With the ability to stay aloft over water for weeks at a
time, we can assume that Magnificent Frigatebirds usually fare well when
displaced by hurricanes. We observed this survival strategy with one of our own
GPS/satellite-tracked Magnificent Frigatebirds in September 2017 as Hurricane
Irma moved northward up peninsular Florida’s Gulf coast.
ARCI has been collaborating for seven years with the U.S.
Fish and Wildlife Service’s Florida Keys National Wildlife Refuge Complex in
deploying satellite/GPS tracking units on Magnificent Frigatebirds captured at winter
roosts in the Florida Keys and at the only U.S. nesting location, a colony of
just 100 pairs in the Dry Tortugas. This information has helped us determine
for the first time where the wintering birds breed, where the breeding birds
overwinter, patterns of seasonal movements, fidelity to roost sites, and
survivorship.
Dry Tortugas Male
was captured on 15 May, 2013, as a breeding bird and tracked every day for the
last 4.5 years! You can follow his movements,
along with those of all the other tagged birds monitored as part of ARCI’s
research, by visiting this page on ARCI’s website.
Unlike the non-breeding Magnificent Frigatebirds that roost
and feed within the lower Florida Keys and nest in the western Caribbean
(Yucatan Peninsula of Mexico and Cuba), the breeding birds from the lone U.S.
colony on the Dry Tortugas stay close to the coast of peninsular Florida when
not bound by nesting obligations.
As we documented over the previous 4 years, the Dry Tortugas
male had been spending the non-breeding season, since 10 June 2017, foraging
out over the Gulf of Mexico from small mangrove islands that line peninsular
Florida’s western coast. At 6:45 pm on 8 September, Dry Tortugas male was near
the mouth of Crystal River about 38 miles north of Irma’s eye as it moved northward
across the Florida Straits. About 22 hours later, Irma made landfall near
Naples, Florida, and continued northward along Florida’s west coast.
By this time, the Dry Tortugas male was almost certainly
being exposed to winds of at least 55 MPH.
When it became impossible to grip the vegetation in its mangrove-forest
roost, this bird took to the sky to glide downwind to safety as Hurricane Irma
passed.
Over the next 2.5 hours, Dry Tortugas male used Irma’s strong
winds to fly almost 160 miles southwest out into the Gulf of Mexico and away
from the severe winds generated close to storm’s eye. Here, he was even closer
to the hurricane, 120 miles from the eye. In 6 hours, Dry Tortugas male had
traveled an additional 110 miles southwest before turning eastward on favorable
tailwinds that carried him to Pine Island in Lee County, Florida. His journey from
Crystal River to Pine Island was completed in a little more than 9 hours. He
wasted little time before heading north back to his wintering area near Crystal
River.
Overall, this Magnificent Frigatebird’s hurricane detour was
a 650-mile round-trip that lasted a little over 2 days. A mere inconvenience? A free ride?
In any case, a very different strategy for outliving a hurricane
compared with the behavior of most of the other birds whose movements we have
documented with remote telemetry.
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| Dry Tortugas Male's movements as he evaded Hurricane Irma in September 2017. |
