Audubon Florida News

American Oystercatchers Return to Gulf Coast Via Detour Through NE Florida

posted on October 10, 2014 in Birding,Northeast Florida,Wildlife

Pat and Doris Leary are avid birdwatchers and citizen scientists from Fernandina Beach, FL, who volunteer their time and substantial skills to survey coastal waterbirds in Northeast Florida, coastal Georgia and Florida’s Big Bend. This is the seventh blog in which they share their experiences and sightings as well as the challenges these increasingly imperiled birds face.

Two American Oystercatchers from North Carolina on their way to the Gulf CoastEvery fall we look forward to resuming our annual surveys of American Oystercatchers wintering along the “Nature Coast” and each season finds new birds venturing south on their first migration along with veterans of many years returning to their favored locations from Horseshoe Beach in Dixie County to the power plant jetty just south of the Barge Canal spoils in Citrus County.

On rare occasions, we will encounter birds of that population in northeast Florida. Such an event occurred October 1st in lower Nassau Sound during a routine shorebird survey. Approaching a favored roost site for local Oystercatchers and other coastal species, I noted two birds resting near a flock of migrant Caspian Terns. Presuming these to be “resident” birds, my first binocular view brought quite a surprise: both birds carried dark green bands with alpha codes! With multiple Bald Eagles and Peregrine Falcons present in the sound I rushed to set up a tripod and mount my scope to read the bands. Experience has taught us that marked birds can flush and fly over the horizon in minutes taking all valuable data with them, and  a flying Peregrine Falcon at any distance can compel birds to flush without warning and abandon a site.  Fortunately, no raptors appeared and the resting birds provided ample time to study their bands and record the codes.

I immediately knew that both birds originated from North Carolina, but we have recorded far too many band codes to recognize a previously sighted bird and I would have to wait until I returned home to search our records before confirming any resights. Doing so, I learned that one bird (EO) was indeed a winter veteran recorded on the gulf every year since 2007. The second bird (UT) was more problematic. Banded at North Core Banks, Cape Lookout, NC in 2010 UT had been resighted there multiple times but nowhere else. However, Doris reminded me that each season we record a few “problem” codes that cannot be matched in the database. Typically, this is attributable to misread codes, data entry typos or incorrectly recorded codes. The original “wrap around” alpha codes have always presented a challenge to read and record correctly due to partial exposure of one or the other letter. Depending on distance, wind vibrating optics, ambient light, flock density, vantage point and other factors, Xs can resemble Ks, Fs with Rs, Ps with Rs, Os with Js, Js with Us and so on. Often, even photos cannot resolve a “suspect code” if only a partial letter is exposed. Such factors may have contributed to our lack of records for the UT bird on the gulf coast. It’s possible the bird was present for one or more years, but due to our failure to correctly read and report its bands, the sighting could not be entered into the database.

The fact that the two North Carolina birds were together certainly suggest they will eventually cross over to the gulf coast and join the wintering flocks there. Given the mystery of the UT bird, it will certainly be on our radar as we resume our gulf surveys and hopefully we can confirm its presence there soon. Some might recall that bird DG[CF6] with satellite transmitter was tracked from North Carolina to the vicinity of Amelia Island last fall before turning and crossing over to the gulf toward Horseshoe Beach. Later that winter, the bird shed its transmitter but was resighted prior to spring migration. Perhaps we’ll cross paths with that bird too sometime during the next several months.

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