I, II, and III was 13.4, 16.5, and 19.1%, respectively. Intake and apparent balance of nitrogen increased linearly (P < 0.001) as CP content of the diet increased. Intake and utilization of energy, calcium, and phosphorous were similar among groups. Body mass change and growth rate of feathers were significantly (P < 0.01) lower in group I as compared to groups II and III. There was a positive co-relationship between ME intake and change in body weight (R(2) = 0.89, F = 126.4, P < 0.001). Regression analysis indicates that LAP can maintain body mass when ME supply is 122.2 Kcal/kg BW(0.75)/d. Linear relationships between intake and apparent retention of N, Ca, and P as expressed on mg/kg BW(0.75)/d were all significant. Apparent nitrogen retention, and mean feather growth rate was lower in birds fed diet containing 13.4% CP. Feeding of the diets containing 16.5% CP resulted in improved retention of nitrogen, and mean feather growth rate. Further increase in dietary concentration of CP to 19.1% showed no further improvement. It was concluded that a diet containing 16.5% CP would be optimum for Lady Amherst's pheasants during molt.

Seasonal acclimatization determined by non-invasive measurements of coat insulation.

Seasonal acclimatization in terrestrial mammals in the Northern Hemisphere involves changes in coat insulation. It is more economical to provide increased insulation than increased heat production for protection against the cold. This study was done to test a technique for the non-invasive measurement of mammal coat insulation and to measure coat insulation over several seasons on captive exotics. The working hypothesis was that species that have no coat or have a coat that does not change seasonally do not acclimatize seasonally. Three surface temperature readings were measured from the torso area. The insulation was calculated using measured metabolic rates and body temperature when possible. The African elephants, giraffe and okapi did not acclimatize with average maximum insulation values of 0.256°Cm(2) W(-1) . The Amur tigers and mountain goats acclimatized to seasonal ambient conditions by increasing the insulation values of the hair coats in the cold with an average maximum insulation values of 0.811°Cm(2) W(-1) . The cold adapted species are more than three times more insulated in the cold than the equatorial species. The husbandry implications of exotics that have no ability to acclimatize to Northern Hemisphere seasonal ambient changes are profound. Giraffe, African elephants, and okapi when exposed to cold conditions with ambient air temperatures below 21°C will use body energy reserves to maintain a heat balance and will require housing that provides ambient conditions of 21°C.

Optimal husbandry of hatchling Eastern Indigo Snakes (Drymarchon couperi) during a captive head-start program.

Optimal husbandry techniques are desirable for any headstart program, but frequently are unknown for rare species. Here we describe key reproductive variables and determine optimal incubation temperature and diet diversity for Eastern Indigo Snakes (Drymarchon couperi) grown in laboratory settings. Optimal incubation temperature was estimated from two variables dependent on temperature, shell dimpling, a surrogate for death from fungal infection, and deviation of an egg from an ovoid shape, a surrogate for death from developmental anomalies. Based on these relationships and size at hatching we determined optimal incubation temperature to be 26°C. Additionally, we used incubation data to assess the effect of temperature on duration of incubation and size of hatchlings. We also examined hatchling diets necessary to achieve optimal growth over a 21-month period. These snakes exhibited a positive linear relationship between total mass eaten and growth rate, when individuals were fed less than 1711 g of prey, and displayed constant growth for individuals exceeding 1711 g of prey. Similarly, growth rate increased linearly with increasing diet diversity up to a moderately diverse diet, followed by constant growth for higher levels of diet diversity. Of the two components of diet diversity, diet evenness played a stronger role than diet richness in explaining variance in hatchling growth. These patterns document that our goal of satiating snakes was achieved for some individuals but not others and that diets in which total grams consumed over the first 21 months of life is distributed equivalently among at least three prey genera yielded the fastest growth rates for hatchling snakes.

Growth rates in a captive population of Tonkean macaques.

