Non-lactating Females Research Articles

Effects of early horn growth on reproduction and hunting mortality in female chamois

1. Environmental conditions during early development can affect the growth patterns of vertebrates, influencing future survival and reproduction. In long-lived mammals, females that experience poor environmental conditions early in life may delay primiparity. In female bovids, annual horn growth increments may provide a record of age-specific reproduction and body growth. Horn length, however, may also be a criterion used by hunters in selecting animals to harvest, possibly leading to artificial selection. 2. We studied three populations of chamois (Rupicapra rupicapra) in the western Alps to explore the relationships between female horn length and early growth, age of primiparity and age-specific reproduction. We also compared the risk of harvest to reproductive status and horn length. 3. Early horn growth was positively correlated with body mass in pre-reproductive females and with reproduction in very young and senescent adults. Females with strong early horn growth attained primiparity at an earlier age than those with weak early growth. Horn length did not affect hunter selection, but we found a strong hunter preference for nonlactating females. 4. Our research highlights the persistent effects of early development on reproductive performance in mammals. Moderate sport harvests are unlikely to affect the evolution of phenotypic traits and reproductive strategies in female chamois. A policy of penalizing hunters that harvest lactating females, however, may increase the harvest of 2-year-old females, which have high reproductive potential.

Non-lactating versus lactating females: a comparison of sex steroids, sexual coloration, and sexual behavior in Japanese macaques

Female Japanese macaques are seasonal breeders distinguished by their red-colored hindquarters, face, and nipple skin areas. Intensity of coloration seems to be associated with sexual attractiveness, behavior, and fluctuating sex steroids. Our aim was to investigate whether the color intensity of these regions differed between lactating (LA) and non-lactating (NLA) females during sexually inactive (SI) and active (SA) phases. Coloration scores of 19 adult females were classified using color tables. Estrogen and progesterone metabolites were determined in fecal samples. Weekly comparison between both groups revealed significantly increased coloration of the hindquarters area from week 13 (SI) until the end of the observation period, and for the nipple skin throughout the SI and SA periods. Face coloration differed marginally. Hormonally, NLA females showed significantly increased excretion rates of sex steroids at the end of the SI phase and throughout the whole SA period. Logistic regression analyses between elevated fecal steroids and nipple coloration disclosed a significant relationship for NLA females during the SI period. This connection persisted and included hindquarter coloration during the SA period. NLA females showed increased intromission with ejaculation, but no difference was found for intromission without ejaculation. In conclusion, results demonstrate increased endocrine excretion rates for NLA females during the whole observation period, paralleled by an enhanced, fertility-signaling sexual attractiveness.

Serum corticosteroid binding globulin expression is modulated by fasting in polar bears ( Ursus maritimus)

Polar bears ( Ursus maritimus) from several subpopulations undergo extended fasting during the ice-free season. However, the animals appear to conserve protein despite the prolonged fasting, though the mechanisms involved are poorly understood. We hypothesized that elevated concentrations of corticosteroid binding globulin (CBG), the primary cortisol binding protein in circulation, lead to cortisol resistance and provide a mechanism for protein conservation during extended fasting. The metabolic state (feeding vs. fasting) of 16 field sampled male polar bears was determined based on their serum urea to creatinine ratio (> 25 for feeding vs. < 5 for fasting). There were no significant differences in serum cortisol levels between all male and female polar bears sampled. Serum CBG expression was greater in lactating females relative to non-lactating females and males. CBG expression was significantly higher in fasting males when compared to non-fasting males. This leads us to suggest that CBG expression may serve as a mechanism to conserve protein during extended fasting in polar bears by reducing systemic free cortisol concentrations. This was further supported by a lower serum glucose concentration in the fasting bears. As well, a lack of an enhanced adrenocortical response to acute capture stress supports our hypothesis that chronic hunger is not a stressor in this species. Overall, our results suggest that elevated serum CBG expression may be an important adaptation to spare proteins by limiting cortisol bioavailability during extended fasting in polar bears.

