DOI: 10.5061/dryad.5804c
title: Data from: Connecting the dots: Stopover strategies of an intercontinental migratory songbird in the context of the annual cycle

description: The phases of the annual cycle for migratory species are inextricably
 linked. Yet, less than five percent of ecological studies examine seasonal
 interactions. In this study, we utilized stable hydrogen isotopes to
 geographically link individual black-and-white warblers (Mniotilta varia)
 captured during spring migration with breeding destinations to understand
 a migrant's stopover strategy in the context of other phases of the
 annual cycle. We found that stopover strategy is not only a function of a
 bird's current energetic state, but also the distance remaining to
 breeding destination and a bird's time-schedule, which has previously
 been linked to habitat conditions experienced in the preceding phase of
 the annual cycle. Birds in close proximity to their breeding destination
 accumulate additional energy reserves prior to arrival on the breeding
 grounds, as reflected by higher migratory condition upon arrival, higher
 refueling rates measured via blood plasma metabolites, and longer stopover
 durations compared to birds migrating to breeding destinations farther
 from the stopover site. However, late birds near their breeding
 destination were more likely to depart on the day of arrival (i.e.,
 transients), and among birds that stopped over at the site, the average
 duration of stopover was almost half the time of early conspecifics,
 suggesting late birds are trying to catch-up with the overall
 time-schedule of migration for optimal arrival time on the breeding
 grounds. In contrast, birds with long distances remaining to breeding
 destinations were more likely to depart on the day of arrival and
 primarily used stopover to rest before quickly resuming migration,
 adopting similar strategies regardless of a bird's time-schedule. Our
 study demonstrates that migrants adjust their en route strategies in
 relation to their time-schedule and distance remaining to their breeding
 destination, highlighting that strategies of migration should be examined
 in the context of other phases of the annual cycle.
description: BAWW Data
 SetData was collected in
 the field. BirdID is the unique identifier of each black-and-white warbler
 that was sampled during the study. The study was conducted over 4 years
 (y1=2008, y2=2009, y3=2010, y4=2011). A bird's breeding destination
 (North=boreal forest of Canada, South=southeastern U.S.) is based on
 stable hydrogen isotope values of a bird's tail feather. The timing
 of migration (Early, Mid, Late) for each individual is based on the range
 of capture dates for each sex in a given breeding destination and in a
 given year. Blood plasma metabolite concentrations of triglycerides (TRIG)
 and β-hydroxy-butyrate (BOH) were collected via brachial vein puncture. A
 Principal Component Analysis was conducted on plasma metabolite levels and
 the 1st principal component axis (PC1) was used as a measure of refueling
 with positive values representing increasing TRIG levels and decreasing
 BOH levels. The time between blood sampling and sunrise (Day.Time) and
 capture time (Bleed.Time) were recorded to determine their influence on
 blood plasma metabolite values. Only a subset of birds captured had TRIG
 and BOH measurements and therefore some fields indicate NA because plasma
 metabolite data was not included in analyses. Stopover duration estimates
 (Stopover) were calculated with program MARK. Condition is a size-specific
 condition index value. Age and sex of the warbler are also
 included.Dyrad_BAWWdatabase.csv