Data from: Males migrate farther than females in a differential migrant: an examination of the fasting endurance hypothesis

Patterns of migration including connectivity between breeding and
non-breeding populations and intraspecific variation in the distance
travelled are important to study because they can affect individual
fitness and population dynamics. Using data from 182 band recoveries
across North America and 17 light-level geolocators, we examined the
migration patterns of the northern flicker (Colaptes auratus), a migratory
woodpecker. This species is unusual among birds because males invest more
in parental care than females. Breeding latitude was positively correlated
to migration distance because populations in the north appeared to travel
farther distances than southern populations to find wintering locations
with little snow cover. Connectivity was strong for populations west and
east of the Continental Divide. Contrary to the three main hypotheses for
intraspecific variation in migration distance, females wintered, on
average, farther north than males, although there was overlap throughout
their non-breeding range. This pattern contradicts those of other species
found to date and is most consistent with the fasting endurance hypothesis
if investment in parental care depletes the energy reserves of male
flickers more than females. We thus propose a new factor, parental effort,
which may influence optimal wintering areas and migration strategies
within birds, and encourage future experimental studies to test the
relationship between parental care roles and migration strategies of the
sexes.