Physiological Stress and Refuge Behavior by African Elephants

Abstract

Physiological stress responses allow individuals to adapt to changes in their status or surroundings, but chronic exposure to stressors could have detrimental effects. Increased stress hormone secretion leads to short-term escape behavior; however, no studies have assessed the potential of longer-term escape behavior, when individuals are in a chronic physiological state. Such refuge behavior is likely to take two forms, where an individual or population restricts its space use patterns spatially (spatial refuge hypothesis), or alters its use of space temporally (temporal refuge hypothesis). We tested the spatial and temporal refuge hypotheses by comparing space use patterns among three African elephant populations maintaining different fecal glucocorticoid metabolite (FGM) concentrations. In support of the spatial refuge hypothesis, the elephant population that maintained elevated FGM concentrations (iSimangaliso) used 20% less of its reserve than did an elephant population with lower FGM concentrations (Pilanesberg) in a reserve of similar size, and 43% less than elephants in the smaller Phinda reserve. We found mixed support for the temporal refuge hypothesis; home range sizes in the iSimangaliso population did not differ by day compared to nighttime, but elephants used areas within their home ranges differently between day and night. Elephants in all three reserves generally selected forest and woodland habitats over grasslands, but elephants in iSimangaliso selected exotic forest plantations over native habitat types. Our findings suggest that chronic stress is associated with restricted space use and altered habitat preferences that resemble a facultative refuge behavioral response. Elephants can maintain elevated FGM levels for ≥6 years following translocation, during which they exhibit refuge behavior that is likely a result of human disturbance and habitat conditions. Wildlife managers planning to translocate animals, or to initiate other management activities that could result in chronic stress responses, should consider the potential for, and consequences of, refuge behavior.

Delayed physiological acclimatization by African elephants following reintroduction

“…FGMs were 23% higher during the dry season than the wet season (F1,1560 = 30.55, P < 0.0001). By contrast, samples from Phinda and Pilanesberg tended to have FGMs 16-45% lower, and on average (Wasser et al, 2000;Jachowski et al, 2012). 2).…”

“…These attacks, linked with abnormally elevated testosterone levels and prolonged periods of musth in young bulls, were remedied by the introduction of large adult bulls that suppressed the musth patterns in younger bulls (Slotow et al, 2000). These patterns of female aggression, combined with reclusive behavior, have been linked to elevated glucocorticoid stress hormone concentrations (Jachowski, Millspaugh & Slotow, 2012). These patterns of female aggression, combined with reclusive behavior, have been linked to elevated glucocorticoid stress hormone concentrations (Jachowski, Millspaugh & Slotow, 2012).…”

“…In South Africa, in the case of at least two attempts to move elephants to new environments, stress hormone levels increased dramatically during translocation and subsequently declined to baseline conditions within 30 days post-translocation (Millspaugh et al, 2007;Viljoen et al, 2008). animals released into an area where a population was previously extirpated) into a fenced environment, stress hormone values remained elevated for up to 6 years following reintroduction (Jachowski et al, 2012). In the case of at least one translocated wild elephant population that was a true reintroduction (i.e.…”

Wild Herbivore Grazing Enhances Insect Diversity over Livestock Grazing in an African Grassland System

“…This is likely due to the movement patterns of mammals. For example, elephants use shelter provided by the exotic trees and thickets in and around the ENs in preference to overall lower number of shelter patches in the PA [64]. We have also observed this general trend for other large animals in the area, although this was not empirically tested.…”

LACK OF SPATIAL AND BEHAVIORAL RESPONSES TO IMMUNOCONTRACEPTION APPLICATION IN AFRICAN ELEPHANTS (LOXODONTA AFRICANA)

“…19, 37 Generally, though, conservationists argue based on ecological reasons when attempting to manage the effects of elephants (i.e., the ability of elephants to influence biodiversity through changes to species composition, vegetation structure, and functioning of the ecosystem by virtue of their feeding habits). 16,39 However, nonconsumptive, sustainable-use approaches practiced by many South African reserves focus on tourism products as a valid land-use option (e.g., privately owned white rhinos offer primarily financial objectives, over and above their conservation contribution, and comprised 24.1% of all white rhinos (Certotherium simun) in South Africa during 2010).…”