It is dawn near the mouth of the Pacora River in Panama and the shorebirds are beginning to break from their night roost on an offshore bar. They move out over the water in dozens of flocks, merging and splitting, folding and undulating, to make abstract sculptures between water and sky. The performance continues for more than an hour with flocks alternating between the stage and short respites along the shoreline.
Pacora is shorebird central for 30 kilometers of coast where sand washed from the river has formed a wide delta that includes high, isolated sandbars. Once a month, as the tide reaches above 17 feet, submerging all lower bars, the birds converge here where the high bars provide protection from predators and disturbance as they wait for the tide to retreat. On this day, the roost contains some 300,000 shorebirds—mostly western sandpiper, semipalmated sandpiper and semipalmated plover. Nearly 10 percent of the global population of western sandpipers might be in front of us, in this single roost.
Pacora is a bone-jarring, hour-long journey from the nearest paved road. We have been here all night, listening to the cacophony of roosting birds just offshore and setting up nets to catch them with the changing tide. I’m here with Bart Paxton and Fletcher Smith from the Center for Conservation Biology (CCB). Joining us to study the birds are Rosabel Miro, Yenifer Diaz and Michelle Caballero from the Panama Audubon Society. A collaboration between the National Audubon Society, Panama Audubon Society and CCB, the project’s focus is to establish a marking program in Central America for these birds and to train local biologists in banding techniques.
A critical area for shorebirds
The upper Bay of Panama appears to have been designed for shorebirds. Standing shoulder to shoulder with the Copper River Delta in Alaska, the Amazon Delta in Brazil, and the Bay of Fundy in Nova Scotia, the site is among the great shorebird conservation areas of the Western Hemisphere. My CCB team has worked here off-and-on for more than 15 years to document the number of birds and to understand what role the location plays in their annual life cycle. The site is a critical staging area during migration and a fall molting ground. Most importantly, the upper Bay of Panama is their winter home.
Consistent with protocol over the previous several nights, we store captured birds in holding boxes and bring them to a central banding table for processing. Panama Audubon staff, local university students, local volunteers and a biologist from Nicaragua take turns learning to identify, age, measure, weigh and band the shorebirds. Bart, Fletcher and I give instruction and demonstrations on banding techniques. It’s an important set of skills to teach: For Panama to truly embrace its critical role in the living network of sites, we must have locally-based teams directly involved in research. Field techniques are foundational to the emerging research community throughout Central America.
Before release, birds are fitted with coded leg flags that allow for the identification of each individual. Resighting of these flags throughout the Pacific Flyway will help us to better document migration pathways and contribute to our broader understanding of the demography that underlies population trends. Until you get the hang of it, identifying an individual bird from fleeting glimpses of leg flags can be tricky. We wanted to leave our Panama volunteers with the confidence to sight and record the birds we’ve flagged, so our CCB team provided a workshop on resighting techniques to university students and the local birding community. It was a great day for it: International Wetland Day.
An international committee assigns flag colors to regions and countries throughout the Western Hemisphere. Central America has been assigned a gray flag with black characters. The banding effort in Panama is the first to deploy such leg flags in Central America.
Feeding up on the fertile mudflats
Winter represents the longest period during the annual cycle when these shorebirds remain in one place, and that place is here. As the morning wears on and the tide begins to recede, the shorebirds cover the mudflats and begin to feed. The rich marine resources within these flats are the reason that the birds are here. They are the unique contribution that Panama makes to these populations. These resources forever link this winter site in Panama to the breeding grounds in Alaska and migratory staging grounds in between. But it is the birds that are the common bond that links these places together and it is the birds that bring us all here to collaborate for their future.
Bryan Watts is director of the Center for Conservation Biology, a joint initiative of William & Mary and Virginia Commonwealth University. Watch videos of the Pacora shorebirds.