Body size and fatness of free-living baboons reflect food availability and activity levels

We used morphometric techniques and isotope-labeled water to investigate the influence of abundant, accessible food and resultant low activity levels on body size and fatness in free-living adolescent and adult baboons as compared to animals in the same population that experienced more typical, wild-feeding conditions. Females that had access to abundant food from a nearby garbage dump averaged 16.7 kg body mass, 50% more than their wild-feeding counterparts in adjacent home ranges. Little of the difference was due to lean mass: the animals with an accessible abundance of food averaged 23.2% body fat in contrast to 1.9% for the wild-feeding animals. Significant differences between feeding conditions were found for all measured skinfolds and for upper arm circumference but not for linear measurements. Differences between feeding conditions were less for males than for females, perhaps reflecting persistent effects of nutritional conditions during the first eight years of life before dispersal from the group of birth. The difference in fatness between feeding conditions was similar to the difference between humans with frank obesity and those that are considered lean, but in both cases the percentages of body fat in the baboons were considerably less than those observed in humans. In levels of fatness, the relatively sedentary animals resembled their counterparts in group-housed captive conditions. © 1993 Wiley-Liss, Inc.     

Living near the limits: Effects of interannual variation in food availability on diet and reproduction in a temperate primate,the Taihangshan macaque (Macaca mulatta tcheliensis)

Nutrient intake of animals is influenced by an interplay of external and internal factors, such as food availability and reproductive state, respectively. We used the nutritional geometry framework to analyze individual-based data on energy and nutrient intake in relation to reproductive state in a population of rhesus macaques (Macaca mulatta tcheliensis), which live in a harsh high-latitude habitat, the Taihangshan mountains of China, and exhibit strong reproductive seasonality. We combined data over a 3-year period on food availability, diets, reproductive output, and components of maternal investment to understand how Taihangshan macaques respond to variation in food availability and nutrition in reproduction. Our results show there was high interannual variation in availability of an important staple source of fat and carbohydrates (nonprotein energy), seeds of oak (Quercus spp). Despite this variability in seed availability skewing the dietary macronutrient ratios considerably (from 12.96% to 30.12% dietary energy from protein), total metabolizable energy intake was maintained across years during pregnancy. Lactating females had higher mean daily energy intakes than pregnant females. As in pregnant females, energy intake was maintained constant across years, but only when seed availability enabled the contribution of available protein to energy intake to be maintained between 15.32% (2013) and 17.97% (2015). In 2014, when seeds were scarce, lactating females had a shortfall in energy intake compared with 2013 and 2015. This corresponded with a reduction in the number of females giving birth (11 out of 23), but there was no interannual difference in survival rates. Compared to 2013 and 2015, in 2014 females had greater weight loss (drew on body reserves), moved less, and spent more time nursing their offspring. We discuss implications of these results for range limitation in Taihangshan macaques.     

Effects of Reproductive Status on Energy Intake,Ingestion Rates,and Dietary Composition of Female <Emphasis Type="BoldItalic">Cebus capucinus</Emphasis> at Santa Rosa,Costa Rica

The limiting factor for fitness in female primates is the acquisition of high-quality food, i.e., food that is high in energy and nutrients, such as protein, fat, and carbohydrates. Reproductive status can influence female feeding patterns, e.g., lactating females in some primate species consume greater quantities of food and specific nutrients than do nonlactating females. We examined the energy intake, ingestion rate, and composition of the diet in female white-faced capuchins in 3 reproductive states: lactating, gestating, and cycling. We observed 12 reproductively active females for 7 mo and compared their energy intake, ingestion rates, and intake rates of nutrients: protein, fat, sugar, and fiber. Lactating females took in significantly more energy per hour while feeding than pregnant and cycling females did. Lactating females also ingested significantly more food items per hour, but they did not spend more time eating than other females did, and they did not differ in the composition of their diet as measured by insect consumption and proportion of protein. Pregnant and cycling females did not differ from each other in any of the measures. We predicted that as the infants aged and began to move independently to forage and play, their mothers’ energy intake rates would decrease in concert with decreased energy demands by the infant. We found a statistically significant relationship between these 2 factors, with infant age explaining 75.4% of variation in mothers’ energy intake, supporting previous studies that found lactation to be the most energetically expensive reproductive state.     