Measuring variations in body mass is necessary to gain a deeper understanding of the evolution of life-history patterns, and it provides information on the timing of sexual maturity and the development of sexual dimorphism. In this study, we collected longitudinal data on body mass from infancy to adulthood in a captive population of Tonkean macaques (Macaca tonkeana). Tests to evaluate whether social group, maternal age, and dominance rank influenced growth rates showed that they had no significant effect. We investigated the timing and magnitude of breaking points in the growth paths of males and females, and checked whether these breaking points could correspond to specific reproductive and morphological developmental events. We found that male and female Tonkean macaques have roughly equivalent body masses until around the age of four, when males go through an adolescent growth spurt and females continue to grow at a constant rate. Males not only grow faster than females, but they also continue to grow for nearly one and a half years after females have attained their full body mass. Growth rate differences account for approximately two-thirds of the body mass sexual dimorphism; only the remaining third results from continued male growth beyond the age where full body mass is reached in females. We also discovered remarkable correspondences between the timing of testicular enlargement and the adolescent growth spurt in males, and between dental development and slowdown breaking points in both sexes.

Cross-fostering in gray wolves (Canis lupus lupus).

Cross-fostering in canids, with captive-bred pups introduced into endangered wild populations, might aid conservation efforts by increasing genetic diversity and lowering the risk of inbreeding depression. The gray wolf (Canis lupus lupus) population in Scandinavia suffers from severe inbreeding due to a narrow genetic base and geographical isolation. This study aimed at evaluating the method to cross-foster wolf pups from zoo-born to zoo-born litters. The following was assessed: female initial acceptance of foster pups, growth rate in relation to age difference between foster pups and pups in recipient litters and survival over the first 33 weeks. The study included four litters added by two foster pups in each. The age differences between the foster pups and the recipient litters were 2-8 days. After augmentation, all four females accepted the foster pups, demonstrated by her moving the entire litter to a new den site. Growth rate was dependent on the age difference of the pups in the foster litters, with a considerably slower growth rate in the 8 days younger pups. However, these pups later appeared to be at no disadvantage. Foster pups had a higher survival rate than females' pups, however, the causes of death were probably not kin or non-kin related. The results indicate that cross-fostering works in gray wolves and that this might be a plausible way to increase genetic variation in the wild population.

Body mass dynamics in hand reared clouded leopard (Neofelis nebulosa) cubs from birth to weaning.

To study the dynamics of body mass changes in hand reared clouded leopards, we analyzed 3,697 weight data points during the first 3 months of life in 49 cubs from 24 zoo-born litters from 2003 through 2012. All cubs were fed the same formula mixture after a similar weaning protocol. The hand rearing process was divided into three periods based on feeding protocols: Stage 1: formula only (Days 1-28; Day 0 = day of birth); Stage 2, formula supplemented with protein (e.g., turkey baby food; Days 29-42); Stage 3, formula in decreasing amounts supplemented with meat (chicken and/or beef; Days 43-90). Weights at birth were 11.2% higher (P < 0.001) for males (n = 29) than females (n = 20). Daily weight gain was slowest (P < 0.05) during Stage 1 when cubs were fed straight formula only and fastest during Stage 3 when provided a mixture of formula and meat. Mean growth rate (± SD) during hand rearing differed (P < 0.05) by gender, being 34.6 ± 1.4 g/day for male and 30.0 ± 1.2 g/day for female cubs. Eighteen cubs (37%) exhibited mild to severe diarrhea during the study; however, palliative treatment resulted in similar (P > 0.05) growth and weaning weights compared to healthy counterparts. These are the first data documenting, on a large scale, the growth patterns for zoo born, hand reared clouded leopard cubs. Findings are valuable as an aid in managing this rare species, including for helping identify early onset of medical issues and further determining key factors regulating the first 3 months of development.

Suckling behavior in Eurasian lynx (Lynx lynx L.) cubs: characteristics and correlation with competitive interactions.

There is substantial evidence in the literature that the offspring of many mammal species prefer a particular pair of nipples. There is also a definite "nipple order" in individual litters in which each young predominantly uses one or two particular nipples. In combination with early competitive interactions, such "constancy" can play an important role in the social development of the young. In this study, we reveal an unequal use of different pairs of mothers' nipples by 42 Eurasian lynx cubs in 16 litters and investigate the relationship of this phenomenon with the early competitive interactions of the cubs and their physical development. For the lynx cubs, the most often used pair of nipples is the middle pair. There is also definite "nipple order" in each litter. We found a negative correlation between nipples use by the offspring and their competitive activity. No influence of "nipple order" on the cubs' growth rate was detected.

