Novel measures of continental‐scale avian migration phenology related to proximate environmental cues

Abstract

Rapid changes in seasonal avian migrations provide compelling examples of biotic response to climate change. Seasonal waves of land surface phenology and temperature are thought to be primary exogenous cues that migrants use to fine tune migration timing. Exploration of the role that these cues play in regulating migration timing requires better spatial, temporal, and taxonomic sampling than is typically available. We analyze weather surveillance radar (WSR) and eBird citizen science data in an effort to understand the macroscale relationships among migration phenology, seasonal waves of land surface phenology and seasonality of temperature. We demonstrate that both WSR and eBird data provide similar estimates of migration timing at local (within 100 km) and macro scales (>20° of latitude). These measures of avian phenology were positively correlated with spring temperatures and land surface phenology (extended spring index of first leaf date), which followed a south to north wave. Start‐of‐spring, estimated from a remotely sensed index of vegetation greenness, did not show the expected pattern from south to north and appears unlikely to be a useful exogenous migration cue within the study region. Future analyses of WSR and eBird data have the potential to provide high‐resolution phenology data that may be useful in understanding spatiotemporal dynamics of migration systems and the response of these systems to climate change.

Cold spell en route delays spring arrival and decreases apparent survival in a long-distance migratory songbird

“…Nearctic-Neotropical long-distance migrants have been shown to use environmental cues to some extent to adjust their migration rate in spring [20, 21]. On the contrary, pied flycatchers Ficedula hypoleuca were not able to adjust the arrival time proportionally to the increasing spring temperatures suggesting a tight endogenous routine controlling phenology of spring migration in that population [22].…”

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

“…Furthermore, although radar data have limited utility for representing species identities, we can build an index of system‐based phenology by integrating eBird and WSR data. The integration of these datasets is revealing new insights into macroscale movements (Horton et al, ; Kelly et al, ; La Sorte, Hochachka, Farnsworth, Sheldon, Van Doren, et al, ; La Sorte, Hochachka, Farnsworth, Sheldon, Fink, et al, ) and can add taxonomic resolution to the rich archive of WSR data. To date, such efforts have been primarily proofs‐of‐concept that this approach can capture properties of complex assemblages of biotic and abiotic factors that characterize multidimensional systems, heralding a new paradigm that combines data‐intensive science and ecology (Hochachka et al, ; Kelling et al, ).…”

Habitat‐ and species‐mediated short‐ and long‐term distributional changes in waterbird abundance linked to variation in European winter weather

“…Accumulating evidence shows that changes in climatic conditions have become a major threat to the maintenance of biodiversity (Parmesan & Yohe, ; Thomas & Williamson, ) and responses to such changes are already apparent among many taxa (Amano et al., ; Chen, Hill, Ohlemüller, Roy, & Thomas, ; Hughes, ; Knudsen et al., ; Parmesan, ). Common responses to climate change are, for example, adjustments to timing of phenological events, such as flowering (Frei, Ghazoul, Matter, Heggli, & Pluess, ; Menzel et al., ) or migration time (Kelly et al., ; Møller, Rubolini, & Lehikoinen, ; Møller, Rubolini, & Saino, ) or changes in distribution (Amano et al., ; Thomas et al., ).…”