When elephants fall asleep: A literature review on elephant rest with case studies on elephant falling bouts, and practical solutions for zoo elephants

Abstract

Little attention has been paid to the resting and sleeping behavior of zoo elephants so far. An important concern is when elephants avoid lying down, due to degenerative joint and foot disease, social structure, or stressful environmental changes. Inability or unwillingness to lie down for resting is an important welfare issue, as it may impair sleep. We emphasize the importance of satisfying rest in elephants by reviewing the literature on resting behavior in elephants (Loxodonta africana and Elephas maximus) as well as the documentation of four cases from European zoos and our own direct observations in a zoo group of four female African elephants during 12 entire days. The common denominator in the case reports is the occurrence of a falling bout out of a standing position subsequently to a cessation of lying rest for different periods of time. Although well-known in horses as "episodic collapse" or "excessive drowsiness," this syndrome has not been described in elephants before. To enable its detection, we recommend nocturnal video monitoring for elephant-keeping institutions. The literature evaluation as well as own observational data suggest an inverse relationship between lying rest and standing rest. Preventative measures consist of enclosure modifications that facilitate lying rest (e.g., sand hills) or standing rest in a leaning position as a substitute. Anecdotal observations suggest that the provision of appropriate horizontal environmental structures may encourage safe, sleep-conducive standing rest. We provide drawings on how to install such structures. Effects of providing such structures should be evaluated in the future.

Soft and persistent—The influence of sand‐flooring and calves on the resting behavior of a zoo‐kept African elephant (Loxodonta africana) group

“…In zoo‐kept elephants of both species ( Elephas maximus and Loxodonta africana ), resting behavior represents a meaningful welfare indicator (Williams, Chadwick, Yon, & Asher, ). Lying rest in particular seems to be of utmost importance, and a lack of it might lead to severe alterations of an elephant's health status (Schiffmann et al, ). Hard and inappropriate substrates (e.g., concrete) function as a critical factor in making an elephant reluctant to have lying rest (Roocroft, ; Walsh, ) and might cause secondary medical issues (e.g., pressure sores of the skin; tusk and nail alterations).…”

Sleep‐related behaviors in zoo‐housed giraffes (Giraffa camelopardalis reticulata): Basic characteristics and effects of season and parturition

“…Furthermore, the individual characteristics of animals can also influence their sleep behaviors. For example, recent reviews have reported that health issues, reproductive status, and parturition affect the sleep behaviors of captive African and Asian elephants (Schiffmann et al, ), and social rank influences the duration of sleep in gelada baboons ( Theropithecus gelada ; Noser, Gygax, & Tobler, ). However, few studies have investigated factors that affect the quality of sleep in giraffes, with only one study by Sicks () having investigated the relationship between PS and stress events (transport, malnutrition in newborns, and changes in herd structure).…”

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

“…Neha slept in recumbent position, as is expected from young and healthy individuals (Schiffmann, Hoby et al , ). Her average of 219·5 minutes per night is at the lower end of the sleep times recorded by other studies; however, it is still within normal parameters.…”

“…Monitoring an elephant’s sleep may not be determinant of the root cause of discomfort; however, it may be a key leading indicator that something is amiss [sleepy–lethargic, no sleep at all, mild gastrointestinal signs (e.g. constipation, diarrhoea), lameness/stiff leg] and be flagged for early investigation (see Schiffmann, Hoby et al , for a review). If sleep is linked with stress, it may also have significant repercussions on the animal’s welfare state.…”