Mammalian sociobiology and zoo breeding programs

Effects of Social Group Housing on the Behavioral and Physiological Responses of Captive Sub-Adult Giant Pandas

Wild giant pandas are inherently solitary creatures, however, the ex-situ conservation efforts significantly alter the living circumstances of their captive counterparts. Following the breeding period, giant pandas in captivity may be maintained in social groups. Currently, there is a lack of research on the effects of group housing on the physiology, behavior, and gut microbiota of captive giant pandas. This study divided six captive giant pandas into two groups following the breeding period. By comparing the behavior, physiology, and microorganisms of the two groups, we aim to investigate the behavioral responses and physiological adaptation mechanisms exhibited by captive giant pandas in a "group living" state. Our findings indicate that sub-adult giant pandas housed in group settings exhibit a significantly longer duration of playing behavior (including interactive and non-interactive play) compared to their counterparts housed separately (p < 0.001) while also demonstrating a significantly lower duration of stereotyped behavior than their separately housed counterparts. Additionally, an analysis of urine cortisol and heart rate variability between the two groups revealed no significant differences. Simultaneously, the group housing strategy markedly elevated the β diversity of gut microbiota in sub-adult giant pandas. In conclusion, the group-rearing model during the sub-adult stage has been shown to significantly alter the behavioral patterns of captive giant pandas. In conclusion, within the present captive setting, the group-rearing approach during the sub-adult stage proved to be less distressing for adult captive giant pandas.

Single- or Pair-Housed: Which Is Better for Captive Southern Tamanduas?

The captive environment can limit some important behavioral options for nonhuman animals, which often results in decreased welfare. The companion of a conspecific can be a source of complexity in captivity, but this aspect has received little attention for solitary species. This study investigated the effects of two different housing conditions on the behavior of a solitary species, the Southern tamandua (Tamandua tetradactyla). Six individuals housed singly and four housed in pairs in two Brazilian zoological institutions were observed for 10 days from 09:00h to 17:00h during the rainy season. Each individual was observed for 26:40 hours. Compared with singly housed tamanduas, paired animals were less inactive (single = 74.62 ± 5.2%, paired = 28.51 ± 0.04% of the records), foraged and explored more (single = 11.07 ± 3.0%, paired 31.48 ± 0.01% of the records), and exhibited a diversity of behaviors 102.56% greater than single tamanduas. These results suggest that interactions with conspecifics in captivity, even for solitary animals, can promote the performance of desirable behaviors, which in several species has been correlated with improved welfare.

Influence of dominance status on adrenal activity and ovarian cyclicity status in captive African elephants

The North American African (Loxodonta africana) elephant population is not self-sustaining, in part because of a high rate of abnormal ovarian activity. About 12% of adult females exhibit irregular cycles and 31% do not cycle at all. Our earlier work revealed a relationship between dominance status and ovarian acyclicity, with dominant females being more likely to not cycle normally. One theory is that dominant females may be expending more energy to maintaining peace within the captive herd than for supporting reproduction. The goal of this study was to determine if there was a relationship among dominance status, serum cortisol concentrations, and ovarian acyclicity. We hypothesized that adrenal glucocorticoid activity would be increased in dominant, noncycling elephants as compared with subdominant individuals. Blood samples were collected weekly over a 2-year period in 81 females of known dominance and cyclicity status, and analyzed for cortisol. Based on a path analysis model (Reticular Action Model Or Near Approximation [RAMONA]), noncycling, dominant African elephant females did not have higher mean serum cortisol concentrations, or exhibit more variability (i.e., coefficient of variation, standard deviation) in cortisol secretion. This study suggests that alterations in adrenal activity are not related to dominance status nor contribute directly to acyclicity in captive African elephants.

Social factors influence ovarian acyclicity in captive African elephants (Loxodonta africana)

Nearly one-third of reproductive age African elephants in North America that are hormonally monitored fail to exhibit estrous cycle activity, which exacerbates the nonsustainability of the captive population. Three surveys were distributed to facilities housing female African elephants to determine how social and environmental variables contribute to cyclicity problems. Forty-six facilities returned all three surveys providing information on 90% of the SSP population and 106 elephants (64 cycling, 27 noncycling and 15 undetermined). Logistic analyses found that some physiological and social history variables were related to ovarian acyclicity. Females more likely to be acyclic had a larger body mass index and had resided longer at a facility with the same herdmates. Results suggest that controlling the weight of an elephant might be a first step to helping mitigate estrous cycle problems. Data further show that transferring females among facilities has no major impact on ovarian activity. Last, social status appears to impact cyclicity status; at 19 of 21 facilities that housed both cycling and noncycling elephants, the dominant female was acyclic. Further studies on how social and environmental dynamics affect hormone levels in free-living, cycling elephants are needed to determine whether acyclicity is strictly a captivity-related phenomenon.

