A quantitative field study of paternal care in Ozark hellbenders, North America’s giant salamanders

Abstract

Paternal care is relatively uncommon in tetrapods but appears to be the rule in the large aquatic salamanders of the primitive family Cryptobranchidae (North America: hellbenders, genus Cryptobranchus; Asia: giant salamanders, genus Andrias). For the Ozark hellbender, C. alleganiensis bishopi, a federally endangered subspecies, anecdotal observations of paternal care have been reported, but no quantitative assessments have been made. We quantified behavior of a guarding male hellbender from video footage collected over 6 weeks in 2008 from a naturally occurring nest. We quantified behavior of the guarding male to help develop hypotheses about costs and benefits of paternal care. Overall, there were high frequencies of tail fanning of the eggs and rocking behaviors (rhythmic, lateral back-and-forth movements of the body), which increase aeration of the nest. The male rarely left the nest unguarded and spent over half of the recorded time at the nest exposed at the nest entrance. Potential egg predators observed included centrarchid, cyprinid, ictalurid, and percid fishes, with centrarchids being the most common and exhibiting the most interest in the nest. The frequency of foraging by the male was low (n = 8 strikes at identifiable prey), with a 37% success rate. The male was observed to consume seven of his eggs. Our data represent the first systematic analysis of paternal care of Ozark hellbenders and elucidate some of the costs (low foraging success, potential energetic costs of tail fanning and rocking) and benefits (aeration of eggs, protection from egg predators) of paternal care.