Corticosterone Metabolite Concentration Is Not Related to Problem Solving in the Fawn-Footed Mosaic-Tailed Rat Melomys Cervinipes

Abstract

Animals can respond physiologically, such as by adjusting glucocorticoid hormone concentrations, to sudden environmental challenges. These physiological changes can then affect behavioural and cognitive responses. While the relationships between adrenocortical activity and behaviour and cognition are well documented, results are equivocal, suggesting species-specific responses. We investigated whether adrenocortical activity, measured using corticosterone metabolite concentration, was related to problem solving in an Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). Mosaic-tailed rats live in complex environments that are prone to disturbance, suggesting a potential need to solve novel problems, and have been found to show relationships between physiology and other behaviours. We measured problem solving using five food-baited puzzles (matchbox and cylinder in the home cage, and activity board with pillars to push, tiles to slide and levers to lift in an open field), and an escape-motivated obstruction task in a light/dark box. Faecal samples were collected from individuals during routine cage cleaning. Adrenocortical activity was evaluated non-invasively by measuring faecal corticosterone metabolites using an enzyme immunoassay, which was biochemically and biologically validated. Despite varying over time, adrenocortical activity was not significantly related to problem solving success or time spent interacting for any task. However, as adrenocortical activity is reflective of multiple physiological processes, including stress and metabolism, future studies should consider how other measures of physiology are also linked to problem solving.

Problem solving of wild animals in the Wet Tropics of Queensland, Australia

“…The findings from the present study support our previous work (e.g. Rowell et al, 2022; Rowell & Rymer, 2021b), and suggest that, at least for some species, problem solving ability in captivity is likely also reflective of problem solving ability in the wild, similar to those studies shown for personality traits in blue tits Cyanistes caeruleus (Herborn et al, 2010) and African striped mice Rhabdomys pumilio (Yuen et al, 2016).…”

Physiological response after translocation differs between source populations in a threatened mammal

“…We found no difference in FGMs between female and male GSNRs, which is comparable to other rodent species such as the fawn-footed mosaic-tailed rat Melomys cervinipes [ 56 ] and Eurasian red squirrel Sciurus vulgaris [ 57 ]. While our study did not look at reproductive condition (such as the different stages of oestrous), its impacts on FGMs are well documented [ 57 – 59 ] and warrant further investigation in this species.…”