Survival and Breeding Transitions for a Reintroduced Bison Population: a Multistate Approach

The iconic plains bison (Bison bison) have been reintroduced to many places in their former range, but there are few scientific data evaluating the success of these reintroductions or guiding the continued management of these populations. Relying on mark–recapture data, we used a multistate model to estimate bison survival and breeding transition probabilities while controlling for the recapture process. We tested hypotheses in these demographic parameters associated with age, sex, reproductive state, and environmental variables. We also estimated biological process variation in survival and breeding transition probabilities by factoring out sampling variation. The recapture rate of females and calves was high (0.78 ± 0.15 [SE]) and much lower for males (0.41 ± 0.23), especially older males (0.17 ± 0.15). We found that overall bison survival was high (>0.8) and that males (0.80 ± 0.13) survived at lower rates than females (0.94 ± 0.04), but as females aged survival declined (0.89 ± 0.05 for F ≥15 yr old). Lactating and non-lactating females survived at similar rates. We found that females can conceive early (approx. 1.5 yr of age) and had a high probability (approx. 0.8) of breeding in consecutive years, until age 13.5 years, when females that were non-lactating tended to stay in that state. Our results suggest senescence in reproduction and survival for females. We found little support for the effect of climatic covariates on demographic rates, perhaps because the park's current population management goals were predicated from drought-year conditions. This reintroduction has been successful, but continued culling actions will need to be employed and an adaptive management approach is warranted. Our demographic approach can be applied to other heavily managed large-ungulate systems with few or no natural predators.

Hematology of Southern Beaufort Sea Polar Bears (2005–2007): Biomarker for an Arctic Ecosystem Health Sentinel

Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.

EFFECT OF DIVERGENT SELECTION FOR UTERINE CAPACITY ON PROGESTERONE, ESTRADIOL AND CHOLESTEROL LEVELS AROUND IMPLANTATION TIME IN RABBITS.

The effects of selection for high (H) and low (L) uterine capacity on serum and uterine fluid levels of progesterone and serum levels of estradiol and cholesterol, near implantation (day 6 of gestation), were studied. Both lines had similar ovulation rates (15.2 vs 14.4), but different number of embryos (12.8 vs 11.0; P&lt;0.05) for H and L, respectively. Progesterone, cholesterol and estradiol were similar in both lines (9.3 and 9.6 ng/ml serum progesterone; 15.6 and 13. 7 ng/ml of uterine fluid progesterone; 28.1 and 27.6 pg/ml of estradiol; and 66.6 and 68.0 mg/dl of cholesterol for H and L, respectively). Lactation strongly affected the variables studied. Lactating does had higher ovulation rates than non-lactating (15.6 vs 14.0; P&lt;0.05), but no differences were detected for the number of embryos recovered (12.2 and 11.6 for lactating and non-lactating, respectively) or for embryo survival (0. 79 and 0.84 for lactating and non-lactating). L does had lower levels of serum progesterone (8.7 ng/ml), uterine fluid progesterone (13.0 ng/ml) and serum cholesterol (59.3 mg/dl) than non-lactating females (10.2 ng/ml, 16.3 ng/ml and 75.3 mg/dl respectively; P&lt;0.05). Lactation did not affect serum levels of estradiol. Serum progesterone levels were slightly correlated with ovulation rate (r=0.24; P&lt;0.05). Ovulation rate and number of embryos recovered were correlated with progesterone uterine fluid in lactating females (r=0.55 and 0.49 respectively; P&lt;0.05). Embryo survival in lactating females was negatively correlated with the concentration of estradiol (r=-0.39; P&lt;0.05).

Embryo transfer technique: Factors affecting the viability of the corpus luteum in llamas

