Going stressed underground: corticosterone-induced stress responses alter the movement and spatial ecology of males in a fossorial reptile.

backgroundIncreased levels of physiological stress caused by environmental perturbations may alter an individual's physiological condition, which in turn may influence its movement and space-use strategies. These effects can vary depending on the environment, context, and lifestyle of each species. However, some animal groups, such as fossorial species, have been rarely examined, even though numerous environmental and anthropogenic factors can strongly affect the quality of the underground soil environment they inhabit.

methodsWe examined how an aspect of the stress response affected the movement and spatial ecology of males in a strictly fossorial reptile, the amphisbaenian Blanus cinereus. Males were subjected to repeated, non-invasive corticosterone (CORT) supplementation, the main hormone mediating the stress response in reptiles. Then, we used passive integrated transponder (PIT) telemetry to track for 14 days the movements and space use of CORT-supplemented and control males, as well as non-CORT manipulated females, while moving undisturbed underground in outdoor seminatural enclosures. We hypothesized that experimentally elevated CORT would alter movement behavior, particularly reducing activity and space use in males.

resultsThe CORT treatment decreased underground movement activity, distances moved, number of movements, and daily areas covered by CORT-supplemented males. However, although all males were in close proximity to females more often than toeach other, there was no effect of CORT supplementation of males on their spatial relationships (distance and proximity) with male and female conspecifics.

conclusionsRepeated elevation of CORT may modify the underground movements and space use of fossorial reptiles, which may represent a strategy to compensate for the effects of glucocorticoid activation on physiological condition and energetic allocation, avoiding predation risk or the energetic costs of burrowing. Our study contributes to understanding the effects of soil environmental perturbations, such as pollution or drought, on the ecology of fossorial animals, and how these species might cope with these potential stressors.