Physiological Stress and Refuge Behavior by African Elephants

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

Multilevel Societies in Primates and Other Mammals: Introduction to the Special Issue

# The Author(s) 2012. This article is published with open access at Springerlink.co

Large carnivores in the Tarangire ecosystem

We synthesize data on the ecology of large carnivores in the Tarangire Ecosystem (TE). Despite anthropogenic pressures, all large carnivore species (lions Panthera leo, spotted hyena Crocuta crocuta, striped hyena Hyena hyena, leopard Panthera pardus, cheetah Acinonyx jubatus, and wild dog Lycaon pictus) have persisted in this fragmented ecosystem consisting of multiple protected areas among a matrix of village lands. The focal species were widely distributed across land-use gradients. While the comparatively abundant spotted hyena permanently occupied village lands, other species only sporadically used these human-dominated areas. Across species, carnivores used village lands more frequently during the rainy season, possibly following seasonal shifts in the movement of prey species. These processes can increase human-carnivore interactions, expanding the potential for conflict. In some areas, leopards, lions, and striped hyenas reached high densities, whereas cheetahs and wild dogs occurred patchily and at low densities. Our review suggests that the existence of diverse protected areas contribute to the persistence of the large carnivore community. The persistence of lions, cheetahs, and wild dogs appears dependent on human-induced mortality and prey depletion. Conserving large carnivores in TE requires the application of interventions that reduce human-induced mortality while simultaneously conserving the spatio-temporal distributions of prey species

Organization and chemical neuroanatomy of the African elephant (Loxodonta africana) hippocampus

Elephants are thought to possess excellent long-term spatial–temporal and social memory, both memory types being at least in part hippocampus dependent. Although the hippocampus has been extensively studied in common laboratory mammalian species and humans, much less is known about comparative hippocampal neuroanatomy, and specifically that of the elephant. Moreover, the data available regarding hippocampal size of the elephant are inconsistent. The aim of the current study was to re-examine hippocampal size and provide a detailed neuroanatomical description of the hippocampus in the African elephant. In order to examine the hippocampal size the perfusion-fixed brains of three wild-caught adult male African elephants, aged 20–30 years, underwent MRI scanning. For the neuroanatomical description brain sections containing the hippocampus were stained for Nissl, myelin, calbindin, calretinin, parvalbumin and doublecortin. This study demonstrates that the elephant hippocampus is not unduly enlarged, nor specifically unusual in its internal morphology. The elephant hippocampus has a volume of 10.84 ± 0.33 cm³ and is slightly larger than the human hippocampus (10.23 cm3). Histological analysis revealed the typical trilaminated architecture of the dentate gyrus (DG) and the cornu ammonis (CA), although the molecular layer of the dentate gyrus appears to have supernumerary sublaminae compared to other mammals. The three main architectonic fields of the cornu ammonis (CA1, CA2, and CA3) could be clearly distinguished. Doublecortin immunostaining revealed the presence of adult neurogenesis in the elephant hippocampus. Thus, the elephant exhibits, for the most part, what might be considered a typically mammalian hippocampus in terms of both size and architectur