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Data from: Developing a Stopover-CORT hypothesis: corticosterone predicts body composition and refueling rate in Gray Catbirds during migratory stopover

Citation

DeSimone, Joely et al. (2020), Data from: Developing a Stopover-CORT hypothesis: corticosterone predicts body composition and refueling rate in Gray Catbirds during migratory stopover, Dryad, Dataset, https://doi.org/10.5061/dryad.41ns1rnbb

Abstract

Migratory flight is energetically challenging, requiring alternating phases of fuel catabolism and fuel accumulation, accompanied by dramatic changes in body composition and behavior. Baseline corticosterone (CORT; the primary glucocorticoid in birds) is thought to underlie transitions between fuel catabolism during flight, fuel deposition during stopover, and the initiation of migratory flight. However, studies of CORT on stopover physiology and behavior remain disparate efforts, lacking the cohesion of a general hypothesis. Here we develop a Stopover-CORT hypothesis formalizing the relationships among CORT, body condition, and refueling rate in migratory birds. First we expect body mass to increase with triglycerides (TRIG) as birds refuel. Second, based on a synthesis of previous literature, we predict a U-shaped CORT curve over the course of stopover, postulating that elevated CORT at arrival is reactive, responding to poor body condition, while CORT elevation before departure is preparative, driving changes in behavior and body condition. We tested these predictions in Gray Catbirds (Dumetella carolinensis) following a trans-Gulf flight during spring migration. We found baseline CORT was negatively correlated with body condition and TRIG, corresponding with our predictions for arriving and refueling—but not departing—birds. It is possible catbirds undergo regional habitat translocations rather than complete the entire stopover phase at our study site. We propose the Stopover-CORT hypothesis as a useful predictive framework for future studies of the mechanistic basis of stopover physiology. By studying the regulation of stopover refueling and departure, we may better understand physiological limitations to overall migration rate and improve assessments of habitat quality for refueling birds.

Usage Notes

min_day_of_stopover: The minimum possible day of stopover, based on recapture data (=days since initial capture)

CORT_adj: the value used in analyses--raw CORT data from the assay, adjusted for recoveries

QMR_Mean_Lean and QMR_Mean_Fat: the average lean mass and fat mass values from repeated (2-3) QMR scans for each individual

Min_to_bleed: the blood sample was collected this many minutes after the bird's capture was observed

Bleed_Time_min: the time of day (in minutes) when the blood sample was collected

atypical: whether or not the individual was considered to have body composition not typical of a trans-Gulf migrant, based on lean mass residuals and fat mass (see Methods)

Funding

National Science Foundation, Award: NSF IOS-1656726