Connectivity of wood thrush breeding, wintering, and migration sites based on range‐wide tracking

Abstract

Many migratory animals are experiencing rapid population declines, but migration data with the geographic scope and resolution to quantify the complex network of movements between breeding and nonbreeding regions are often lacking. Determining the most frequently used migration routes and nonbreeding regions for a species is critical for understanding population dynamics and making effective conservation decisions. We tracked the migration of individual Wood Thrushes (Hylocichla mustelina) (n = 102) from across their range with light-level geolocators and, for the first time, quantified migration routes and wintering regions for distinct breeding populations. We identified regional and species-level migratory connectivity networks for this declining songbird by combining our tracking results with range-wide breeding abundance estimates and forest cover data. More than 50% of the species occupied the eastern wintering range (Honduras to Costa Rica), a region that includes only one-third of all wintering habitat and that is undergoing intensive deforestation. We estimated that half of all Wood Thrushes in North America migrate south through Florida in fall, whereas in spring approximately 73% funnel northward through a narrow span along the central U.S. Gulf Coast (88-93°W). Identifying migratory networks is a critical step for conservation of songbirds and we demonstrated with Wood Thrushes how it can highlight conservation hotspots for regional populations and species as a whole.

The strength of migratory connectivity for birds en route to breeding through the Gulf of Mexico

“…For all three of these species, western breeding populations predominately winter further west in Central America and Mexico while central and eastern breeding populations predominately winter in the Caribbean (American redstart and ovenbird) or further east in Central America (wood thrush) (Norris et al 2006, Rushing et al 2014, Stanley et al 2015, Haché et al 2017. For all three of these species, western breeding populations predominately winter further west in Central America and Mexico while central and eastern breeding populations predominately winter in the Caribbean (American redstart and ovenbird) or further east in Central America (wood thrush) (Norris et al 2006, Rushing et al 2014, Stanley et al 2015, Haché et al 2017.…”

“…All three of these species have some degree of differentiation between breeding and wintering ranges (Norris et al 2006, Hallworth and Marra 2015, Stanley et al 2015 and breeding populations of American redstarts and ovenbirds differ in spring migration passage timing through one GOM site (Langin et al 2009). Therefore, we estimated migratory connectivity for three species of longdistance Neotropical-Nearctic migratory birds, American redstart, ovenbird Seiurus aurocapilla, and wood thrush Hylocichla mustelina, as they traverse the northern coast of the Gulf of Mexico (GOM) in spring.…”

Wind conditions and geography shape the first outbound migration of juvenile honey buzzards and their distribution across sub-Saharan Africa

“…Although there are exceptions where strong connectivity between breeding and non-breeding sites exists [2,3], in most migrant landbirds, individuals from different breeding populations are likely to mix during the non-breeding season. We also know that migrant landbirds are typically highly faithful to individual breeding and non-breeding sites, temporarily residing in two or more areas along their individual migration cycle [4].…”

Towards the Automatic Classification of Avian Flight Calls for Bioacoustic Monitoring

“…These sources include weather surveillance radar, which provides insight into the density, direction, and speed of bird movements but little to no information about the species actually migrating [9], tracking devices that provide information about the location and activity of individuals but little information about population behaviors, marking (e.g. banding, ringing, or color marking) and later recapturing individuals, with similar constraints, stable isotope tracking of the changes in key elements to define movements of birds [10, 11], and crowdsourced human observations, made almost exclusively during daytime hours and of limited use for studying nocturnal migratory flights other than by proxy [12]. Automatic bioacoustic monitoring and analysis is a complementary solution that could be scalable and produce species-specific information otherwise impossible to obtain from any of the previously mentioned methods.…”