Activity budgets of wild female chimpanzees in different reproductive states

Activity budgets of wild female chimpanzees (Pan troglodytes schweinfurthii) when lactating were compared with those during estrus and anestrus. Five anestrous females, seven estrous females, and three lactating females in Mahale Mountains National Park, Tanzania, were the subject of focal sampling. Time spent for feeding, resting, and moving was examined. For each of these three categories of activity, there was no significant difference of time spent for each activity between lactating females and either estrous or anestrous females. The females spent about 30% of their daytime feeding, about 40% resting, and about 30% moving. One of the reasons for the lack of difference might be the type of parties that females attended when they were observed. In most cases, the females were seen in large bisexual parties. Although lactating females are expected to need more nutrition than cycling females and this might affect their activity budget, the party type they attended might also affect the budget. Received: January 17, 2000 / Accepted: June 22, 2000     

Effects of age and sex on intra-group spacing behaviour in juvenile savannah baboons,Papio cynocephalus cynocephalus

Twenty juvenile members of known genealogies in two baboon groups were studied over a 16-month period to evaluate a number of predictions about juvenile spacing behaviour based on the natural history of savannah baboons. Young juveniles (1–2·5 years old) approached more frequently and spent more time in proximity to other group members than did old juveniles (3–5·5 years old). In particular, young juveniles associated more closely with their mothers, particular adult males (possible fathers) and age-peers than did old juveniles. Approaches of young juveniles towards unrelated, high-ranking adults were more likely to occur during feeding than were those of old juveniles. Also, following such an approach, young juveniles were more likely than old juveniles to begin feeding immediately. The overall rates of feeding of old juveniles were depressed when they were in proximity to unrelated, high-ranking adults, whereas the feeding rates of young juveniles were not. Juvenile males approached adult males more often than did juvenile females. Juvenile females approached unrelated adult females more often than did juvenile males. Sex differences also existed in juveniles' choices of unrelated adult female neighbours. Juvenile females associated most often with lactating females, whereas juvenile males associated primarily with cycling females. During group resting, juvenile females approached adult females from higher-ranking matrilines more often than they approached adult females from lower-ranking matrilines. Juvenile males did not exhibit this attraction. Also, among old juveniles, females associated closely with their mothers, whereas males did not. Taken together, the results support the hypotheses that juvenile baboons associate with group members in ways that (1) enhance the probability of surviving an early period of high mortality, (2) create opportunities for social learning of sex-typical behaviours/skills, and, for females, (3) facilitate acquisition of familial dominance status.     

Nutritional requirements for maintenance of body weight and fat deposition in the long-distance migratory garden warbler, Sylvia borin (Boddaert)

Intake of food, protein, fat and carbohydrates and their fecal output and the birds' weights were recorded during different feeding trials with specific nutrient reduced diets in the old-world long-distance migratory garden warbler. The birds' body weights were affected by low dietary protein as well as low dietary fat levels. Low dietary protein and fat levels were associated with significant changes in daily gross and net food intake and in the efficiency of food and nutrient utilization. Birds fed on diets with low nutrient levels for an extended length of time recovered in weight after an initial weight loss. They obviously compensated the restricted nutrient levels primarily by increasing the daily food intake and by changing the efficiency of food and nutrient utilization. Effects of restricted dietary nutrient levels on body weight and adaptation depended on the previous composition of the food. The average daily net fat intake was much higher than the average daily net protein intake, both for maintenance of a constant body weight and for successful regain of weight. The data were further discussed with respect to the role of a fruit diet in omnivorous passerine birds.     

