Species-specific demographic and behavioral responses to food availability during migratory stopover

Population Ecology
By: , and 



Understanding the effects of migratory stopover site conditions on both demographic rates and migratory behaviors is critical for interpreting changes in passage population sizes at stopover sites and predicting responses to future changes and conservation actions. We used a Bayesian formulation of the open robust design model to analyze mark-resight observations of three migratory shorebird species using Delaware Bay, USA during spring stopover from 2005 to 2018. We tested for an effect of stopover food availability and weather conditions on survival probability and the probability of returning to this site in the next year and found species differences in these relationships. After years with greater food availability, red knot Calidris canutus rufa had higher survival probability but ruddy turnstone Arenaria interpres were more likely to return to the site. Estimates of within-year probabilities of arrival and persistence at the stopover site showed relatively consistent migration schedules for ruddy turnstone, but more interannual variation for red knot and sanderling Calidris alba. Shorebird use of this site typically peaked during May 26–28, but the estimated proportion of the population present during this period varied dramatically among years for red knot (range: 0.07–0.59) but less so for ruddy turnstone and sanderling. This demonstrates that both the proportion of the flyway population using this stopover site and the proportion present during a given sampling period vary among years, and both should be considered in analyzing and interpreting monitoring data. Stopover conditions can influence both migratory behavior and demographics, underscoring the importance of flyway-wide monitoring.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Species-specific demographic and behavioral responses to food availability during migratory stopover
Series title Population Ecology
DOI 10.1002/1438-390X.12094
Volume 64
Issue 1
Year Published 2022
Language English
Publisher Ecological Society of Japan
Contributing office(s) Coop Res Unit Atlanta, Patuxent Wildlife Research Center
Description 16 p.
First page 19
Last page 34
Country United States
State Delaware, New Jersey
Other Geospatial Delaware Bay
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