Evaluating the effects of giraffe skin disease and wire snare wounds on the gaits of free-ranging Nubian giraffe.

Giraffe skin disease (GSD), a condition that results in superficial lesions in certain giraffe (Giraffa spp.) populations, has emerged as a potential conservation threat. Preliminary findings suggested that individuals with GSD lesions move with greater difficulty which may in turn reduce their foraging efficiency or make them more vulnerable to predation. A current known threat to some giraffe populations is their mortality associated with entrapment in wire snares, and the morbidity and potential locomotor deficiencies associated with wounds acquired from snares. The goal of our study was to quantify the locomotor kinematics of free-ranging Nubian giraffe (G. camelopardalis camelopardalis) in Murchison Falls National Park (MFNP), Uganda, and compare spatiotemporal limb and neck angle kinematics of healthy giraffe to those of giraffe with GSD lesions, snare wounds, and both GSD lesions and snare wounds. The presence of GSD lesions did not significantly affect spatiotemporal limb kinematic parameters. This finding is potentially because lesions were located primarily on the necks of Nubian giraffe in MFNP. The kinematic parameters of individuals with snare wounds differed from those of healthy individuals, resulting in significantly shorter stride lengths, reduced speed, lower limb phase values, and increased gait asymmetry. Neck angle kinematic parameters did not differ among giraffe categories, which suggests that GSD neck lesions do not impair normal neck movements and range of motion during walking. Overall, MFNP giraffe locomotor patterns are largely conservative between healthy individuals and those with GSD, while individuals with snare wounds showed more discernible kinematic adjustments consistent with unilateral limb injuries. Additional studies are recommended to assess spatiotemporal limb kinematics of giraffe at sites where lesions are found predominantly on the limbs to better assess the potential significance of GSD on their locomotion.

Implementing a low-starch biscuit-free diet in zoo gorillas: the impact on health.

In the wild, western lowland gorillas consume a diet high in fiber and low in caloric density. In contrast, many gorillas in zoos consume a diet that is high-calorie and low in fiber. Some items commonly used in captive gorilla diets contain high levels of starch and sugars, which are minimal in the natural diet of gorillas. There is a growing concern that captive gorillas may qualify as obese. Furthermore, the leading cause of death for adult male gorillas in zoos is heart disease. In humans, a diet that is high in simple carbohydrates is associated with both obesity and the incidence of heart disease. In response to these issues, we implemented a biscuit-free diet (free of biscuits and low in fruit) and measured serum biomarkers of obesity and insulin resistance pre- and post-diet change at three institutions: North Carolina Zoological Garden, Cleveland Metroparks Zoo, and Columbus Zoo and Aquarium. We also added a resistant starch supplement to gorilla diets at two of the above institutions. We anticipated that these diet changes would positively affect biomarkers of obesity and insulin resistance. Both diet manipulations led to a reduction in insulin. Resistant starch also decreased overall serum cholesterol levels. Future research will examine these health changes in a greater number of individuals to determine if the results remain consistent with these preliminary findings.

Implementing a low-starch biscuit-free diet in zoo gorillas: the impact on behavior.

In the wild, western lowland gorillas travel long distances while foraging and consume a diet high in fiber and low in caloric density. In contrast, gorillas in zoos typically consume a diet that is low in fiber and calorically dense. Some items commonly used in captive gorilla diets contain high levels of starch and sugars, which are present at low levels in the natural diet of gorillas. Diet items high in simple carbohydrates are associated with obesity and heart disease in humans. Typical captive gorilla diets may also encourage undesirable behaviors. In response to these issues, we tested the behavioral impact of a diet that was biscuit-free, had low caloric density, and which was higher in volume at five institutions. We hypothesized that this diet change would reduce abnormal behaviors such as regurgitation and reingestion (R/R), decrease time spent inactive, and increase time spent feeding. The biscuit-free diet significantly reduced (and in the case of one zoo eliminated) R/R and may have reduced hair-plucking behavior. However, an increase in coprophagy was observed in many individuals following the diet change. The experimental diet caused a general increase in time the gorillas spent feeding, but this increase did not occur across all institutions and varied by individual. Interestingly, the overall time gorillas spent inactive actually increased with this diet change. Future research will examine these behavioral changes in a greater number of individuals to determine if the results remain consistent with these preliminary findings. Additionally, future research will examine the physiological impact of this diet change.

Urinary androgen and corticoid levels in captive, male Western lowland gorillas (Gorilla g. gorilla): age- and social group-related differences.

Urinary androgen and corticoid levels were measured for 52 captive male Western lowland gorillas to examine age-related variance and potential differences resulting from various social situations. Significant diurnal variation was present in both hormones. Age-related differences in androgens revealed that males experienced two stages of androgen increase and one stage of decrease: increases occurred from juvenile (less than 10 yr of age) to subadult (between 10-13 yr) and subadult to young adult (14-20 yr), whereas decreases occurred from young adult to adult (> 20 yr). Age-related differences in corticoid levels varied depending on the time of day, but morning corticoids were greatest in juvenile males, followed by young adult males. The type of social grouping was associated with differences in corticoid levels, as animals housed socially (in either a heterosexual or all-male group) had similar corticoid levels, whereas solitary males showed greater corticoid levels than their socially-housed counterparts. The increased levels of corticoids in solitary-housed males suggest this management strategy might not be optimal, although more data are needed. Additionally, the significantly greater levels of androgens and corticoids in young adult male gorillas may present management challenges, and thus zoos may need to consider increasing the flexibility of their current management practices with respect to males.

A preliminary behavioral comparison of two captive all-male gorilla groups.

Gorillas live in polygamous harem groups, generally composed of one male, several adult females, and their offspring. With an equal numbers of male and female gorillas born in captivity, however, housing gorillas in social breeding units inevitably means that some males will not have access to female social partners. Thus, the future of the captive gorilla population depends on the collective ability of zoos to house equal numbers of males and females. This study examined the behavioral profiles of two all-male groups of captive lowland gorillas (Gorilla gorilla gorilla) to provide information on this type of housing situation. One group consisted of three subadult individuals, while the other consisted of two subadults and a silverback. Data were collected during two 6-month intervals, for a total of 284 hr. The behavioral profiles of the animals were stable over the course of the study but proximity patterns changed. Differences in feeding, solitary play, and object-directed behavior were found between groups, while no significant differences were observed in affiliative or agonistic social behavior. At both institutions, group cohesion appeared to be high, particularly between subadults; these individuals spent approximately 10% of their time engaging in social behavior and 25-50% of their time in close proximity (within 5 m). However, the Zoo Atlanta males spent significantly more time within 1 m and 5 m of each other than the Santa Barbara males, which may reflect a higher level of cohesiveness among members of the Zoo Atlanta group. The behavioral profiles of the animals in this study were similar to those found in bachelor groups of wild mountain gorillas. One notable exception was the absence of homosexual behavior between the silverback and subadults in Santa Barbara and the low frequency of this behavior between subadults in both groups. Although more longitudinal data are needed, these data suggest that all-male groups can be a feasible housing strategy for males at certain periods of their life span. Zoo Biol 20:27-40, 2001. Copyright 2001 Wiley-Liss, Inc.