Dry Tortugas Apr 30—May 03, 2009
Posted by Brennan Mulrooney
Dry Tortugas National Park is unique. Cliché? Maybe. Accurate? Absolutely! The park contains the only breeding colonies of Masked Booby, Magnificent Frigatebird, Sooty Tern, and Brown Noddy in North America. It is home to historic Fort Jefferson, the largest masonry structure in the Western Hemisphere. Every spring, scores of migrant birds stop to rest there, affording birders unmatched opportunities for close study and photography. In addition to all that, it is only reachable by boat or seaplane, so we basically have this incredible area to ourselves each morning and evening of our stay. This year's trip to Dry Tortugas had everything one could hope for: exciting pelagic birds and sea life on our crossing to the island, the awesome spectacle of breeding terns on Bush Key, a staked-out rarity, and a great assortment of migrants.
Strong winds made pelagic birding a bit of a challenge, but we did well with our main targets and had a bonus rarity to boot. While Sooty Terns breed by the tens of thousands on Bush Key, the similar Bridled Tern can only be expected on the crossing in deep water. Our first few sightings left much to be desired, but eventually we found two sitting on the water that gave us fantastic views and even called for us. We were also treated to a great show of feeding Northern Gannets that were joined by a Brown Booby, providing nice comparisons of the immature plumages of both species. The surprise of the trip was a juvenile tropicbird that gave us a distant fly-by, but we were unable to chase it due to the rough weather. White-tailed is the more common (though still rare) species in this area, but this bird looked more like a Red-billed Tropicbird. Unfortunately it never gave us a good enough view to be sure. Whichever species it was, it certainly gave us a thrill, and the brief chase gave us a refreshing shower.
Each morning we woke to the incredible sight and sound of tens of thousands of Sooty Terns and Brown Noddies in a cloud over Bush Key where they nest. In the evenings we took rides in the skiff out to Bush and Long Keys to get closer looks at the nesting terns, as well as the colony of Magnificent Frigatebirds. In the frigatebird colony we enjoyed views of big, gangly, down-covered chicks, as well as adult males with their huge red gular pouches inflated in courtship display. Several groups were treated to views of small loggerhead turtles and huge nurse sharks on these skiff trips.
In our time on Garden Key we turned up a nice variety of migrant birds. Our 12 species of warblers included Black-throated Blue, Cape May, Magnolia, Ovenbird, Blackpoll, and Hooded among others. A flock of Indigo Buntings that included several stunning males provided wonderful photographic opportunities. A pair of Orchard Orioles fed in flowering sea grape trees, while two very sneaky Yellow-billed Cuckoos ran us in circles inside the fort. Perhaps our most unexpected migrant was a Glossy Ibis that obviously was not happy to be there, but was equally unhappy about the prospect of leaving sight of land.
One of the main draws of a trip to the Dry Tortugas is the chance to see a rarity. Isolated pockets of habitat, like a grove of trees in the desert, or a vegetated island in the ocean, will concentrate wandering birds, and regular checks of these concentration points is how vagrant birds are often found. Dry Tortugas is famous for this, and we benefited from previous birders' efforts by finding a Black Noddy that had been roosting on Bush Key among hundreds of Sooty Terns and Brown Noddies. If we hadn't known right where to look, we would have had a very difficult time seeing this bird, but we all got scope views of this rare visitor.
As we cruised home on our last day, I was already thinking about the next time I would have the opportunity to visit this special destination. I wondered what surprises would be found that time, and then (surprise!) we found a channel buoy that had about 10 Roseate Terns perched on it. This was a life bird for most of the group, and it was a fantastic way to end a magical trip.