TRACKING THEIR PATH AS THEY HEAD SOUTH FOR THE WINTER
By Allison Anholt, Field Technician, (NJDFW) and Emily Heiser, Field Technician, (CWFNJ)
Throughout the fall, there is a remarkable sight to see along New Jersey’s coastline. Thousands of shorebirds group together in huge flocks, using our state’s coastline as a migration stopover point to rest and feed. One particularly interesting shorebird is the American oystercatcher, which is listed as a species of special concern in New Jersey. At the Conserve Wildlife Foundation of New Jersey, we work with biologists from the New Jersey Division of Fish and Wildlife to survey these birds throughout the fall season.
The oystercatcher is an especially easy bird to survey during fall migration due to its distinct features. Not only do they stand apart from other shorebird species with their unique orange bill and striking coloration, but color bands help us determine individuals as well. Banding efforts have been underway in New Jersey since 2004 in order to give insight to researchers regarding the
oystercatcher’s breeding habits, pair behavior, and migration patterns. About 300 oystercatchers have been banded in New Jersey to date, including a significant percentage of the state’s estimated 400 breeding pairs.
Adult oystercatchers are captured every year during their breeding season using a trap called a noose carpet. This flat trap, which is covered in noose knots, is partially buried under the sand near the oystercatcher’s nest. A wooden decoy is placed in the middle of the trap. When the breeding pair catches sight of the decoy imposter, they approach it to defend their territory and get caught in the trap. Once trapped, researchers place two orange bands with a two letter/digit code, denoting that they were caught in New Jersey, and one silver U.S. Fish and Wildlife Service band on their legs. They also take a variety of body measurements and obtain a DNA sample from a feather for further research. Chicks are also banded a few weeks after hatching and before they are able to fly.
The process of banding oystercatchers, while time consuming, has taught us many important things. Among many other findings, banded birds have helped us confirm that oystercatchers are long living, and exhibit strong site fidelity and pair bonds. Individual color bands have also shown us their migration route, as well as how long they stay at their migration stopover sites and wintering grounds.
In order to protect the population of oystercatchers, a partnership based organization called the American Oystercatcher Working Group meets annually to discuss implementing effective research and management along the Atlantic and Gulf Coasts. Supporting range wide management of oystercatchers, the group looks at not only local trends but assesses the population’s range wide success as well. As mentioned above, one of the major components to oystercatcher monitoring is the orange bands New Jersey uses as a tool to look at a variety of things from breeding behavior to migratory movements. Many coastal states have taken an initiative to band a certain percentage of their oystercatcher population during the breeding or wintering season. Each state involved is given a color and each band is individual specific with an alpha-numeric code. Massachusetts has yellow bands, Delaware green flags, Virginia black bands, North Carolina green bands, South Carolina dark blue bands, Georgia red bands and the Gulf population in Texas is banded with maroon bands. When a banded oystercatcher is reported, we can then identify and trace the exact origin of that bird.
As oystercatchers are now entering the fall months, their primary goal is to boost their fat and energy reserves for migration and the long winter months. The distribution of oystercatchers during migration varies from state to state. From resighting those individualized color bands, we can see where the birds are moving to, and generally speaking where they will spend most of the winter. Since banding oystercatchers began in the early 2000’s, many of the bands have been resighted during wintering months. According to wintering surveys conducted from 2006-2008, a roost of ~1200 oystercatchers annually winters on Florida’s upper Gulf coast (centered near Cedar Key). A high percentage of the banded birds reported were migrants from the northeast region (MA, NJ, VA).
Many of us dub the closing of the summer months and the beginning of fall as the “off-season” here at the Jersey Shore. We would also consider this the “off-season” for beachnesting birds as they make their way south for the winter. However, it is important to remember the challenges that not only oystercatchers, but thousands of other shorebirds face in the upcoming wintering months. Their wintering habitat is perhaps just as important to protect as their breeding habitat. Those colorful plastic bands we’ve been mentioning have helped researchers see that our oystercatcher friends don’t enjoy as much of an “offseason” as we do.