Pregnancy and the reproductive cycle were monitored in 13 captive southern white rhinoceros (Ceratotherium simum simum) by measuring progesterone metabolites in fecal extracts and by observing behavior patterns. Fecal hormones were measured using a monoclonal antibody produced against 4-pregnen-11-o1-3,20-dione hemisuccinate:BSA. Several subjects exhibited flat or erratic endocrine profiles, but we found evidence for 17 reproductive cycles in five females. Mating behavior coincided with nadirs in pregnane concentrations. These cycles appeared to fall into two general categories: those of approximately 1 month in duration (Type I: X -± SEM = 35.4 ± 2.2 days; n = 10) and those lasting approximately 2 months (Type II: 65.9 ± 2.4 days; n = 7). Interluteal phase lengths were similar for the two cycle types, but Type II cycles were characterized by extended luteal phases lasting more than twice as long as Type I luteal phases. Because Type I cycles predominated in our data and because evidence suggests that some Type II cycles may be aberrant, we argue that these approximately monthly cycles represent the typical reproductive cycle for this species. Three females became pregnant during the course of the study. We were able to detect pregnancy by approximately 3 months post-breeding, as indicated by sustained pregnane concentrations markedly higher than nonpregnant luteal phase concentrations. These data help to characterize important reproductive events of this species and should be useful for captive breeding efforts for this threatened species.

No abstract

SUMMARYCirculating concentrations of testosterone and its precursor androstenedione, as well as dehydroepiandrosterone (DHEA) and the adrenal hormones cortisol and corticosterone were measured at monthly intervals in 14 male killer whales (Orcinus orca) aged 0.8-38 years. Analyses were performed for examination of the relationships of age, sexual maturation status (STATUS), season, and environmental temperature (monthly air ambient temperature, A-TEMP) with hormone production using a mixed effects linear regression model with animal ID as the random variable. Hormone profiles, derived from enzyme immunoassay procedures validated herein, established that simultaneous up-regulation of androstenedione and testosterone production occurs at puberty, when males are aged 8-12 years. Androgen (testosterone and androstenedione) production in pubertal and adult males was influenced by season, with highest (p < 0.01) concentrations observed in spring and summer months. A significant effect of STATUS and season on DHEA production was also documented, with higher (p < 0.05) concentrations in pubertal and adult males compared to juvenile males, and higher (p < 0.05) concentrations in the months of summer than the fall. Among adult males (≥13 years), those classified as aged (≥31 years) had concentrations of testosterone and both glucocorticoids that were lower (p < 0.05), and those of androstenedione that were higher (p < 0.05) than their younger counterparts. The cortisol:corticosterone ratio for adult males was 7 : 1, and both glucocorticoids were affected by STATUS (p < 0.05), but not season or A-TEMP. Results of this research enhance our understanding of reproductive and adrenocortical function in healthy male killer whales and provide baseline profiles of hormone production for use in the species' health assessment and conservation.

Pregnancy and the reproductive cycle were monitored in 13 captive southern white rhinoceros (Ceratotherium simum simum) by measuring progesterone metabolites in fecal extracts and by observing behavior patterns. Fecal hormones were measured using a monoclonal antibody produced against 4-pregnen-11-o1-3,20-dione hemisuccinate:BSA. Several subjects exhibited flat or erratic endocrine profiles, but we found evidence for 17 reproductive cycles in five females. Mating behavior coincided with nadirs in pregnane concentrations. These cycles appeared to fall into two general categories: those of approximately 1 month in duration (Type I: X -± SEM = 35.4 ± 2.2 days; n = 10) and those lasting approximately 2 months (Type II: 65.9 ± 2.4 days; n = 7). Interluteal phase lengths were similar for the two cycle types, but Type II cycles were characterized by extended luteal phases lasting more than twice as long as Type I luteal phases. Because Type I cycles predominated in our data and because evidence suggests that some Type II cycles may be aberrant, we argue that these approximately monthly cycles represent the typical reproductive cycle for this species. Three females became pregnant during the course of the study. We were able to detect pregnancy by approximately 3 months post-breeding, as indicated by sustained pregnane concentrations markedly higher than nonpregnant luteal phase concentrations. These data help to characterize important reproductive events of this species and should be useful for captive breeding efforts for this threatened species.