A comparison of primiparous and multiparous mother-infant dyads inMacaca mulatta

The relationships of 42 rhesus monkey mother-infant dyads were examined to investigate the effects of the mothers' parity. Primiparous mothers were found to be younger, more excitable and less confident than the multiparous mothers. They also received more aggression from other adult females living in their social group and were more anxious about their infants, approaching and leaving them more frequently. The primiparous mothers protected their daughters more than the multiparous mothers and their daughters correspondingly spent more time in the ventro-ventral position and more time on the nipple. Their sons however spent less time in contact with their mothers than did the sons of the multiparous mothers. Although the primiparous mothers protected their daughters more than their sons, for the multiparous mothers the converse was true and sons received more maternal protection. It is suggested that the greater protectiveness of the multiparous mothers towards male infants may be a consequence of the interest siblings have in males, whereas the greater protectiveness of primiparous mothers to daughters may stem from their greater vulnerability to attacks from adult females. The importance of mother-mediated sibling influences may explain the lack of strong parity differences in previous studies.     

Increase in tannin consumption by sifaka (<Emphasis Type="Italic">Propithecus verreauxi verreauxi</Emphasis>) females during the birth season: a case for self-medication in prosimians?

In this study we report preliminary data on the consumption of tannin-rich plants by sifakas (Propithecus verreauxi verreauxi) living in the Kirindy forest, western Madagascar. Sifakas spent most of their time feeding on only a few plant species. The tannin intake during the period between the pregnancy and birth season was significantly higher in pregnant females or females with lactating infants than in non-reproductive females and males. These periparturient females secured a larger proportion of condensed tannins by short feeding bouts on plants not included in the group's limited preferred food species. The measured increase in tannin intake is puzzling in light of the fact that tannins are commonly known for their protein-binding properties. Since protein demands are highest in pregnant and lactating females, possible medicinal benefits of tannin ingestion are considered. Tannin consumption is associated with an increase in body weight and stimulation of milk secretion. Veterinarians administer tannins as an astringent, anti-hemorrhagic and anti-abortive. Their high potential as an alternative anthelminthic has also recently been recognized. Thus, when viewed as self-medicating behavior, controlled increase in tannin intake could have multiple prophylactic advantages for females during the periparturient period. The high selectivity in their plant choice, and the presence of unusual feeding habits by a particular group of individuals (females with infants) limited in time (birth season), suggests that an increase in tannin ingestion may be a self-medicating behavior with multiple directly adaptive benefits to female reproduction. Electronic Publication     

Influence of Human Food Consumption on the Time Budget of Vervets

In nonhuman primate groups that utilize crop and food-raiding strategies, the inclusion of human food in the diet can have a pervasive impact on the activity budget. Human food is usually of higher quality and energy per unit than wild food. Thus, metabolic demands may be reached sooner on a human food diet, which in turn leads to improved foraging efficiency. In particular, a reduction in time spent feeding is associated with an increase in time spent resting. We investigated changes in time budget in a group of vervets (Chlorocebus aethiops pygerthrus) living in a tourist and cultivated area of Entebbe, Uganda (Zoo group). Saj collected 123 hr of focal observations on 17 individuals. Human food constituted half of the diet of Zoo group. Access to human food resulted in a high proportion of time resting and a low proportion of time feeding. The group had a small average daily range and a small home range in relation to other reports on unprovisioned groups. The time budget differences suggest that the juveniles spent more time moving and feeding and less time resting than adults did, and that adult females were more social than adult males were. These patterns have been observed in both provisioned and unprovisioned vervet groups. In contrast to a report from an unprovisioned group (Harrison, 1983), lactating females in this provisioned situation were able to maintain feeding and activity levels similar to those of other adults. However, adult females spent significantly less time consuming human food than juveniles did. We suggest that the risk associated with human food consumption may explain the low consumption of human food by females with dependent offspring. The differences may also reflect the different nutritional requirements of lactating females or the tendency for juveniles to be more exploratory than other group members.     