The aim of the present study was to evaluate the effect of the embryo transfer (ET) maneuvers on plasma progesterone concentrations in recipient Lama glama females and the relationship between the site the embryo was transferred to and corpus luteum (CL) localization. Experiment I (effect of transcervical threading): adult non-pregnant, non-lactating llama females were randomly assigned into two groups: control group (without cervical threading, n = 10) and group A (with cervical threading, n = 10). In both groups, CL activity was evaluated through measurement of progesterone plasma concentrations. In group A, on Day 6 after inducing ovulation with buserelin, the cervix was threaded to evaluate the effect of the maneuver on CL viability. No significant differences were observed in mean progesterone concentrations between groups ( P > 0.05). Experiment II (effect of depositing PBS): females ( n = 66) were randomly assigned into six groups ( n = 10 per group and control group: n = 6) to evaluate the effect of depositing PBS in different sites in the uterus in relation to the localization of the CL: group ‘Left-Ipsilateral’: transcervical placing of PBS in the left uterine horn (CL in left ovary); group ‘Left-Contralateral’: transcervical placing of PBS in the left uterine horn (CL in right ovary); group ‘Right-Ipsilateral’: transcervical placing of PBS in the right uterine horn (CL in right ovary); group ‘Body-Left’: transcervical placing of PBS in the uterine body (CL in left ovary); group ‘Body-Right’: transcervical placing of PBS in the uterine body (CL in right ovary) and control group. Corpus luteum activity was evaluated in all groups by measuring plasma progesterone concentrations. On Day 6 post-buserelin, the corresponding maneuver was carried out according to the group. No significant differences were found for the mean plasma progesterone concentrations between groups ( P > 0.05). Experiment III (effect of ET on CL viability): females ( n = 22) were used as embryo donors and 50 females as recipients, in order to evaluate if placing the embryo in different areas of the uterus influences CL viability. Recipients were randomly divided into five groups, according to the place in the uterus where the ET was conducted with respect to the ovary where ovulation occurred: group ‘Left-Ipsilateral’: ET in the left uterine horn (CL in left ovary); group ‘Left-Contralateral’: ET in the left uterine horn (CL in right ovary); group ‘Right-Ipsilateral’: ET in the right uterine horn (CL in right ovary); group ‘Body-Left’: ET in the uterine body (CL in left ovary) and group ‘Body-Right’: ET in the uterine body (CL in right ovary). Corpus luteum activity was evaluated in all groups by measuring plasma progesterone concentrations. Embryos were recovered by flushing the uterus on Day 8 after the first mating of the donor and transcervical ET was carried out in recipients 6 days after buserelin administration. Pregnancy rates were: group ‘Left-Ipsilateral’: 50%; group ‘Left-Contralateral’: 20%; group ‘Right-Ipsilateral’: 30%; group ‘Body-Left’ and ‘Body-Right’: 10%. No significant differences ( P = 0.4728) were detected between the pregnancy rates in the five groups. Threading the cervix and transcervical placing of PBS either in the uterine horns or the body did not affect plasma progesterone concentrations in the llama, indicating that the different embryo transfer maneuvers do not interfere with CL viability. To improve pregnancy rates it could be suggested that ET in the left uterine horn with an ipsilateral CL, is the most desirable option.

Effects of chronic and intermittent cocaine treatment on dominance, aggression, and oxytocin levels in post-lactational rats

Little is known about mechanisms underlying female rodent aggression during the late postpartum period with no pups present. Studies of aggression, dominance, and oxytocin (OT) response in cocaine-treated females are sparse. This study was designed to examine dominance (drinking success) and aggression in a limited-access drinking model of water competition. Acute OT level measures were made on postpartum day (PPD) 36 in several brain regions of interest. Chronic and intermittent cocaine- and saline-treated and untreated rats 10 days post-weaning were tested (without pups) over PPDs 31-35 following cessation of cocaine treatment 10-30 days before testing. Subjects were water-deprived overnight, and triads consisting of an untreated control (UN), a chronic continuous saline-treated (CS), and chronic continuous cocaine-treated (CC; 30 mg/kg/day throughout gestation) or a UN, an intermittent saline-treated (IS), and an intermittent cocaine-treated (IC; 30 mg/kg two consecutive days every 4 days throughout gestation until PPD 20) female were tested for aggression and drinking behavior during 5 min sessions on five consecutive days. The amygdala, medial preoptic area (MPOA), and ventral tegmental area were assayed for OT levels. CC and IC females were more aggressive than controls, but only IC females drank more often than controls. OT levels were lower in the MPOA of IC and CC females than in controls. Findings demonstrate that long after cessation of treatment, CC- and IC-treated non-lactating females (no pups present) had higher rates of aggression, altered drinking behavior, and acutely lower MPOA OT levels.

