Use of a Florida Gulf Coast Barrier Island by Spring Trans-Gulf Migrants and the Projected Effects of Sea Level Rise on Habitat Availability

Abstract

Barrier islands on the north coast of the Gulf of Mexico are an internationally important coastal resource. Each spring hundreds of thousands of Nearctic-Neotropical songbirds crossing the Gulf of Mexico during spring migration use these islands because they provide the first landfall for individuals following a trans-Gulf migratory route. The effects of climate change, particularly sea level rise, may negatively impact habitat availability for migrants on barrier islands. Our objectives were (1) to confirm the use of St. George Island, Florida by trans-Gulf migrants and (2) to determine whether forested stopover habitat will be available for migrants on St. George Island following sea level rise. We used avian transect data, geographic information systems, remote sensing, and simulation modelling to investigate the potential effects of three different sea level rise scenarios (0.28 m, 0.82 m, and 2 m) on habitat availability for trans-Gulf migrants. We found considerable use of the island by spring trans-Gulf migrants. Migrants were most abundant in areas with low elevation, high canopy height, and high coverage of forests and scrub/shrub. A substantial percentage of forest (44%) will be lost by 2100 assuming moderate sea level rise (0.82 m). Thus, as sea level rise progresses, less forests will be available for migrants during stopover. Many migratory bird species’ populations are declining, and degradation of barrier island stopover habitat may further increase the cost of migration for many individuals. To preserve this coastal resource, conservation and wise management of migratory stopover areas, especially near ecological barriers like the Gulf of Mexico, will be essential as sea levels rise.

Is there more than one way to cross the Caribbean Sea? Migratory strategies of Nearctic‐Neotropical landbirds departing from northern Colombia

“…The results for the gray-cheeked thrush coincide with previous studies by Bayly et al (2013) and Gómez et al (2017), while for yellow-billed cuckoos this represents a novel contribution to our knowledge of the species' migration routes and flight capacity. Sechrist et al (2012) reported a possible spring migration route from Colombia and Venezuela across the Caribbean to the Yucatan Peninsula in western yellow-billed cuckoos, while the occurrence of emaciated cuckoos on the Gulf barrier islands (Lester et al 2016) also suggests birds may make direct flights to the Gulf Coast. However, more research is necessary to understand the spring migration of both western and eastern breeding populations of this species.…”

“…In the Americas, a large percentage of migratory passerines fly across the Gulf of Mexico as they move between breeding and stationary non-breeding grounds (La Sorte et al 2016). In recognition of this movement, much research has focused on the conservation importance of the northern Gulf coast for providing essential refuelling sites prior to departure across the Gulf of Mexico in autumn and on arrival in spring (Buler et al 2007, Lester et al 2016, Cohen et al 2017. In comparison, there has been far less research on the stopover ecology and migratory strategies of approximately 50 species that winter or stopover in northern South America prior to crossing the Caribbean Sea as they return to the breeding grounds in spring (Bayly et al 2018).…”

The Impact of Lidar Elevation Uncertainty on Mapping Intertidal Habitats on Barrier Islands

“…On barrier islands, supratidal areas include habitats such as beach, dune, and barrier flat (meadow, nonvegetated barrier flat, and forest). Monitoring these supratidal areas is equally important to resource managers [4] because these areas provide important habitat for resident and migratory shorebirds [46], neotropical migrants [47], and sea turtles [48]. Besides providing habitat for wildlife, dunes deliver erosion control for shorelines [49].…”

Florida's Strategic Position for Collaborative Automated Telemetry Tracking of Avian Movements Across the Americas

“…The increased concentration of migrants moving through Florida also conveys a potential for increased susceptibility to multiple environmental stressors. Impacts of global climate change may disproportionately affect low-lying areas that provide important stopover habitats (Lester et al 2016). Other factors such as rapid coastal development (Johnson and Barbour 1990;Kautz 1993) and recently heightened harmful algal blooms (Perkins 2019) make Florida's coastal birds particularly vulnerable.…”