The energetics of lactation in cooperatively breeding meerkats Suricata suricatta

Species may become obligate cooperative breeders when parents are unable to raise their offspring unassisted. We measured the daily energy expenditure of mothers, helpers and offspring during peak lactation in cooperatively breeding meerkats Suricata suricatta using the doubly labelled water technique. Lactating mothers expended more energy per day than allo-lactating subordinate females, non-lactating females or suckling offspring. Metabolizable energy intakes of lactating mothers were calculated from isotope-based estimates of offspring milk energy intake, and were not significantly different from the previously suggested maximal limit for mammals. Allo-lactating females were the only category of animals that lost weight during the period of study, probably because they spent more time babysitting than non-lactating females. Daily energy expenditure (DEE) of lactating mothers increased with litter size but decreased with the number of helpers. Calculations show that for every 10 helpers, even in the absence of allo-lactators, mothers are able to reduce their DEE during peak lactation by an amount equivalent to the energy cost of one pup. These results indicate that helpers have beneficial energetic consequences for lactating mothers in an obligate cooperatively breeding mammal.     

Parity of female goats does not influence their estrous and ovulatory responses to the male effect

The objective of the present study was to determine whether parity is a factor that influences the estrous and ovulatory responses of female goats when they are stimulated by males that show increased sexual activity. To stimulate sexual activity, four adult male goats were subjected to photoperiodic treatment for 2.5 months comprising long days, with the treatment commencing on 1 November. On 14 April at 1900 h, a group of multiparous females (n = 21) and a group of 16 months-old nulliparous females (n = 19) were exposed to four bucks (two per group) for 15 days. Throughout the study period, the estrous behavior of these female goats was detected twice on a daily basis. Ovulations of the female goats were determined by ecography on days 7 and 18 after exposure to males. The sexual behavior of males was recorded twice every day from 0800 to 0900 h and from 1730 to 1830 h during the first 4 days after introduction in the pen of females. The total cumulative proportion of multiparous females that had ovulations (100%) and displayed estrous behavior (100%) during the 15 days of exposure to males did not differ (P > 0.05) from that of nulliparous females (100% and 95%, respectively). The interval between introduction of males and onset of estrous behavior did not differ (P > 0.05) between multiparous (1.9 ± 0.1 days) and nulliparous (1.7 ± 0.2 days) females. The proportion of females displaying a short estrous cycle was greater (P < 0.05) in multiparous (13/21, 62%) than in nulliparous (5/19, 26%) females. Duration of these shorter than typical estrous cycles did not differ (P > 0.05) between groups (multiparous: 5.2 ± 0.3 days, nulliparous: 4.5 ± 0.1 days). The number of anogenital sniffings was greater (P < 0.001) in males exposed to nulliparous than in those exposed to multiparous females. In contrast, the number of mounting attempts was greater (P < 0.01) in males that were introduced to multiparous than in those that were introduced to nulliparous does. The number of flehmen, nudging, self-marking with urine, and mounts was not different (P > 0.05) between males that were in contact with multiparous and nulliparous females. These results indicate that regardless of parity, female goats respond to male introduction if they are stimulated by males that were previously exposed to artificial long days to increase their sexual behavior.     

Social and seasonal influences on the reproductive cycle in female mandrills (Mandrillus sphinx)

We present 12 years of perineal swelling data for a semifree-ranging colony of mandrills (Mandrillus sphinx), and evaluate the influence of rank, parity, and seasonality on reproductive parameters. Female sexual swellings showed a seasonal pattern, with August the median month of ovulation. Overlapping periovulatory periods did not decrease the likelihood of conception. Females showed their first genital swelling at age 3.6 years (n = 28; range, 3.2-4.6 years), and higher-ranking females experienced their first swelling earlier than low-ranking females. Median postpartum amenorrhea (PPA) duration was 208 days (n = 92; range, 74-538 days). PPA was longer in primiparous females than in multiparous females, but PPA duration was unrelated to female rank. Median follicular phase duration was 24 days for the first cycle after parturition (n = 84; range, 12-40 days), shortening to 17 days in subsequent cycles (n = 55; range, 6-39 days). The follicular phase was longer in nulliparous females than in parous females, but was unrelated to female rank. Median cycle length (from one sexual swelling breakdown to the next) was 38 days (n = 57; range, 18-108 days). Eighty-seven percent of conceptions occurred within two cycles, and half of the nulliparous females conceived during their first swelling cycle. Lower-ranking females were more likely to require more cycles to conceive than higher-ranking females. The cycling phase was significantly longer in nulliparous females than in parous females, and was also significantly longer in lower-ranking females than in higher-ranking females. We discuss the influence of provisioning on female reproductive parameters, the influence of parity and rank on the different phases of the interbirth interval, and the evolution of long and variable follicular phases in mandrills.     