Age-related multi-year associations in female humpback whales (Megaptera novaeangliae)

Analyses of social structures in baleen whales are rare, and so far, they are thought to consist of mostly short and unstable associations. We investigated the association patterns of individual humpback whales from a summer feeding aggregation in the Gulf of St. Lawrence from 1997 to 2005. Photo-identified animals were sexed using genetic methods and were grouped into five categories: juvenile males/females, mature males and lactating/non-lactating females. We calculated half-weight association indices within and between the groups and found that 45% of the observation showed single animals and another 45% small groups (two to three) consisting mainly of mature animals besides lactating females. Using permutation tests, we found evidence for long-term associations between mature males and non-lactating females as well as among non-lactating females. Standardised lagged association rates revealed that these male-female groups disassociated quickly over about 2 weeks, whereas associations increased again towards the beginning of the breeding season. Non-lactating females of similar age engaged in multi-seasonal stable pairs for up to six consecutive feeding seasons; no mature male-female association was observed in consecutive years. The females with the most stable and long-term associations also had the highest reproductive output. While the risk of predation could not explain these long-term bonds, feeding cooperation seemed the most plausible explanation for group forming behaviour during the summer months.

Winter body temperature patterns in free-ranging Cape ground squirrel, Xerus inauris: no evidence for torpor

The body temperature (T(b)) of Cape ground squirrels (Xerus inauris, Sciuridae) living in their natural environment during winter has not yet been investigated. In this study we measured abdominal T(b) of eight free-ranging Cape ground squirrels over 27 consecutive days during the austral winter. Mean daily T(b) was relatively stable at 37.0 ± 0.2°C (range 33.4 to 40.2°C) despite a marked variation in globe temperature (T(g)) (range -7 to 37°C). Lactating females (n = 2) consistently had a significantly higher mean T (b) (0.7°C) than non-lactating females (n = 3) and males. There was a pronounced nychthemeral rhythm with a mean active phase T(b) of 38.1 ± 0.1°C and a mean inactive phase T(b) of 36.3 ± 0.3°C for non-lactating individuals. Mean daily amplitude of T(b) rhythm was 3.8 ± 0.2°C. T(b) during the active phase closely followed T(g) and mean active phase T(b) was significantly correlated with mean active phase T(g) (r(2) = 0.3-0.9; P < 0.01). There was no evidence for daily torpor or pronounced hypothermia during the inactive phase, and mean minimum inactive phase T(b) was 35.7 ± 0.3°C for non-lactating individuals. Several alternatives (including nocturnal huddling, an aseasonal breeding pattern and abundant winter food resources) as to why Cape ground squirrels do not employ nocturnal hypothermia are discussed.

Behavioural reactions of wintering humpback whales (Megaptera novaeangliae) to biopsy sampling in the western South Atlantic

Molecular analysis has become a powerful tool in cetacean ecology since it supports efficient conservation policies. Remote biopsy sampling is the most efficient method to obtain epithelial material for analysis purposes; however, as an intrusive technique it presents inherent costs, evidenced by behavioural reactions. Clarifying which factors influence these responses is essential to assess its impact and prevent possible long-term effects. For eleven winters, samples from humpback whales were collected in the Abrolhos Bank, the main breeding ground of this species in the western South Atlantic. We analysed the influence of several characteristics of the shot, vessels, groups and behaviour on the frequency and intensity of the whales' response. The majority of biopsied whales did not show any detectable response. Among those that responded, a low-level category of reaction was most frequent. The use of larger boats resulted in less intense responses. Responses were influenced by group size and behavioural state: large groups, which were involved in aggressive mating behaviour, reacted less frequently than smaller groups. Females with calves showed less intense reactions than non-lactating females. The behaviour of the animals prior to and during the boat approach also affected their response: resting whales responded more intensely than whales involved in social or travel activities. Comparison with previous studies confirmed that reactions vary in intensity according to location: whales biopsied in feeding grounds responded with more intensity than those in breeding grounds, which in turn responded more intensely than whales in migration. This study reinforces existing evidence that biopsy sampling is unlikely to have long-term effects and can thus continue to be used as one of the main tools to access information which is vital for conservation.

