Data from: Migratory shorebird adheres to Bergmann’s Rule by responding to environmental conditions through the annual lifecycle

The inverse relationship between body size and environmental temperature
is a widespread ecogeographic pattern. However, the underlying forces that
produce this pattern are unclear in many taxa. Expectations are
particularly unclear for migratory species, as individuals may escape
environmental extremes and reorient themselves along the environmental
gradient. In addition, some aspects of body size are largely fixed while
others are environmentally flexible and may vary seasonally. Here, we used
a long‐term dataset that tracked multiple populations of the migratory
piping plover Charadrius melodus across their breeding and non‐breeding
ranges to investigate ecogeographic patterns of phenotypically flexible
(body mass) and fixed (wing length) size traits in relation to latitude
(Bergmann's Rule), environmental temperature (heat conservation
hypothesis), and migratory distance. We found that body mass was
correlated with both latitude and temperature across the breeding and
non‐breeding ranges, which is consistent with predictions of
Bergmann's Rule and heat conservation. However, wing length was
correlated with latitude and temperature only on the breeding range. This
discrepancy resulted from low migratory connectivity across seasons and
the tendency for individuals with longer wings to migrate farther than
those with shorter wings. Ultimately, these results suggest that wing
length may be driven more by conditions experienced during the breeding
season or trade‐offs related to migration, whereas body mass is modified
by environmental conditions experienced throughout the annual lifecycle.