Effects of different amounts and type of diet during weaning-to-estrus interval on reproductive performance of primiparous and multiparous sows

During weaning-to-estrus interval (WEI), the sows are usually fed with high feed level to improve the reproductive performance. However, the WEI has been reduced over the years which may reduce the impact of feed level on performance in the modern genetic lines. The aim of this study was to evaluate the effect of two feeding levels (moderate feeding level (MFL): 2.7 kg/day and high feeding level (HFL): 4.3 kg/day) and two diet types (gestation: 13.67 MJ/kg of metabolizable energy (ME) and 0.62% of standard ileal digestible lysine (SID Lys) and lactation: 14.34 MJ ME/kg and 1.20% of SID Lys) offered during the WEI on reproductive performance. In total, 19.0% of sows were excluded from the analysis due to feed intake below 75% (9.6% and 28.5% in MFL and HFL groups, respectively), remaining 254 primiparous and 806 multiparous sows. Follicular size and change in BW were measured in subsamples of 180 and 227 females, respectively. Data were analyzed considering the sow as the experimental unit. Feeding level, diet type, parity and their interactions were included as fixed effects, whereas the day of weaning was considered as a random effect. The feed intake of MFL and HFL groups averaged 2.5 ± 0.02 and 3.8 ± 0.02 kg/day, respectively. There was an interaction between feeding level and parity for daily feed intake. Within HFL, multiparous sows consumed 181 g/day more than primiparous sows (P < 0.01), but no difference was observed within MFL (P > 0.05). Both primiparous and multiparous sows lost proportionally less weight when fed HFL than MFL gestation diet during WEI. The percentage of weight loss was lower in HFL than in the MFL group in multiparous sows fed the lactation diet. The WEI was not affected by feeding level, diet type or its interaction (P > 0.05), but it was longer in primiparous than in multiparous sows (P = 0.001). There was no effect of feeding level, diet type, parity or their interactions on anestrus and farrowing rates. Multiparous sows showed greater follicular size, and greater numbers of total born and born alive piglets in the subsequent cycle than primiparous sows (P < 0.05). In conclusion, feeding weaned primiparous and multiparous sows with 4.3 kg/day of a gestation (58.78 MJ ME and 26.66 g SID Lys) or a lactation diet (61.66 MJ ME and 51.60 g SID Lys) does not improve follicular size and reproductive performance in the subsequent cycle.     

Foraging behaviour at multiple temporal scales in a wild alpine equid

Forage abundance, forage quality, and social factors are key elements of the foraging ecology of wild herbivores. For non-ruminant equids, forage-limited environments are likely to impose severe constraints on their foraging behaviour. We used a multi-scale approach to study foraging behaviour in kiang (Equus kiang), a wild equid inhabiting the high-altitude rangelands of the Tibetan Plateau. Using behavioural observations and vegetation sampling, we first assessed how patterns of plant abundance and quality affected (i) the instantaneous forage intake rate (fine scale) and (ii) the proportion of time spent foraging (coarse scale) across seasons. We also tested whether foraging behaviour differed among group types, between sex in adults, and between females of different reproductive status. At a fine scale, intake rate increased linearly with bite size and increased following a type II curvilinear function with biomass on feeding sites. Forage intake rate also increased linearly with plant quality. Male and female kiangs had similar intake rates. Likewise, gravid and lactating females had similar intake rates as barren and non-lactating females. At a coarse scale, kiangs spent longer time feeding in mesic than in xeric habitats, and spent more time feeding in early summer and fall than in late summer. Groups of adults with foals spent less time feeding than male groups and groups of adults without foals. Our findings suggest that kiangs use flexible foraging behaviours in relation to seasonal variations of vegetation quality and abundance, a likely outcome of the extreme seasonal conditions encountered on the Tibetan Plateau.     

