Activity budgets, responses to disturbance and novel behaviours in captive mountain chicken frogs Leptodactylus fallax

Abstract

Mountain chicken frogs Leptodactylus fallax are assessed as Critically Endangered on the IUCN Red List due to threats including chytridiomycosis and habitat loss. Ex-situ populations underpin species survival, but captive management is hampered by incomplete species knowledge, including its behavioural biology. In sixteen adult frogs, we investigated enclosure usage, nocturnal activity budgets, and behavioural responses to varying levels of husbandry-related disturbance through instantaneous scan sampling of camera trap footage over forty-two consecutive nights. Enclosure usage was quantified through the application of modified Spread of Participation Indices (mSPI). We present the first detailed activity budgets published for this species and found that broad activity patterns of captive animals corresponded well with their wild conspecifics; taking refuge during the day and emerging at dusk into exposed areas of the enclosure. Some behaviours, especially hunting and bathing, were partially phased throughout the nocturnal period. Enclosure use was not even, with disproportionately large amounts of time spent using nest boxes and deep leaf litter, even at night, and the converse in thin leaf litter and elevated perches. Principal Components Analysis (PCA) identified a bold-shy behavioural grouping (movement and resting opposed to refuge behaviours) that was consistent across husbandry-related disturbance conditions. Randomisation analyses showed that disturbance significantly affected multiple measured behaviour, especially feeding, social interactions and vocalisation; the impact was associated with the degree of disturbance. Novel behaviours were also documented, which are thought to be related to courtship. Our data provide insights into the behaviour of mountain chicken frogs and highlight potential trade-offs between enclosure maintenance, veterinary intervention, and animal welfare. Keywords: Amphibians, behaviour, mSPI, disturbance, welfare, Zoo