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 eighth blog in which they share their experiences and sightings as well as the challenges these increasingly imperiled birds face.
Our first seasonal surveys on the Nature Coast brought a rude and troubling surprise when we visited sites in the Horseshoe Beach area the first week of October. Departing the boat ramp, all appeared normal as we initially ran south to an oyster bar in the open gulf to scan flocks arriving to roost during the high tide period. Though many birds concentrated there, we also observed large numbers roosting on distant bars and, as the tide swelled, those birds flew north to the traditional jetty roost. Given the predicted height of the flood tide, we knew that all birds would eventually shift to the jetty rocks thus we too set off for the distant structure.
Conditions were pleasant as we raced over the shallow gulf waters passing frolicking porpoise, but as we drew near the rocks a pungent smell was evident and, upon landing, we noted numerous fish carcasses rotting in the bright sun. We had never previously encountered such an event on the gulf and speculated on its cause. Later, while scanning the roosting birds from our drifting vessel, we noted an enormous carcass stranded in the jumble of limerock . At distance, the bloated body with projecting pectoral fins resembled a manatee, but closer inspection revealed it to be a Goliath Grouper. This specimen deepened the mystery, for why would a deep water species wash up so close to shore?
Prior to our departure from the jetty and, in a repetition of last season's first survey, a Peregrine Falcon strafed through the panicked mass of birds but quickly vanished through a cloud of "avian confetti" spread across the sky. As we drove out of the tiny hamlet we stopped at a tackle store to seek more insight into the fish kill and learned that it was associated with a red tide impacting the entire region but the details were sketchy. The full extent of the event would not be known until we purchased a regional paper and learned that it covered multiple counties on the upper gulf and was impacting inshore and offshore waters - thus explaining the Goliath Grouper carcass. Upon our return home, an internet search provided even more insight and disclosed the event dated back to July and covered many thousands of square miles in the gulf.
Red tides are rare on Florida's Atlantic coast, but even extreme northeast Florida was impacted several years past with large fish kills washing ashore and noxious vapors irritating beachgoers during periods of onshore winds. Fortunately, that event was restricted to offshore waters, but the impacts were felt on the beach for two weeks or more.
The following day, we surveyed sites on both sides of Cedar Key and found high numbers of American Oystercatchers and other shorebirds present but no signs of the red tide's impact. For unknown reasons, the roosting flocks were unusually nervous, continuously flushing and shifting locations throughout the high tide period. Never previous had we been compelled to move and relocate so often during a day's work. On some occasions soaring Bald Eagles explained the behavior, but at other times no clear threat was evident in the expansive gulf sky, but perhaps one clue was discovered later in the day when we visited one of the oyster reefs and the entire shorebird population exploded into the sky when yet another Peregrine Falcon materialized and casually passed amongst the panicked flocks before moving on.
As often occurs on the gulf, the day began with sunny skies, unpredicted winds and choppy waters that later gave way to overcast skies and dead calm conditions enhancing the region's often tranquil ambiance. By day's end we had recorded dozens of American Oystercatcher band codes, two new Piping Plover flag codes, two Red Knot flag codes and two unusual Wilson's Plovers banding codes. Subsequent to reporting the observation data, we learned that the two Piping Plovers were banded on adjoining alkali lakes near Long Lake National Wildlife Refuge in southwest South Dakota; one as an adult and the other a hatch year chick. Like so many other banded Red Knots recorded on the gulf coast, the two resighted near Cedar Key on this survey were of the population that winters in the southeast and passes through Delaware Bay each spring. One of the birds is now at least eleven years old.
The marked Wilson's Plover is likely a bird resighted in the area last fall, but now wearing new bands replaced for the originals that faded. Such replacements are not unusual for many shorebirds if they are recaptured by researchers in subsequent seasons. For many years, young Piping Plovers returning to the Great Lakes have routinely been recaptured and fitted with new or different markers to identify them as breeding adults. Across their entire range, researchers have experienced problems with band fading and endeavor to recapture such birds to replace them with more durable color bands or coded flags. Because multi color bands are used to uniquely mark individual birds, faded bands defeat their function and make field identification highly problematic even with photographs. Recaptured Red Knots may receive new markers and/or tracking devices depending on location and circumstances.
Unfortunately, many Red Knots banded in Florida now carry flags with faded codes that are impossible to decipher under all but ideal conditions. Faded bands are now occurring amongst the growing research sample of marked Wilson's Plover and are being replaced when possible per the aforementioned bird.
Given the unanticipated winds encountered during our first survey day, we abandoned our plans to travel south to survey the distant barge canal waters and returned to Cedar Key the following day. Not surprisingly, conditions were calmer and we ventured north to a nearby island. There we resighted one of the prior-recorded Piping Plovers and a growing concentration of American Oystercatchers and other species. From that vantage point, we could see another island lying low in the offshore waters and like many landforms along the Nature Coast, that island is now much reduced in dimension since our initial visits just eight years previous.
Formerly, the mangrove islet featured a raised sandy beach and projecting spit that hosted legions of American White Pelicans, Double-crested Cormorants and shorebirds. All that remains today is an ever-shrinking cluster of mangroves. Sandy shores and other loose-sediment structures throughout the Nature Coast are rapidly diminishing and may have long term impacts on shorebird populations, especially their roosting behavior.
Due to the astronomical spring tides impacting the region we visited many traditional roost sites that were submerged on high tide and thus hosted no birds. When recreationist occupy alternative roost sites, the birds are compelled to shift wherever adequate habitat exist to rest during the flood tide periods. Most shorebirds seek low, open and exposed sites away from uplands to roost and such sites are highly sensitive to disturbance and vulnerable to usurpation by recreationists. We often find kayakers, canoeist and motorized vessels landed in such habitats. Protection and conservation of such sites may soon become a management imperative in many coastal areas.
Near the end of the field work, we visited another island just offshore of downtown Cedar Key. On one visit last winter, that sandy habitat supported many hundreds of small shorebirds and one Piping Plover, but on this visit is was entirely underwater and not a single bird was present.
