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Advisor(s)
Abstract(s)
Brood-guarding (or the continual attendance at
the nest by one parent) has been relatively little studied in
altricial birds. Parental investment in brood-guarding is
often highly variable within a species, and the study of
such variability may contribute to the understanding of the
functions and regulation of this behaviour and of the tradeoffs
involved in the choice between attending the nest and
leaving to forage. In some colonial birds, it has been found
that early nesting pairs attend their chick for longer than
later nesting counterparts, giving rise to the synchronisation
hypothesis that suggests that early pairs prolong broodguarding
in order to reduce the probability of nest
predation by a dilution effect. In this paper, for the first
time we test the prediction that burrow-nesting colonial
birds subject to little predation pressure should not display
a seasonal decline in brood-guarding duration. The growth
assistance hypothesis suggests that brood-guarding may
allow the provision of frequent small meals and the efficient
use of energy by chicks with poor homeothermic
capabilities, resulting in improved early chick-growth.
Finally, the chick-protection hypothesis predicts that chicks
in more exposed nests should be brood-guarded for longer.
Data collected at two Cory’s Shearwater Calonectris diomedea colonies situated in contrasting environments
supported the synchronisation hypothesis, as there was no
seasonal trend in brood-guarding duration. Contrary to the
growth assistance hypothesis, chicks brood-guarded for
longer periods did not have an improved growth (in one
colony there was even a negative effect of brood-guarding
on early chick development). Finally, we found no difference
in brood-guarding between nests with contrasting
levels of exposure to potential predators and weather.
Despite confirming the prediction of the synchronisation
hypothesis, more research is needed to identify the main
factors underlying the variability of brood-guarding
observed in this and other studies.
Description
Keywords
Parental care Brooding Synchronisation hypothesis
Citation
Journal of Ornithology, 150, 103-108