Primiparous females do not exhibit reduced maternal care in gray seals (Halichoerus grypus)

We compared the behaviors of primiparous and multiparous gray seal (Halichoerus grypus) females over the course of lactation to examine whether poorly developed maternal behaviors may play a role in the reduced lactation performance observed in primiparous females. Overall, primiparous females spent as much time interacting with their pups as multiparous females. The proportion of time spent nursing their pup increased significantly between early and peak lactation in both primiparous and multiparous females. Although there was no significant difference in the duration of nursing bouts as a function of reproductive status, primiparous females nursed significantly more frequently (bouts/hour) and, therefore, spent a significantly greater proportion of time nursing than multiparous females throughout lactation. Primiparous gray seal females were also significantly more active than multiparous females, however, the difference in activity represented only a small proportion of the overall time budget. We conclude that poorly developed maternal behaviors resulting from a lack of prior reproductive experience are unlikely to account for lower levels of milk energy transfer to pups in primiparous gray seals.     

Reproductive energetics of the nectar-feeding bat<Emphasis Type="Italic"> Glossophaga soricina</Emphasis> (Phyllostomidae)

Pregnancy and lactation are energetically demanding periods for female mammals. Unique amongst mammals, bats have to allocate considerable amounts of energy into their offspring because juveniles cannot be weaned until they are capable of flying at almost adult size. Similar to other bat species, female nectar-feeding bats should increase their energy intake after parturition to meet the energy demands of offspring growth. However, previous studies have shown that nectar-feeding bats differ from other similar-sized bats in having a much higher metabolic rate. Therefore, I examined how nectarivorous bats respond to the energetic challenge of reproduction. In this study, the daily energy intake of pregnant and lactating Glossophaga soricina was measured during a 6-week period prior to and a 10-week period after parturition. Body mass of G. soricina increased linearly until parturition. Within the same time period, daily flight time decreased and daily energy intake remained constant. Probably, the reduced flight activity of pregnant bats compensated for the increased power requirements of flight, thus resulting in an almost constant daily energy turnover. During 35 days after parturition, neither flight time, body mass nor daily energy intake of lactating females changed significantly. On average, the daily energy intake of pregnant, lactating or non-reproducing G. soricina was not significantly different. Possibly, for unknown reasons, female G. soricina maintain a daily energy intake of a constant high level during and beyond reproduction.     

Seasonal, sex, and interspecific differences in activity time budgets and diets of patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus), living sympatrically in northern Cameroon

I examined seasonal, sex, and interspecific differences in activity time budgest and diets of patas (Erythrocebus patas) and sympatric tantalus monkeys (Cercopithecus aethiops tantalus) on the basis of 5-day data sets collected in three and two different seasons, respectively, by the method of focal animal sampling. The seasons included species-specific mating and birth seasons. As compared with not only the birth season but also conspecific females, both patas resident male and tantalus male spent less time feeding and more time resting, day and night, in their respective mating seasons. Given that day-resting time includes time for vigilance for non-resident males and receptive females, this may reflect that males should minimize time spent feeding to allow maximum participation in other fitness-increasing activities such as mating-relating activities asSchoener (1971) predicted. In both species, the males consumed fruits containing less protein but more calories and showed a high feeding rate to compensate for the shorter time spent feeding in the mating season. In contrast, females consumed protein-rich food types (i.e. animals, protein-rich seeds, leaves, and flowers) in the birth season to meet the high demand for protein due to pregnancy and lactation. Given that the season for males was considered to be not a calendar but a reproductive “season” (i.e. mating or birth season), both sexes of patas spent more time moving and less time day- and night-resting than did the tantalus counterparts irrespective of the “season”. Patas subsisted on fruits, gums, and supplementarily lipid-rich seeds as an energy source and animal matters and protein-rich seeds as a protein source. In contrast, tantalus subsisted on fruits and lipid-rich seeds as energy and flowers and leaves as protein.     

