Sleep monitoring of an Asian elephant Elephas maximus calf at Night Safari, Singapore: testing whether sleep time is a significant predictor of cortisol or the onset of positive elephant endotheliotropic herpesvirus viraemia

Abstract

A number of methods for measuring the welfare of elephants in human care have been used within zoological associations and rescue centres worldwide. The measurement of glucocorticoids in relation to stress has been particularly well validated. Measuring stress is especially important for Asian elephant Elephas maximus calves between one and 8 years of age which are highly susceptible to developing elephant endotheliotropic herpesvirus (EEHV) haemorrhagic disease. Sleep monitoring has been used as a possible means of assessing the welfare state of animals, although the efficacy of this method has not been validated. Our aim was to test whether sleep time or cortisol provided the most significant predictor for the onset of positive EEHV blood viraemia in a 2 year‐old calf at Night Safari, Singapore. Faecal samples were collected twice per week and assayed for glucocorticoids. Using closed‐circuit television, the time the calf slept each night was measured between December 2017 and September 2018. Sleep was not a predictor of viraemia nor of cortisol concentration in this study. However, cortisol appeared to be related to the occurrence of viraemia.

Social and environmental impacts on sleep in captive Asian elephants (Elephas maximus)

“…In recent studies of elephant welfare in captivity, the emphasis has turned to the measurement of rest and sleep behaviors (Kalirathinam, Elangkovan, Kawi, & Cabana, 2019; Schiffmann et al, 2018a; Schiffmann, Hård, Hjelm, & Clauss, 2020; Schiffmann, Knibbs, Clauss, Merrington, & Beasley, 2018b; Walsh, 2017; Williams, Bremner‐Harrison, Harvey, Evison, & Yon, 2015) as it could be a valuable noninvasive measure of potential stressors. Sleep is an important aspect of life, and deprivation can lead to acute and chronic health issues for animals (Bryant, Trinder, & Curtis, 2004; Hillman et al, 2018; Walsh, Binding, & Holmes, 2019) and indicate signs of psychological and physical stress (Abou‐Ismail, Burman, Nicol, & Mendl, 2007).…”

Monitoring Technologies for Animal Welfare: A Review of Aspirations and Deployments in Zoos

“…[36] identified costs, maintenance logistics, and location as issues and recommended use for easily identifiable behaviours. [37] used CCTV for sleep monitoring combined with cortisol measuring for stress testing to assess animal welfare states.…”

“…Combining Systems: Adaptive modular systems would enable various sensor systems to be combined, proving useful as would combining monitoring methods, e.g., mixing sleep observation with cortisol readings (#1 zoo) [37]. Continuing modification and integration of simple modular systems proves promising.…”

“…Smaller mobile modular solutions can sometimes be the most useful [31], [32]. Where existing systems can be updated, modified, and/or coupled with several systems offers flexibility and expands data collection capabilities [37]. Digital cameras to track cardiopulmonary readings offer basic health checks [52].…”

Editorial: Conservation of Elephants

“…Elephant endotheliotropic herpesvirus haemorrhagic disease (EEHV‐HD) continues to be a threat to both zoo and free‐living elephants, particularly targeting Asian elephants of 1–13 years of age. Kalirathinam et al () at Singapore Night Safari have been looking for indicators that predict the onset of EEHV‐HD so that treatment therapies can be initiated at the earliest juncture. The aetiology of EEHV requires further study and research such as this contributes to the knowledge available to elephant caretakers, veterinarians and researchers when they have to care for an elephant with EEHV‐HD.…”