Data from: Connecting the dots: Stopover strategies of an intercontinental migratory songbird in the context of the annual cycle
Paxton, Kristina L., University of Southern Mississippi
Moore, Frank R., University of Southern Mississippi
Published Jul 24, 2017 on Dryad.
Cite this dataset
Paxton, Kristina L.; Moore, Frank R. (2017). Data from: Connecting the dots: Stopover strategies of an intercontinental migratory songbird in the context of the annual cycle [Dataset]. Dryad. https://doi.org/10.5061/dryad.5804c
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.
BAWW Data Set
Data 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.
National Science Foundation, Award: IOS 0844703 and IOS 1110655