“Home alone!” influence of nest parental attendance on offspring behavioral and hormonal stress responses in an Antarctic seabird, the snow petrel (Pagodroma nivea).
Résumé
In altricial species, parents brood their chicks constantly before leaving them unattended sometimes for extended
periods when they become thermally independent. During this second phase, there is sometimes important interindividual
differences in parental attendance and the fitness costs and benefits of parental strategies have previously
been extensively investigated. However, the impact of parental presence on offspring behaviors and
stress physiology has been overlooked. Here, we examined the influence of parental presence on offspring
hormonal and behavioral stress sensitivities in snow petrel chicks. We demonstrated for the first time in a wild
bird species that attended chicks had lower stress-induced corticosterone levels and a lower probability to show
defensive behavior compared to the alone chicks. This reduced stress sensitivity is certainly explained by the
well-known link between corticosterone and nutritional status, and by the recent delivery of meals to the
attended chicks and the improvement of their nutritional status. It may also be explained by the parental protection
against predators or inclement weather, or/and by the psychosocial comfort of parental presence for the
offspring. Overall, these results suggest that the presence of a parent in the nest reduces offspring stress sensitivity
in wild birds. Further studies would now be required to disentangle the impact of nutritional status and
parental presence on stress sensitivity and to better understand the potential impact of parental presence and
circulating corticosterone levels on growth and cognitive development in wild birds.