Satellite-tracking gives fascinating insights for international Magnificent Frigatebird conservation efforts

We are in our second year of a satellite-tracking study of Magnificent Frigatebirds to determine where these birds breed, the timing of migration from roosts to breeding areas, patterns of seasonal movements, fidelity to roost sites, and survivorship.

Movements of four Magnificent Frigatebirds tracked by satellite from the lower Florida Keys from 28 April 2014 through 10 June 2014.

Two of the satellite-tracked Magnificent Frigatebirds that nested in the western Caribbean have begun moving back to their non-breeding-season home in the lower Florida Keys, where we tagged five of them in October 2012 (we since lost the signal of one in Nicaragua).

For two years now, their movements have suggested that they nested on Isla Contoy off of the northeastern shoreline of Mexico’s Yucatan Peninsula. The male, Keys #9, continually made 400-mile round-trip foraging flights west along the coast, while the female’s (Keys #6) foraging range was due north into the Gulf of Mexico.

Keys #9 wandered back to the Florida Keys on 27 April, but only stayed a week before returning to the Yucatan. There, still restless, he took another flight to Florida 10 days later, this time to Boca Grand Island off of Charlotte County, quickly returned to the Yucatan four days later, then flew back to the lower Florida Keys on 30 May. Keys #6 made a direct flight to the lower Florida Keys on 6 June.

Two other tagged females are still on their breeding-season ranges, one (Keys #7) near the eastern Yucatan and one (Keys #5) off the southern coast of Cuba. We expect that, like the two from Isla Contoy, they will soon move abruptly to the waters surrounding the western Florida Keys.

All satellite-GPS locations for the two Magnificent Frigatebirds in the Dry Tortugas tagged on 15 May 2013 through 28 May 2014.

Neither of the two frigatebirds we tagged a year ago in the Dry Tortugas, site of the only U.S. breeding colony, appears to have nested in 2014 (females nest every other year because of the lengthy dependency of their single juvenile; less is known the about breeding efforts of males). The female spent her entire year in the vicinity of the Tortugas colony, an area only occasionally used by the Caribbean breeders that ‘winter’ in the nearby lower Keys. The male, on the other hand, has ranged from the Tortugas to northern Florida, making regular coastal excursions from Cedar Key on the Gulf to Melbourne on the Atlantic side.

Tracking these Magnificent Frigatebirds has provided fascinating insights that contribute directly to international conservation efforts for this species. We feel very fortunate for all we’ve learned during the short span of this study, and also for the privilege of sharing this new knowledge with those studying the species in the Caribbean.

ARCI recently was invited to collaborate on an existing study of Magnificent Frigatebirds nesting in a colony of 1,200 pairs in the British Virgin Islands (BVI), where we assisted with some of their tagging efforts. This multi-national team consists of Dr. Patrick Jodice, leader of the South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University; Dr. Louise Soanes, University of Liverpool, UK; Dr. Jennifer Bright, Royal Society for the Protection of Birds, UK; and Susan Zaluski, Executive Director of the Jost Van Dyke Preservation Society, BVI.

These dedicated researchers represent a larger community of ecologists focusing on the conservation ecology of imperiled seabirds. Their skills and experience provide a valuable perspective for comparative data analyses and interpretations, and an excellent opportunity for us to examine our Florida seabird data in the context of global threats, management needs, and conservation planning. We are grateful for this opportunity to collaborate.