Effect of estradiol benzoate used at the start of a progestagen treatment on superovulatory response and embryo yield in lactating and non-lactating llamas

Two experiments were conducted to determine the effect of estradiol benzoate (EB) and intravaginal progestagen treatment on ovarian follicular dynamics and superstimulatory response in eCG-treated llamas. The purpose of Experiment 1 was to evaluate the effect of EB and progestagen treatment starting at different phases of dominant follicle (DF1) development on regression pattern and subsequent follicle wave emergence (WE2) in lactating and non-lactating llamas. Early lactating ( n = 24, 30 ± 4 days postpartum) and non-lactating ( n = 24) females were assigned in equal numbers ( n = 8) to one of three groups according to the phase of DF1 (growing, static or regressing) determined by ultrasonography from day −3 to day 0. At day 0, llamas received an intravaginal sponge (MPA, 150 mg) and 5 mg of MPA (i.m.). Half of the females ( n = 4) of each group were injected with 2 mg (i.m.) of EB and half were not (control group). A 2 × 2 × 3 (lactational status, EB treatment and follicular phases) factorial design was used. Each sponge was removed 8 days later. Ovaries were monitored from day 0 to day 12. Daily blood samples were taken to determine 17β-estradiol (E 2) profiles from day 0 to day 8. The DF1 regression pattern was not affected ( P > 0.05) by the phase of follicle wave at the start of the treatment or any interactions among main effects. Follicle wave emergence in EB-treated llamas was delayed ( P < 0.05) by 2.3 days compared with non-treated llamas. Following EB treatment, plasma concentrations of E 2 were greater ( P < 0.05) from day 1 to day 5 in the treated than in non-treated females, but not from day 6 onward ( P > 0.05). Experiment 2 was designed to evaluate the effect of this treatment on the ovarian superovulatory response and embryo yield following eCG treatment administered on day of follicular wave emergence as determined in the Experiment 1. The same lactating ( n = 18, 61 ± 4 days postpartum) and non-lactating ( n = 18) llamas at random stages of follicle wave were treated as those in Experiment 1 and received 1200 IU of eCG at the time of WE2 (EB-treated = day 6.5 and non-treated = day 4.5). Llamas were mated 5 days after sponge withdrawal. A second mating was allowed 24 h later. Embryos were collected between 7 and 8 days after the first mating and blood samples were taken to determine progesterone (P 4) concentrations. The mean number of follicles on day of mating and the number of CL on day of embryo collection were not affected by lactational status, EB treatment or their interactions ( P > 0.05). Ovulation rate and mean (±SEM) number of recovered embryos for EB treatment group (67.5% and 2.4 ± 0.4) were greater ( P < 0.05) than for no EB treatment (51.1% and 1.1 ± 0.4). Plasma P 4 concentrations and number of CL per llama were correlated ( r = 0.49; P = 0.014). In conclusion, progestagen plus EB treatment facilitates the prediction of the emergence of a new follicular wave approximately 6 days after treatment and resulted in a higher ovulation rate and embryo production in ovarian superstimulated llamas regardless of lactational status.

Self-grooming induced by sexual chemical signals in male root voles (Microtus oeconomus Pallas)

Sniffing is one-way animals collect chemical signals, and many males self-groom when they encounter the odor of opposite-sex conspecifics. We tested the hypothesis that sexual chemical signals from females can induce self-grooming behavior in male root voles (Microtus oeconomus Pallas). Specifically, we investigated the sniffing pattern of male root voles in response to odors from the head, trunk, and tail areas of lactating and non-lactating females. The self-grooming behavior of males in response to female individual odorant stimuli was documented, and the relationship between self-grooming and sniffing of odors from the head, trunk, and tails areas were analyzed. Sniffing pattern results showed that males are most interested in odors from the head area, and more interested in odors from the tail as compared to the trunk area. Males displayed different sniffing and self-grooming behaviors when they were exposed to odors from lactating females as compared to non-lactating females. Males also spent more time sniffing and engaged in more sniffing behaviors in response to odors from the lactating females' tail area as compared to the same odors from non-lactating females. Similarly, males spent more time self-grooming and engaged in more self-grooming behaviors in the presence of individual odors from lactating females as compared to individual odors from non-lactating females. Partial correlation analyses revealed that the frequency of self-grooming was significantly correlated with the frequency of tail area sniffs. Results from this experiment suggest that sexual attractiveness of lactating females is stronger than that of non-lactating females. Furthermore, the partial correlation analysis demonstrated that self-grooming in males is induced by odors from the tail area of females. Collectively, these results support the hypothesis that sexual chemical signals from females can induce self-grooming behavior in male root voles. Self-grooming may also reflect the groomer's sexual motivation and facilitate sexual interactions.