Effects of age,lactation, and repeated cycles on rhesus monkey copulatory intervals

Young, sexually mature female rhesus monkeys copulate on more days prior to conception than do older females, and this prolonged discrete mating period is associated with an earlier rise in serum estradiol prior to the first ovulation of the breeding season. The influence of repeated ovulatory cycles and the presence of a suckling infant on the copulatory patterns were examined in two separate analyses. Extending previous work, young, nulliparous females copulated on more days at the first ovulation of the breeding season than did older, multiparous females. However, the duration of the copulatory period at the second ovulation of the breeding season was similar and significantly shorter for both age groups. Furthermore, the presence of a suckling infant did not influence the duration of the mating periods in adult, multiparous females. The onset of copulatory behavior for all females was associated with serum estradiol concentrations of approximately 90 pg/ml, indicating that the age and cycle differences in the duration of the copulatory periods are due to the time course of serum estradiol prior to ovulation. A separate, longitudinal analysis of the duration of the mating period associated with the first ovulation of three successive breeding seasons indicated that females copulated on more days during their first ovulatory cycle of their first breeding season. These data indicate that the copulatory interval is longer for females during the first ovulation of the breeding season, and this pattern is accentuated in young, sexually mature animals.     

Age, social rank and lactational status influence ovulatory patterns in seasonally breeding rhesus monkeys

Rhesus monkeys housed outdoors exhibit a distinct breeding season limited to the fall and winter months. Four groups of female rhesus monkeys, multiparous nonlactating (MNL; n = 8), multiparous lactating (ML; n = 6), primiparous lactating (PL; n = 3) and nulliparous first-time ovulators (N; n = 6) were studied to investigate the influence of age, parity, and social dominance rank on the parameters of the breeding season. MNL exhibited the longest season (146 days), and PL the shortest (70 days), with N (106 days) and ML (89 days) intermediate. PL females also had a significantly reduced percentage of normal ovulations compared to other groups. Neither body weight nor estimates of body fat were related to either the timing of the ovulatory season or the quality of ovulations within the season. Parity and social dominance rank were significantly related to the percentage of normal ovulations (r = 0.85), with low-ranking, primiparous females exhibiting the fewest normal ovulations. These data indicate that the presence of a suckling infant acts synergistically with environmental factors to determine the parameters of the breeding season. Furthermore, postpubertal females may be more responsive to those factors that terminate the breeding season, and some factor independent of body weight but associated with low social dominance rank and/or primiparity renders females less capable of normal luteal function during the breeding season.     

Fecal cortisol levels in free-ranging female chacma baboons: relationship to dominance, reproductive state and environmental factors

Savannah baboons are one of the few mammalian species that do not exhibit seasonal reproduction patterns and are therefore ideally suited to study the effect of female reproductive states (cycling, pregnant, lactating) on cortisol levels independent of seasonal factors. Fecal samples from 10 free-ranging female chacma baboons (Papio hamadryas ursinus), collected during a period of 17 months, were analyzed using a steroid-extraction method. Reproductive state had a significant effect on fecal cortisol, with lowest levels found in estrous females. Fertility was not related to fecal cortisol levels; we found no significant differences between samples collected on conceptive and nonconceptive cycles. Environmental factors explained most of the variance of fecal cortisol levels. Cortisol measures were strongly correlated with seasonal differences such as daylight duration, temperature and the amount of time that baboons spent resting. We measured higher cortisol levels during winter months and suggest that this could be related to shorter resting periods and to the cold minimum ambient temperatures at this study site. Finally, we found no relationship between social rank nor the rate of agonistic interactions with basal fecal cortisol levels.