Parent–offspring
recognition (POR) is fundamental in colonial birds when the potential
intermingling of chicks is higher due to the large number and proximity of nests.
In species with isolated nests, where chick presence in the nest is strong contextual
evidence of kinship, there might be circumstances when the parent might doubt the
identity of the chick, but not enough to reject it. Olfactory-based
recognition of conspecifics
and nest sites in birds has gained strong evidence suggesting a potential role
of olfaction in POR. Despite that, there are no studies testing it. We used Scopoli's
shearwater (Calonectris diomedea) as model colonial single-brooded
species with a developed
olfactory sense, usually breeding in well-spaced
nests with low probability of
chicks mixing. We tested the parent's ability to selectively respond to their own chick
as opposed to a simpler rule of feeding any chick found in the nest by means of chick-fostering
experiments. We designed two cross-fostering
experiments using chicks of
different ages to test whether the ability of parents to recognize a related chick develops
over time, possibly after acquiring an own distinctive odour. Finally, we also manipulated
nests’ odour to disentangle the confounding effect of nest site recognition
from POR when parents return at night. All experimental chicks were adopted by parents
as the weight and bill growth of cross-fostered
chicks did not differ significantly
from the control group. We recorded a small difference in weight when foster chicks
were inside an odour-manipulated
nest; although we did not record weight loss in
experimental chicks, only a steeper increase in weight was observed in control chicks.
In conclusion, adoption in Scopoli's shearwater seems to follow the rule "if the young is
in my nest, accept it" proposed by Beecher (1991) for species with spatially separated
nests and low chick mobility.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/acceptedVersio