Effects of age on cerebrospinal fluid oxytocin levels in free-ranging adult female and infant rhesus macaques.

There is growing interest in examining oxytocin and social functioning in human and non-human primates. Studies of human oxytocin biology are typically restricted to peripheral assessments because opportunities to collect cerebrospinal fluid (CSF) are rare. Several studies have examined CSF oxytocin levels in captive adult primates, but none to our knowledge have been conducted under free-ranging conditions and inclusive of infants. The main goal of this study was to establish feasibility of quantifying CSF oxytocin levels in free-ranging adult female and infant rhesus monkeys living on Cayo Santiago, PR. CSF oxytocin levels were examined in relation to individuals' demographic and reproductive characteristics as well as plasma cortisol levels. CSF oxytocin concentrations ranged from 36.02 to 134.41 pg/ml in adult females (ages 7-26 years; N = 31) and 35.94 to 77.3 pg/ml in infants (ages 38-134 days; N = 17). CSF oxytocin levels were positively correlated with adult female age and negatively correlated with infant age. The former correlation was driven by reproductive status. CSF oxytocin levels were unrelated to dominance rank or plasma cortisol levels. In contrast to a previous study of plasma oxytocin concentrations in this population, CSF oxytocin levels did not differ significantly between lactating and non-lactating females. These findings: 1) provide feasibility data for examining CSF oxytocin levels in free-ranging non-human primates and 2) indicate that CSF oxytocin levels may be a biomarker of age-related central nervous system changes across lifespan development. Research is now required to examine CSF oxytocin levels in the context of social functioning in free-ranging rhesus monkeys.

Consequences of Exposure to Leprosy in a Population of Wild Nine-banded Armadillos

Nine-banded armadillos (Dasypus novemcinctus) are the only free-ranging vertebrates other than humans known to exhibit naturally occurring infections of Mycobacterium leprae, the causative agent of leprosy, but little is known about ecological consequences of leprosy in wild populations. We studied a population of armadillos in western Mississippi during the summers of 2007 and 2008. Consistent with previous work, we found no evidence of leprosy in juveniles or yearlings, suggesting no vertical transmission of disease. In 2008, a higher proportion of adult females were leprosy-positive than were adult males. Across both years, leprous females were significantly larger than nonleprous females, but a higher proportion of leprous females were lactating and lactating females were larger than nonlactating females. The behavior of leprosy-positive and leprosy-negative animals did not differ. Leprosy-positive individuals tended to be spatially clumped, but these results were not statistically significant. Our findings suggest leprosy had minimal impacts on individuals in this population of armadillos, which is a surprising and unexpected result given the substantial costs of infection documented in the laboratory.

Seasonality, sociality, and reproduction: Long-term stressors of ring-tailed lemurs ( Lemur catta)

Fecal glucocorticoid (fGC) concentrations are reliable, non-invasive indices of physiological stress that provide insight into an animal's energetic and social demands. To better characterize the long-term stressors in adult members of a female-dominant, seasonally breeding species – the ring-tailed lemur ( Lemur catta) – we first validated fecal samples against serum samples and then examined the relationship between fGC concentrations and seasonal, social, demographic, genetic, and reproductive variables. Between 1999 and 2006, we collected 1386 fecal samples from 32 adult, semi-free-ranging animals of both sexes. In males and non-pregnant, non-lactating females, fGC concentrations were significantly elevated during the breeding season, specifically during periods surrounding known conceptions. Moreover, group composition (e.g., multi-male versus one-male) significantly predicted the fGC concentrations of males and females in all reproductive states. In particular, the social instability introduced by intra-male competition likely created a stressor for all animals. We found no relationship, however, between fGC and the sex, age, or heterozygosity of animals. In reproducing females, fGC concentrations were significantly greater during lactation than during the pre-breeding period. During pregnancy, fGC concentrations were elevated in mid-ranking dams, relative to dominant or subordinate dams, and significantly greater during the third trimester than during the first or second trimesters. Thus, in the absence of nutritional stressors, social dominance was a relatively poor predictor of fGC in this female-dominant species. Instead, the animals were maximally challenged by their social circumstances and reproductive events—males by competition for mating opportunities and females by late-term gestation and lactation.

