Investigating the Effect of Disturbance on Prey Consumption in Captive Congo Caecilians Herpele squalostoma

Kimberley C Carter,Mark Wilkinson,Léa Fieschi-Méric,David J Gower,Christopher J Michaels,Francesca Servini,Benjamin Tapley

doi:10.3390/jzbg2040050

Abstract

Maintaining Gymnophiona in captivity provides opportunities to study the behaviour and life-history of this poorly known Order, and to investigate and provide species-appropriate welfare guidelines, which are currently lacking. This study focuses on the terrestrial caecilian Herpele squalostoma to investigate its sensitivity to disturbances associated with routine husbandry needed for monitoring and maintaining adequate wellbeing in captivity. Fossorial caecilians gradually pollute their environment in captivity with waste products, and substrate must be replaced at intervals; doing so disturbs the animals directly and via destruction of burrow networks. As inappetence is frequently associated with stress in amphibians, the percentage consumption of offered food types, river shrimp (Palaemon varians) and brown crickets (Gryllus assimilis), was measured as an indicator of putative stress following three routine substrate changes up to 297 days post-substrate change. Mean daily variation in substrate temperatures were also recorded in order to account for environmental influences on food consumption, along with nitrogenous waste in tank substrate prior to a substrate change and fresh top soil in order to understand the trade-off between dealing with waste accumulation and disturbing animals. We found a significant negative effect of substrate disturbance on food intake, but no significant effect of prey type. Variations in daily soil temperatures did not have a significant effect on food intake, but mean substrate temperature did. Additionally, substrate nitrogenous waste testing indicated little difference between fresh and tank substrate. In conclusion, this study provides a basis from which to develop further welfare assessment for this and other rarely kept and rarely observed terrestrial caecilian species.

Highlights

Within zoos and other industries maintaining wild animals in captivity, there is a necessary balance to be struck between providing husbandry needs for captive animals and reducing negative effects that such provision may elicit [1]
Chronic stress may be visible in amphibians through reduced feeding, behavioural inhibition or decreased activity, hiding, fearfulness, frequency of startle responses, stereotypies, raised or changed posture and/or displacement behaviours [5,6,7,8]
This study evaluates the effects of disturbance from three substrate change events on the food consumption in H. squalostoma

Summary

Introduction

Within zoos and other industries maintaining wild animals in captivity, there is a necessary balance to be struck between providing husbandry needs for captive animals and reducing negative effects that such provision may elicit [1]. A frequency of twice daily checks is not feasible either due to the species’ natural history making them difficult to visually monitor e.g., fossorial, or because such checks are intrusive and cause significant stress to the animals. Most disturbances such as enclosure changes, handling and restraining, and transportation are temporary and create a short-term change in behavioural responses and glucocorticoid hormone production [3,4]. Chronic stress may be visible in amphibians through reduced feeding, behavioural inhibi- Frequent negative events can cause chronic stress, which in turn causes negative morphological and behavioural responses.

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Conclusion