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Open Mic: The Fine Weirdness of the Dry Tortugas

At the Mic: Mark Hedden

The thing no one tells you about the Dry Tortugas: It’s kind of weird to bird there.

The Tortugas are a small cluster of islands 70 miles west of Key West. They are largely made up of broken coral and sand, and they tend to grow and shrink and sometimes disappear at the will of the tides and the storms. When you come back after a few months it can be unsettling, like discovering someone’s rearranged your furniture in the middle of the night.

The largest of the islands is Garden Key, and when John James Audubon visited in 1832 it had more trees and shrubs than the other islands, but not much else by way of hardscape. In the run-up to the Civil War, in an attempt to control shipping traffic in the Gulf of Mexico, the U.S. Government built Fort Jefferson on Garden Key. The effort took thirty years and 16 million bricks –  all of them hauled down from New England or Pensacola, all of them laid by people wearing wool uniforms in the tropical sun.

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Construction was ultimately abandoned before the fort was completed because the project became technically obsolete.

What’s left is a three-story hexagonal behemoth surrounded by aqua blue ocean in the middle of nowhere. The Dry Tortugas became a national park in 1992. Standing on the fort’s parade grounds inside the brick walls is like standing in the middle of a combination football stadium/time machine, an effect that isn’t diminished by the occasional sightings of park staffers dressed in brass button uniforms, hoop skirts, and other Civil War-era garb.

The surreality of the situation tends to fade to the background, though, as you start to clue in on the birds.
While not taxonomically valid, birds at the Dry Tortugas can roughly be divided into two categories – locals and migrants.

The most visible of the locals are the Magnificent Frigatebirds. The species’ only breeding colony in the ABA Area is on Long Key – across a shallow anchorage from the fort. There tend to be about a hundred frigatebirds in the air in the area at a time. Mostly they hang on their 7-foot wingspans and ride updrafts from the fort’s walls, or spin slowly on thermals, but occasionally they squabble with one another, or take off to chase a Royal Terns, trying to bully them into giving up their lunch.

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The other year-rounders at the Tortugas are the Masked Boobies. There are about 75 of them, roosting and nesting on Hospital Key, a small, wave-beaten hump of sand about a mile and a half from the fort. At one time the island was big enough to house a small hospital (yellow fever patients from the fort were quarantined there in the Civil War era), but it is now less than a half-acre in size, sometimes with a small salt pond in the middle. The boobies tend to space themselves across it, like randomly placed bowling pins. At least until they turn into the wind, run those first few awkward steps, leap up, and slice through the air on their mysterious, days-long foraging runs.

Brown Boobies don’t breed at the fort, but there are always a few around. Occasionally you see them flying, but most often you spot them perched in ones and twos on the channel markers surrounding the fort.

The most numerous of the local birds are the Sooty Terns, with their Oreo-crisp black and white plumage, and the Brown Noddies, who are more of a root beer brown. They are not full time residents – the Sooty Terns migrate to the southern Atlantic; the Brown Noddies disappear to parts unknown – but they are the most abundant birds in the park from February to July every year.

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An estimated 80,000 Sooty Terns, with an additional estimated 4,500 Brown Noddies, nest on Bush Key, a 29-acre cactus-and-sea lavender-covered island adjacent to Garden Key and the fort. It is crowded, and at first it can seem chaotic, but there are always several thousand birds in the immediate airspace over the island, and at some point you realize that if is was true chaos, the birds would crash into each other. And somehow they don’t.

It is exceptionally loud, though. Sooties have a fast, annunciated, three-syllable call that, according to lore, and with enough imagination, sound like someone yelling “Wide awake!” That many birds yelling “Wide Awake!” over and over again creates a bit of a cacophony.

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Most birders visit the Tortugas in spring, though, because all this is there, but also because it can be one of the world’s great migrant traps. “Trap” may not be the best word. From the migrating bird’s perspective it is a refuge, maybe even a lifeline. If they are flying from Cuba, it is the only bit of land after crossing 70 miles of open ocean. If they are flying from the Yucatan, and are pushed by westerly winds, it is the first bit of land after 400 miles of open ocean. Most of these birds are not equipped to swim, so landing in the ocean has fatal consequences. Warblers, buntings, thrushes, orioles, cuckoos, nightjars, falcons, accipiters, and swallows are seen consistently through the migration season.

The Caribbean subspecies of the Short-eared Owl tends to be seen a few times a year, often in the overgrown foundations of the old barracks. Other rarities recorded from the fort include Black Noddy, Red-footed Booby, White-tailed Tropicbird, White-tipped Dove, Zenaida Dove, and Bahama Swallow.

The thing everyone hopes for, though, is fallout. While it is difficult to predict, if you’re lucky, and you do an overnight trip, there is a decent chance of experiencing it. The thing you dream of is bad weather – rain, wind or both. In the simplest terms: birds flying overhead hit it, look for safety, and land on the islands. Sometimes it is clear cut. You go to bed, it rains in the night, you wake up, and the place is overrun with birds that weren’t there the day before.
Sometimes (especially if there is a strong westerly wind) you start birding in the morning and fallout is not immediately apparent. But as the day goes on you just keep happening upon new birds in the same places, the trees and bushes constantly replenishing themselves.

The most dramatic version of it I have seen was one late-April afternoon, after a slow-ish day of searching for birds in the seagrapes. As the ferry and seaplanes were departing, and the island was left to campers and people overnighting on boats, a wall of black clouds moved across the water towards the fort.

It rained for 20 minutes, then it stopped, and suddenly the place was overrun with thousands of birds. A dozen Yellow-billed Cuckoos in every tree, Cerulean Warblers at your feet, a sky full of various and sundry Swallows, so many Hooded Warblers and American Redstarts and Ovenbirds that it was hard not to think of them as computer generated replicants. It was one of the most overwhelming and mind-boggling and satisfying experiences of my entire life.

So, yes, birding at the Dry Tortugas is kind of weird. But in the best way.

Wanna visit the Dry Tortugas? Come with the ABA in May! For more information see the ABA’s Events homepage.
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Mark Hedden is a birder, writer and photographer who has lived in the Florida Keys long enough to be ruined for the real world. He is a former owner of Caligo Ventures, which specializes in birding trips to South America and the Caribbean, with a focus on the Asa Wright Nature Centre in Trinidad. He has led many trips to the Dry Tortugas and would live there if the rangers would stop telling him he had to go home.