A preliminary assessment of the impact of disturbance and handling on Weddell seals of McMurdo Sound, Antarctica

There has been growing concern over the impact of increased human disturbance and research effects on Antarctic species. The Weddell seal of McMurdo Sound in particular has been used as a model species for over four decades of research, with some individuals handled multiple times over a single season. Using opportunistic data, we performed an assessment of blood indicators in adult males (n = 26) and adult females (n = 24) based on high versus low disturbance areas, with results showing no variation in overall seal health. In addition, we performed a preliminary analysis of blood and faecal indicators of inflammation and stress collected from adult, non-lactating females (n = 13) handled twice in less than two weeks for research purposes. There was no indication of a change in white blood cells, platelets, globulins or haptoglobins, or faecal corticosteroids (all P &gt; 0.05). While based on a small, opportunistic sample size with limited power in some cases, preliminary results indicate there is no acute impact of repeated handling or difference in overall traffic level on adult Weddell seals.

Olfactory guidance of nipple attachment and suckling in kittens of the domestic cat: Inborn and learned responses

In 60 kittens (11 litters) from free-ranging domestic cats we investigated the role of chemical cues in facilitating nipple attachment and suckling during the first month of postnatal life when kittens are totally dependent on the mother's milk. Kittens were tested both together and individually on sedated females in different reproductive states. We found (1) that newborn kittens with no suckling experience responded to the ventrum of lactating but not to the ventrum of nonlactating females with search behavior and attached to nipples within minutes; (2) that even in older kittens, nipple attachment depended on females' reproductive state, with virtually no attachments on nonreproducing females, some on pregnant females, the greatest number on early-lactating females, followed by a decline on late-lactating females; and (3) that kittens could locate their particular, most used nipple on their mother but not on a female of similar lactational age, even after eye opening. We suggest that kittens respond from birth with efficient nipple-search behavior to inborn olfactory cues on the mother's ventrum, that emission of these is under hormonal control, but that kittens also quickly learn olfactory cues specific to their own mother and to their own particular nipples.

Unusual presentation and inconlusive biopsy render fibroadenoma in two young females a diagnostic dilemma

Two young non-lactating females presented with acutely painful breast masses. Sonographic features showed mixed echogenic masses. Core biopsy was non-diagnostic in both and surgical excision revealed infarcted fibroadenomas.&#x0D; &#x0D; Although fibroadenomas are common, they do not commonly infarct and only rarely in non-lactating and non-pregnant females. &#x0D; &#x0D; These two cases highlight the clinical and imaging characteristics of this important differential diagnosis.

Foraging decisions in a capital breeder: trade-offs between mass gain and lactation

The high energetic costs of lactation can lead to fundamental trade-offs in life-history traits, particularly in young females that reproduce before completing body growth. We assessed whether lactating female mountain goats (Oreamnos americanus) used behavioural tactics at fine spatio-temporal scales to increase energy intake to compensate for the costs of lactation. Lactating females increased bite rate and chewing rate compared with non-lactating females, but selected similar foraging sites in terms of plant quality and abundance. At peak lactation, forage intake of lactating females was >40% greater than that of non-lactating females. For females that had reached asymptotic body mass (i.e. > or =6 years old), summer mass gain of lactating females was similar to that of non-lactating females. At 4 and 5 years of age, however, daily mass gain of lactating females was about 20% lower than that of non-lactating females. We conclude that increased foraging may allow fully-grown lactating females to compensate for the energetic costs of lactation, but that there is a major trade-off between mass gain and lactation for younger females.