# Lunar synchrony, geography, and individual clocks shape autumn migration timing in an avian migrant * all data are GPS locations and dates used for the investigation of the influence of full moon, sampling location, and individual repeatability on whip-poor-will autumn migration timing * all data are from adult male whip-poor-wills * data have been summarized from a more comprehensive GPS tracking dataset; these data have been filtered to include only the necessary data used in analyses * Antrostomus vociferus is currently listed as "Near-threatened" by the IUCN. Therefore, no GPS locations for exact breeding sites are included in the dataset. Locations in the departure dataset are for the first lat/lon recorded after each bird departed its breeding site * data contact: Alicia Korpach, **Data file: stopovers_EWPW.csv** -GPS locations for every stopover site from birds for which we had full migration tracks. -Includes dates and durations of stopover. -Only includes stopovers longer than one day in duration (i.e. locations where birds spent one full day between flight bouts). That is why some stopovers for each bird appear to be missing (i.e. some StopOrder values will be excluded). * IID: independent ID number * band_tag: individual birds’ federal band number and GPS tag number * group: north or south sampling group * StopOrder: Stopover order from breeding to wintering sites. * n_points: GPS points collected at the stopover site * StopDuration_days: number of days bird spent at the stopover site * stopover_start: date of arrival to stopover site * stopover_end: date of departure from stopover site * lat: latitude * lon: longitude * Year: year data were collected **Data file: departures_EWPW.csv** dates of breeding site departures * IID: independent ID number * lat: latitude of first location after departing from the breeding site\ * lon: longitude of first location after departing from the breeding site * bandnum: individual birds’ federal band number * group: north or south sampling group * Repeat: whether this was not a repeat track (0), or a first (1) or second (2) repeat track * Year: year data were collected * depnight: date of departure night * ordinal: date in ordinal format * SeptFM: September full moon date in ordinal format **Data file: latcrossings_EWPW.csv** First GPS locations and dates after crossing various latitudes during southbound autumn migration * IID: independent ID number * lat: latitude of bird at first location after crossing the reference latitude * lon: longitude of bird at first location after crossing the reference longitude * bandnum: individual birds’ federal band number * group: north or south sampling group * degrees: reference latitude * year: year data were collected * date: date of crossing reference latitude * ordinal: date in ordinal format **Data file: arrivals_EWPW.csv** GPS locations and dates of winter site arrivals * IID: independent ID number * lat: latitude * lon: longitude * bandnum: individual birds’ federal band number * group: north or south sampling group * Repeat: whether this was not a repeat track (0), or a first (1) or second (2) repeat track * Year: year data were collected * arrnight: date of arrival night * ordinal: date in ordinal format * SeptFM: September full moon date in ordinal format

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.