Data from: Lunar synchrony, geography, and individual clocks shape autumn migration timing in an avian migrant

Timing programs in animal migrants have been selected to synchronize
movements that coincide with predictable resources on the breeding and
nonbreeding grounds. Migrants face potential temporal conflicts if their
migration schedules benefit from synchrony to conflicting rhythms
associated with annual biogeographical (circannual) cues, lunar
(circalunar) cues, or individually-repeatable internal clocks. We
repeat-tracked individuals of an avian lunaphilic species, Eastern
Whip-poor-will (Antrostomus vociferus), for 2–3 successive autumn
migrations to determine the influence of the lunar cycle, breeding
location, and individual repeatability on migration timing. Almost all
birds avoided departing for migration during a full moon, likely to take
advantage of the bright moonlight to facilitate visual foraging and
enhance pre-migration fattening. However, groups from two
latitudinally-distant sampling areas adjusted their autumn departure
timing differently relative to the timing of the September full moon,
presumably due to differences in seasonal prey availability. Individual
repeatability increased throughout autumn migration, suggesting that the
factors responsible for shaping migration timing may differ for different
migration stages. Our results, that lunar synchrony, local climate, and
individual internal clocks appeared to account for much of the variation
in migration timing in whip-poor-wills, underscore the value of measuring
potentially interacting factors that shape migratory behavior at species,
group, and individual levels. It remains unclear if, or how, maintaining
individually-repeatable annual migration schedules provides an adaptive
benefit for whip-poor-wills or other lunaphilic migrants. Further
clarifying the reasons for phenotypic variation in whip-poor-will
migration timing will improve predictions of their abilities to adjust
migratory movements under changing environmental conditions.