Traffic On the Atlantic Flyway
A record-breaking number of Ospreys have been sighted in the Florida Keys this season. Here's why.
A heavy squall had just brushed past the Florida Keys, the deluge fading into a drizzle. Rafael Gálvez and his fellow hawk watchers emerged from their station, only to be hit by another storm. This one was less rain and more feathers. An army of Ospreys, blown off course by a gale from the east, was hurtling by overhead.
The five counters were unfazed. Like stockbrokers on the trading floor, they shouted out numbers from opposite ends of the platform. To some it may have seemed like chaos. But to professionals like Gálvez, the director of the Hawkwatch, there was some method to the madness. Once the hour-long frenzy had subsided the final tally read 301 Ospreys—that's an average of one Osprey every 12 seconds. Never in the history of the Florida Keys Hawkwatch had there been such a phenomenon.
Gálvez wrote about the Sept. 25 spectacle on the Florida Keys Hawkwatch blog: "Rain continued for nearly an hour. What followed was a low flying 'mat' of back-to-back Ospreys in slow flight over the trajectory of the Keys' island chain, towards the SSW. At times, dozens of Ospreys could be seen simultaneously SW and away from our count site. The horizon was dotted with them; at one point I counted about 35 Ospreys in a single binocular view. By the time that hour was over, we had tallied 301, bringing our day's total for that species to 394, and shattering the previous single-day high count of 340 from 2003!"
Gálvez credits the storm for herding the Ospreys close to the shoreline. The eastern winds and the slanting rain created a bottleneck for the birds, putting them directly in the sight line of the Hawkwatch. "It's not that large numbers of Ospreys aren't out there," says Gálvez. "We just don't see them over land." While the birds had to take a bit of a detour, Gálvez doesn't think that the extra mileage will have a negative impact on their migration. Ospreys are accustomed to wily ocean conditions. They're also very strong fliers; the 90 miles between the Keys and Cuba is equivalent to a short sprint for them.
Most of the raptors seen in the Keys are either headed to Cuba or the crown of South America. And though they're often seen in flocks, these birds aren't interacting with one another. Instead, they're all taking advantage of the same wind patterns. Islands like the Florida Keys create columns of hot air. The rising air attracts birds, both flocks and loners, who use it as a flyway to get to their destination. "We perceive them as together," says Gálvez. "But the truth is, they're just a circumstantial group of individuals, riding the same highway, hoping to make it through another long migration."