Data from: Incubation temperature affects growth and energy metabolism in blue tit nestlings

Because the maintenance of proper developmental temperatures during avian
incubation is costly to parents, embryos of many species experience
pronounced variation in incubation temperature. However, the effects of
such temperature variation on nestling development remain relatively
unexplored. To investigate this we artificially incubated wild blue tit
(Cyanistes caeruleus L.) clutches at 35.0 °C, 36.5 °C or 38.0 °C during
two thirds of the incubation period. We returned clutches to their
original nests prior to hatching and subsequently recorded nestling growth
and resting metabolic rate. The length of the incubation period decreased
with temperature whereas hatching success increased.. Nestlings from the
lowest incubation temperature had shorter tarsus length at two weeks of
age, but body mass and wing length were not affected by temperature. In
addition, nestlings from the lowest temperature had a significantly higher
resting metabolic rate compared to mid and high temperature nestlings,
which may partly explain observed size differences between groups. These
findings suggest that nest microclimate can influence nestling phenotype,
but whether observed differences carry over to later life-history stages
remains unknown.