Long‐Term Impacts of Poaching on Relatedness, Stress Physiology, and Reproductive Output of Adult Female African Elephants

Abstract

Widespread poaching prior to the 1989 ivory ban greatly altered the demographic structure of matrilineal African elephant (Loxodonta africana) family groups in many populations by decreasing the number of old, adult females. We assessed the long-term impacts of poaching by investigating genetic, physiological, and reproductive correlates of a disturbed social structure resulting from heavy poaching of an African elephant population in Mikumi National Park, Tanzania, prior to 1989. We examined fecal glucocorticoid levels and reproductive output among 218 adult female elephants from 109 groups differing in size, age structure, and average genetic relatedness over 25 months from 2003 to 2005. The distribution in group size has changed little since 1989, but the number of families with tusked old matriarchs has increased by 14.2%. Females from groups that lacked an old matriarch, first-order adult relatives, and strong social bonds had significantly higher fecal glucocorticoid values than those from groups with these features (all females R(2)= 0.31; females in multiadult groups R(2)= 0.46). Females that frequented isolated areas with historically high poaching risk had higher fecal glucocorticoid values than those in low poaching risk areas. Females with weak bonds and low group relatedness had significantly lower reproductive output (R(2)[U]=0.21). Females from disrupted groups, defined as having observed average group relatedness 1 SD below the expected mean for a simulated unpoached family, had significantly lower reproductive output than females from intact groups, despite many being in their reproductive prime. These results suggest that long-term negative impacts from poaching of old, related matriarchs have persisted among adult female elephants 1.5 decades after the 1989 ivory ban was implemented.

Assessing the effect of roads on impala (Aepyceros melampus) stress levels using faecal glucocorticoid metabolites

“…Depending on how animals react to poachers, it is therefore a possibility that poaching influence FGM levels. African elephants have shown increased FGM levels in areas with higher poaching risk (Gobush et al 2008;Tingvold et al 2013). However, poaching is unlikely to be the only factor causing stress, because West and Central have the highest FGM levels, while poaching is linked to the areas on the western side of the park (Holmern et al 2004;Metzger et al 2007).…”

Can We Sustainably Harvest Ivory?

“…This is very far from our sustainable harvest estimates (Figure 4). These estimates do not account for population variance in tusk size and tusklessness [16], indirect social effects of the harvest [17] and abiotic effects on demography [11]. Climate predictions show that droughts will intensify and become more frequent [18] hence the population trajectory we simulated is liberal (note how we are not capturing extreme changes, Figure 1C).…”

How should the psychological well‐being of zoo elephants be objectively investigated?

“…Wildcaught Asian timber elephants, who experience very stressful ''breaking'' processes followed by high mortality rates, have lower fecundity than captive-bred animals working in the same conditions [Mar, 2007]. Furthermore, in wild African elephants, females from herds socially disrupted by poaching, show low calf outputs, despite being in their reproductive prime [Gobush et al, 2008]. However, despite the research reviewed above on the assessment of HPA activity, and despite preliminary work to develop assays for stress-activated proteins in African elephants [Bechert and Southern, 2002], only one laboratory, Janine Brown's, has investigated possible links between stress and reproductive success in zoo elephants.…”