Nutritional and Behavioral Effects of Gorge and Fast Feeding in Captive Lions

Nonhuman animals in captivity manifest behaviors and physiological conditions that are not common in the wild. Lions in captivity face problems of obesity, inactivity, and stereotypy. To mediate common problems of captive lions, this study implemented a gorge and fast feeding schedule that better models naturalistic patterns: African lions (Panthera leo) gradually adapted from a conventional feeding program to a random gorge and fast feeding schedule. Digestibility increased significantly and food intake and metabolizable energy intake correspondingly decreased. Lions also showed an increase in appetitive active behaviors, no increase in agonistic behavior, and paced half as frequently on fast days as on feeding days. Thus, switching captive lions to a gorge and fast feeding schedule resulted in improved nutritional status and increased activity.

Adaptation of wild-caught Tasmanian devils (Sarcophilus harrisii) to captivity: evidence from physical parameters and plasma cortisol concentrations

This study assessed whether capture and transferral into captivity represents a significant stressor to Tasmanian devils. Four male and four female devils were captured in the wild and housed for 6 months in captivity in male–female pairs. Blood samples were collected for cortisol assay at capture, every 24 h for the first 4 days, and then monthly; body weight and tail width were monitored weekly. In the males, mean plasma cortisol concentrations were highest (49 ± 9.19 ng mL–1) at the time of initial capture; cortisol concentrations declined significantly after 48 h in captivity (9.2 ± 5.96 ng mL–1) and did not change significantly over the months in captivity. Females exhibited a different pattern: plasma cortisol concentrations were highest (74.0 ± 3.24 ng mL–1) in the initial sample, but mean concentrations remained elevated in samples taken at 24, 48 and 96 h after initial capture, and did not exhibit a significant decline (to 20.65 ± 8.95 ng mL–1) until 4 weeks after capture. During the first 2 months in captivity, the male devils lost ~8.7% of their original body weight, and females lost 10.6% during this same period. However, body weights then rose during the rest of the experiment. These results suggest that Tasmanian devils experience elevated plasma cortisol concentrations in response to capture and transfer into captivity. However, these high concentrations are not maintained during 6 months in captivity, suggesting that the animals are not chronically stressed.

Behavioral and developmental consequences of early rearing experience for captive giant pandas (Ailuropoda melanoleuca)

Mother-reared (MR) and peer-reared (PR) captive giant panda (Ailuropoda melanoleuca) cubs were compared to evaluate the effects of early removal from mother on behavioral development. Males and females and twins and singletons were compared to assess the effects of social setting on behavioral development. Subjects included 2 PR females, 3 MR females, 3 MR males, and 3 mothers. MR cubs spent more time manipulating bamboo and fell more often than PR cubs. PR cubs spent more time inactive. Male cubs directed more playful behavior at their mothers. Twins spent more time play fighting with their mothers than with their siblings. The results suggest that peer-rearing does not provide young pandas with the same level of social stimulation as mother-rearing.

Effect of Wood-Pile Feeders on the Behaviour of Captive Bush Dogs (Speothos Venaticos)

The influence of an environmental enrichment programme on the searching behaviour of separate groups of male and female bush dogs at Edinburgh Zoo was evaluated. The enrichment programme involved hiding food in specially constructed wood-piles and other appropriate places in the bush dogs’ enclosures. Behavioural data were recorded morning and afternoon for 20 consecutive experimental days and were compared to pre- and post-enrichment programme data, representing basal conditions. Data were collected over a 10-period for both pre and post enrichment phases. Activities were recorded under seven behavioural categories. There was no significant difference between sexes in the proportion of time spent performing searching behaviour so data were pooled. The enrichment programme appeared to cause an increase (P < 0.01) in searching behaviour from initial basal conditions of 2.7per cent to 6.1 per cent of total recorded data points. There was a subsequent decrease in searching behaviour (P < 0.01) to 2.5 per cent when basal conditions were reinstated. All dogs showed increases in searching behaviour when enrichment and basal data were compared. The effectiveness of the enrichment programme in terms of increasing the proportion of time spent in searching behaviour showed a significant decline (P <0.005) over time, probably relating to the dogs increasing proficiency at finding food. It is suggested that the enhanced levels of searching behaviour represent an improvement in welfare.