Extended incubation recesses in Sanderlings are impacted by temperature and body condition

Complex incubation strategies have evolved to solve the trade-off between
parent survival and care for their eggs with often brief departures
(recesses) that maximise egg survival or infrequent extended recesses
maximising adult condition. Here we examined incubation behaviour of
Sanderlings (Calidris alba), a species that exhibits both bi- and
uniparental incubation behaviour. During 11 breeding seasons in Greenland,
we have quantified incubation variability with thermologgers placed in
nests. We estimated the impact of environmental conditions and individual
characteristics on the occurrence and the duration of recesses. We found
that extended recesses are a unique feature of uniparentals, and their
frequency and duration increased in colder temperatures. The relationship
was mediated by body condition, with individuals in poor condition
performing longer extended recesses in colder temperatures. This suggests
that extended recesses may represent a shift towards self-maintenance at
the expense of the egg care, allowing birds to continue incubating under
unfavourable conditions. Our study illustrates how extended recesses may
be a key breeding strategy to overcome high energetical costs associated
with incubation. Quantifying such behavioural flexibility paves the way
for tracking future behavioural responses of individuals in the face of
changing environments.