Aggression control is becoming an important component in the management of animals in captivity, but rigorous quantification of aggressive behavior has heretofore been lacking. This study was done to assess the ability of melengestrol acetate (MGA) given with feed (1.54 mg/kg) to control aggression in a bachelor group of fringe-eared oryx (Oryx gazella callotis). Systematic behavioral observations were conducted and fecal androgen content was measured for 42 and 90 days, respectively, before treatment, and during the 42 days of treatment. There was a significant reduction in concentrations of fecal androgen from 153 ± 6.0 to 95 ± 4.5 ng/g (T 66 = 7, P < 0.0001). This reduction in androgen excretion was apparent after the first week of treatment. There was measurable MGA excreted in the feces during treatment. Although treatment did not arrest all aggressive behaviors among animals, the decline in androgens and increase in MGA was accompanied by a significant reduction in several measures of agonistic behavior. Posturing, aggressive contact, pursuit, and submission occurred significantly less frequently after treatment, and there was also a reduction in fighting-intention movements. Thus, both ritualized and nonritualized aspects of aggression were affected. Reductions in hormones and aggressive behaviors coincided temporally, suggestive of a potential causal relationship. Consistent with this hypothesis is a strong positive correlation between fecal androgen and total aggressive acts. This effect was not the result of a single behavioral element but occurred across several categories of agonistic behavior. Zoo Biol 20:375-388, 2001. INTRODUCTIONIn male ungulates, it has been suggested that there is a causal link between aggressive behavior and androgens [Bouissou, 1983]. A synthetic progestogen, melengestrol acetate (MGA), originally developed as an orally active contraceptive [Kirk et al., 1962], has been reported to decrease aggression in three ungulate species. Silastic implants containing MGA reduced intraspecific aggression in bachelor herds of scimitar-horned oryx, Oryx dammah [Blumer et al., 1992]. Male muntjacs (Muntiacus reevesi) fed MGA had significantly decreased sperm numbers, and anecdotal reports of behavior indicated reduced aggression [Stover et al., 1987]. Orally administered MGA reduced aggression during the early rut in farmed fallow bucks (Dama dama) [Wilson et al., 2000]. None of these studies, however, systematically quantified aggression before and after MGA administration, leaving the question of efficacy unresolved.The fringe-eared oryx (Oryx gazella callotis), an east African subspecies of the gemsbok (Oryx gazella), is a horselike antelope that lives in the harsh arid environments of east Africa. This species has no particular breeding season. Most frequently, territorial males breed females in their postpartum estrus. Herds of bachelor males are seldom found [Price, 1986;Wacher, 1988]. In captivity, however, it is sometimes necessary to hold males in all-male groups. Elevated aggres...

Comparisons of circulating and excreted corticosteroid profiles during a biological stress response could provide more data concerning the timing and magnitude of acute hormone changes in different sample matrices. A stress test was performed in 13 zoo-based killer whales (Orcinus orca) whereby animals were elevated out of the water on a rising lift-bottom platform for 20 min. Paired blood and feces were tested for cortisol, corticosterone, aldosterone, and their metabolites and hematological and serum chemistry parameters. Circulating corticosteroids significantly increased during the stress test and returned to pre-treatment concentrations within 24 h, indicating hypothalamic-pituitary-adrenal-axis activation. Concentrations of fecal corticosteroid metabolites did not change significantly during the stress test. Significant differences between pre-test levels and the stress test stage were observed for counts of white blood cells and absolute neutrophils, consistent with a stress leukogram. For serum chemistry, significant deviations from baseline levels were seen for the majority (20/37) of measured parameters. This study provides a direct measurement of the physiologic response of clinically healthy killer whales to a stress event. However, due to the lack of significant changes in fecal hormone metabolite profiles, further investigation of the excretory dynamics of corticosteroids during acute and chronic stress is warranted.