Energy allocation is revealed while behavioural performance persists after fire disturbance

Abstract

Metabolic physiology and animal behaviour are often considered to be linked, positively or negatively, according to either the performance or allocation models. Performance seems to predominate over allocation in natural systems, but, the constraining environmental context may reveal allocation limitations to energetically expensive behaviours. Habitat disturbance, like the large-scale fire that burnt wetlands of Biebrza National Park (NE Poland), degrades natural ecosystems. It arguably reduces food and shelters availability, modifies predator-prey interactions, and poses direct threat for animals survival, such as to the wetland specialist root vole (Microtus oeconomus). We hypothesized that fire disturbance induce physiology-behaviour co-expression, as a consequence of changed environmental context. We repeatedly measured maintenance and exercise metabolism, and behavioural responses to open field, in a root voles from post-fire and unburnt locations. Highly repeatable maintenance metabolism and distance moved during behavioural test correlated positively, but relatively labile exercise metabolism did not covary with behaviour. At the same time, voles from post-fire habitat had higher maintenance metabolism and moved shorter distances than voles from unburnt areas. We conclude a prevalence of the performance mechanism, but simultaneous manifestation of context-dependent allocation constraints of the physiology-behaviour covariation after disturbance. The last occur at the within-individual level indicating the significance of behavioural plasticity in context of environmental disturbance.