Early development and growth in captive-born Iberian lynx (Lynx pardinus).

Knowledge on the growth and early development patterns of endangered species can become a useful conservation tool because it may allow detecting anomalous growth in newborns, both in captivity breeding and in the wild. We studied the growth and early development of 40 Iberian lynx (Lynx pardinus) cubs belonging to 21 litters born in captivity between 2005 and 2012 at "El Acebuche" Iberian Lynx Breeding Centre. This is the first study on growth in this critically endangered species. The Iberian lynx cubs were not fully developed at birth. During the first 3 weeks of life, cubs underwent many of the physical changes that allowed them to improve their interaction with the environment, such as the opening of eye and auditory channels, teeth eruptions, and the ability to walk. When the cubs were 1 month old, they were ready to leave the den and develop new behaviors such as the exploration of their environment, play, or hunt. Three different models had been fitted to the body mass growth of the Iberian lynx. The von Bertalanffy curve provided the best fit. The asymptotic adult mass was the only parameter that differed between males and females (males being 8% larger), due to the higher growth rate of males. The adult weight of hand-reared cubs (i.e., those abandoned at born) did not differ from that of cubs reared by their mothers. Both growth and development showed differences from other lynx species.

Physiological indices of stress in wild and captive garter snakes: correlations, repeatability, and ecological variation.

Glucocorticoids and leukocyte ratios have become the most widespread variables employed to test hypotheses regarding physiological stress in wild and captive vertebrates. Little is known, however, regarding how these two indices of stress covary in response to stressors, their repeatability within individuals, and differences in response time upon capture. Furthermore, few studies compare stress indices between captive and wild populations, to assess potential alteration of stress physiology in captivity. To address these issues, we examined corticosterone (CORT) and heterophil to lymphocyte (H:L) ratios in two ecotypes of the garter snake Thamnophis elegans. We found that CORT and H:L ratios were not correlated within individuals, and both variables showed little or no repeatability over a period of months. CORT levels, but not H:L ratios, were higher for individuals sampled after 10min from the time of capture. However, both variables showed similar patterns of ecotypic variation, and both increased over time in gravid females maintained in captivity for four months. We suggest that CORT and H:L ratios are both useful, but disparate indices of stress in this species, and may show complex relationships to each other and to ecological and anthropogenic variables.

Effect of age and ration on diet-tissue isotopic (Δ13C, Δ15N) discrimination in striped skunks (Mephitis mephitis).

An important prerequisite for the effective use of stable isotopes in animal ecology is the accurate assessment of isotopic discrimination factors linking animals to their diets for a multitude of tissue types. Surprisingly, these values are poorly known in general and especially for mammalian carnivores and omnivores in particular. Also largely unknown are the factors that influence diet-tissue isotopic discrimination such as nutritional quality and age. We raised adult and juvenile striped skunks (Mephitis mephitis) in captivity on a constant omnivore diet (Mazuri Omnivore A 5635). Adults (n=6) and juveniles (n=3) were kept for 7 months and young (n=7) to the age of 50 days. We then examined individuals for stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope values of hair, nails, lipid, liver, muscle, bone collagen and the plasma, and cellular fractions of blood. Discrimination values differed among age groups and were significantly higher for young compared with their mothers, likely due to the effects of weaning. Δ(15)N isotopic discrimination factors ranged from 3.14 (nails) to 5.6‰ (plasma) in adults and 4.3 (nails) to 5.8‰ (liver) for young. For Δ(13)C, values ranged from-3.3 (fat) to 3.0‰ (collagen) in adults and from-3.3 (fat) to 2.0‰ (collagen) in young. Our data provide an important tool for predicting diets and source of feeding for medium-sized mammalian omnivorous adults integrated over short (e.g. liver, plasma) through long (e.g. collagen) periods and underline the potential effects of age on isotopic values in omnivore diets.