Investigating the impact of rank and ovarian activity on the social behavior of captive female African elephants

Abstract

Over a third of captive female African elephants in North America fail to exhibit normal estrous cycles based on long‐term serum progestagen analyses. Why acyclicity occurs is unknown; however, the majority of noncycling females are ranked by keepers as the dominant individual within the group. To investigate the relationship between ovarian cyclicity status and keeper‐determined social rank, observations were conducted on 33 female African elephants (18 cycling, 15 noncycling). Based on keeper evaluations, five cycling elephants were ranked dominant, seven in the middle and six as subordinate. In contrast, 10 noncycling elephants were ranked as dominate and five as subordinate with none ranked as middle. When comparing the behavior of the elephants by their keeper‐determined rank, the dominant females dominant were significantly more likely to approach, displace and push. Similarly, keeper‐determined subordinate females more frequently presented their hind end and held their ears erect. Behaviors initiated by one elephant toward another did not vary between cycling and noncycling females, except when the interaction with social rank was tested. Dominant, noncycling females initiated a higher percentage of “approach” and “displace” behaviors than both cycling and noncycling, subordinate elephants. Subordinate, noncycling elephants displayed the highest percentage of “ears erect.” Social rank drives the interactions of ex situ female African elephants more than ovarian cyclicity status. Thus, behavioral interactions cannot be used to predict which cycling elephants are most likely to become acyclic. Zoo Biol 29:154–167, 2010. © 2009 Wiley‐Liss, Inc.

Results of the third reproductive assessment survey of north American Asian (Elephas maximus) and African (Loxodonta africana) female elephants

“…It was originally believed that elephant females were either cyclic or acyclic [Brown, 2000], but now many Asian and African cows have been shown to alter between periods of normal cyclicity and irregular or acyclicity during the prime reproductive years (11–35 years of age). Research over the past 10 years have investigated possible causative factors for abnormal cyclicity, such as seasonality [Bechert et al, 1999], herd rank and time spent outdoors [Schulte et al, 2000], and behavioral influences of herd mates [Freeman et al, 2004, 2009, 2010]. Wild elephants are generally not considered seasonal breeders, although fluctuations in estrus activity can occur during times of climate change, i.e., drought and monsoon seasons [Douglas‐Hamilton, 1975; Moss, 1983].…”

“…It has been previously shown that captive females who hold dominant herd status are more prone to be acyclic [Freeman et al, 2004, 2010]. But according to the 2008 survey data, the majority of acyclic Asian and African elephants were ranked in the middle category.…”

Habituation to Auditory Stimuli by Captive African Elephants (Loxodonta africana)

“…Although resources are typically abundant, competition can still occur between elephants in captivity [Freeman et al, 2010] and in the wild [Archie et al, 2006]. In this study, there was only one pile of hay available during control sound and experimental sound trials.…”

Group management influences reproductive function of the male cheetah (Acinonyx jubatus)

“…As has been discovered for a host of wildlife species, the challenge with such studies is that social hierarchy is not simply a reflection of bouts of overt aggression, but rather a culmination of subtle or affiliative interactions among group mates (Sapolsky 1990;Virgin and Sapolsky 1997;Burks et al 2004;Creel 2005;Freeman et al 2010). This probably has been best studied in species like the African elephant (Loxodonta africana) where higher social rank is expressed by one individual approaching herd-mates and initiating a behavioural interaction (Freeman et al 2010). The outcome of such an interface can then be related to reproductive success.…”