Man O’ War on Your Shore?

By: Juliana Coffey

On Thursday, November 17, several Magnificent Frigatebirds (Fregata magnificens) were observed near the main jetty in Mayreau, St. Vincent and the Grenadines, in pursuit of some fisheries discards.  One particular individual bore a yellow tag on each wing with corresponding letter and number codes.  These codes detail its personal identity within a doctoral research project being conducted by Sarah Trefry at the University of New Brunswick in Canada.  This project aims to determine where frigatebirds go when they are not at their breeding colonies, as well as attempts to understand the size differences between adult male and females, a characteristic not usually seen in seabirds.

This project is being conducted in Barbuda, which has the largest Frigatebird colony in the region.  So far, there have been over three hundred male and female birds tagged.  Sarah has received reports of over a hundred re-sightings as far north as Florida, throughout the Lesser Antilles, and as far south as French Guyana.  Some birds have been sighted numerous times, which can shed light on an individual’s movement patterns over time.  This particular individual, an adult female, was tagged in Barbuda in 2009, seen in Guadeloupe in May 2009, back on Barbuda in 2010, in Guadeloupe again in early 2011, and has now made its way to the Grenadines.

Speculation also exists on the differences of breeding frequency between male and female frigatebirds.  A female frigatebird lays one egg at a time, which may take up to almost two months to hatch, and more than a year to become independent.  The female accompanies the immature bird throughout its first year, teaching it how to survive, while the male leaves the colony early in the chick’s life stage.  One theory is that males may breed numerous times within one year, while the female, occupied with her fledgling, breeds every other year.  In fact, one of Sarah’s tagged males from Barbuda, later attempted to breed at a colony off French Guyana.  This information has management implications for the species, and suggests that there is a meta-population of frigatebirds in the Caribbean, rather than specific populations defined by breeding colonies.

Frigatebirds feed primarily on fish, and are known to regularly attack other birds, forcing them to either drop or regurgitate their catches which can then easily be scooped up.  This behaviour has earned them the name “Man O’ War” bird throughout the region.  As their feathers are not waterproof, they cannot land in the water, meaning that all foraging antics must occur during flight.  Frigatebirds have been known to be almost constantly on the wing, utilizing thermals for travel, and are quite regularly seen along coastlines or at sea.  If you live or are traveling in the region and see any frigatebirds with tags, please report your sighting.

For more information on this project, or to report a sighting, please visit http://www.unb.ca/acwern/people/strefry.htm

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