Comparative androgen and glucocorticoid profiles of male hellbenders (Cryptobranchus alleganiensis) engaging in paternal care or filial cannibalism across a land-use gradient

Filial cannibalism has been studied in numerous contexts, but outside of brood-cycling teleosts, nothing is known about the hormone-behavior relationships that influence whole-clutch filial cannibalism, or how these relationships might vary across a gradient of habitat disturbance. To address this question, we examined the androgens and glucocorticoids of male hellbenders engaged in paternal care or whole-clutch filial cannibalism in successfully reproducing populations, and in reaches where high rates of whole-clutch filial cannibalism, geriatric demography, and reproductive failure are associated with reduced riparian forest cover. As nests were initiated, males’ androgens did not differ with forest cover, but successful males’ androgens tended to be ~50% higher than cannibals, though this difference was only statistically significant for DHT. At nest initiation and one month into care, there was no difference in the detection frequency of baseline cortisol between nest fates, or across forest cover. However, one month into care, the lowest forest cover cannibalistic males exhibited a significantly higher cortisol stress response (by ~40%) compared to successful and cannibalistic males from reaches with the highest forest cover. During this same period, we also observed an interaction between males’ total length and their cortisol stress response. Specifically, at lower forest cover, smaller (i.e., younger) males exhibited a greater stress response than larger (i.e., older) individuals. At high forest cover, the opposite was true. Our findings describe how an unorthodox mechanism of parental care failure may be characterized by interrelated relationships between hormones and land use, influencing the reproductive success of an imperiled vertebrate.<br>