Endangered Kirtland’s Warbler Makes Unexpected Debut in Jamaica

Scientists aren't sure whether the appearance is a range expansion or a migration mishap. Either way, it's a sign of the species' recovery.

Inching along a line of mist nets in the thickets of western Jamaica, Alicia Brunner spotted something that didn't look quite right.

After several years of working in the mangroves and logwood scrub forests of Font Hill Nature Preserve studying Swainson's Warblers for her master's degree, Brunner's eye is attuned to the foraging styles of common songbirds like American Redstarts, Prairie Warblers, Ovenbirds, and Northern Waterthrushes. So, when she saw a fairly large, strikingly yellow warbler feeding near the ground by her nets, it didn't compute. None of the species on Brunner's radar had its combination of field marks and behavior. She raised her binoculars, and made ornithological history.

“It never even crossed my mind that it could be a Kirtland's Warbler,” the research assistant and bander for the Smithsonian Migratory Bird Center (SMBC) says. “However, once I got my binoculars on her, it was clear she couldn't really be anything else.” Not only had Brunner found one of the rarest birds in the Western Hemisphere, she'd also discovered the first one ever seen in Jamaica—and in one of the most heavily studied patches of forest in the Caribbean, at that.

It's the kind of record that might invite skepticism. Kirtland's Warblers, after all, are federally endangered; their population numbers in the low thousands, and they nest in only a small region along the western Great Lakes. Virtually the entire population winters in the central Bahamas, more than 400 miles north of Font Hill. But the birding world doesn't have to take Brunner's word for it.

“I knew this was a once-in-a-lifetime chance for me to catch this bird in Jamaica. So, I started ‘pishing’ to get her interested, and she responded exactly how I wanted her to,” Brunner wrote over email. “She was curious and came chipping directly at me. I then simply walked towards her, making sure to guide her into the net” to quickly collect some data. Once in hand, Brunner identified the Kirtland’s as a likely young female (though juvenile males can look similar). The close-up photos that she posted on Twitter set off a storm of excitement—fueled, in part, by the scientist’s own glee.

Proving that the universe has a sense of humor, Brunner's capture came a mere day after her SMBC colleagues published what they thought was the definitive scientific paper describing the Kirtland’s winter range and habitat. “It's a little ironic, that's for sure,” says Nathan Cooper, one of the co-authors, who worked for years at Font Hill and continues to study the species in Michigan and the Bahamas. He suspects Brunner's warbler is simply an errant migrant, but does admit that his team has evidence that a few Kirtland's winter in Cuba, the next island north of Jamaica. The habitat at the preserve, however, is different than the species’ typical arid scrub habitat. “It’s much taller canopy than anything I've seen in the Bahamas: a more open understory, yet still pretty scrubby and dense,” Cooper says.

Peter Marra, who directs SMBC and has spent years working in Jamaica himself, doesn't think the single sighting means there's an undiscovered population of the species on the island. “These are migratory birds; they go in some strange directions sometimes,” he says. “If it signifies anything, it's that Kirtland's Warblers are increasing in number.” In 1974, only 167 singing males could be found on the breeding grounds; today, the population is up to about 5,000 individuals due to intensive conservation efforts. “They're popping up in Wisconsin; they're popping up in Ontario,” Marra says. Brunner's bird may have been pushed into Jamaica by increasingly crowded conditions on the wintering grounds, or it may have suffered from an off-kilter compass. Either way, it and a handful of other unusual recent records—from Florida, from Bermuda, from Cuba—suggest the warblers may be expanding their horizons.

Perhaps just in time, too. Climate models suggest that much of the Bahamas, most of which lies three feet or less above sea level, will be inundated in the coming decades, taking with it much of the Kirtland's Warbler's habitat. “In the next 50 years, the [country] will be 50 percent smaller than it is now,” Marra says. “But [the birds are] seeding themselves . . . they're moving around. That's good news.”

Brunner, for her part, is more determined than ever to show how crucial Font Hill is for songbirds—and figure out how it fits into the Kirtland's success story.