The effect of weather on sleep and the welfare of drills in captivity

One of the greatest challenges faced when keeping animals in captivity is maintaining normative behaviours and limiting stereotypies, which is especially difficult in species with a sophisticated social system. The role of key husbandry practices during the daytime, such as environmental enrichment and diverse feeding regimes, is well understood across most species in accredited wildlife facilities. However, less is known about the importance of night-time husbandry and in particular the effect of sleep quality on normative behaviour and stereotypies, or indeed, how external factors, such as the weather, influence sleep quality. The aim of this study was to understand the effect of the weather in Western Europe on the sleep achieved by a troop of drills, an endangered primate species from Africa with advanced sociality, and whether this affected stereotypies, normative behaviours and habitat use. I recorded these behaviours at night using trail cameras and by direct observation during the day after, during 25 day/night focal and scan samples between December 2023-February 2024. Total night-time “sleep” was measured using and combining non-invasive observational methods to create an index of “total sleep”. Because sleep was measured by observation rather than physiologically, it was difficult to be sure whether the drills were fully asleep or resting due to the lighting in the enclosure coupled with their elusive nature and therefore I generated an index of “total sleep” by adding two different behavioural states together: “sleep” and “deep rest”. Weather data was recorded daily from Fota Wildlife Park’s weather station. The results showed that the variation in local weather has a significant effect on total sleep, while also having a strong influence on the expression of stereotypies, normative behaviours and habitat use. Rainfall and increased wind speed correlated negatively with the total sleep achieved by the troop. General linear mixed models showed that the less total sleep the primates achieved at night, the more stereotypies were exhibited that same night and the next day. This study adds to our understanding of primate sleep in captive facilities and suggests practical solutions to improve the welfare of the troop of Mandrillus leucophaeus at Fota Wildlife Park. Specifically, the study suggests that the use of bioactive or “green” roofs consisting of native meadow flower species on the top of the drill housing may help to mitigate the negative effect of inclement weather on primates when sleeping.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2025

Author dc:creator

• Moscarelli, Gary

Advisors dc:contributor.advisor

• Quinn, John
• Ramsay, Ruth

• Zoology
• Primate behaviour
• Primate husbandry
• Animal behaviour
• Animals in captivity

Statement dc:rights

• © 2025, Gary Moscarelli.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/18408

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/18408