Red knots are one of the longest-distance migrants in the Western Hemisphere. They spend over half of the year migrating back and forth between wintering and breeding areas.
Various methods are used to study shorebirds in New Jersey and along their migration route.
In Delaware Bay, shorebird scientists conduct a number of different research projects to learn as much as they can about shorebirds and other variables affecting their populations. With almost 30 years of data, these scientists are able to determine if species like red knots are still on the decline, and have a means of identifying the cause.
Shorebird scientists have spent the last ten years conducting systematic aerial surveys and ground counts of New Jersey and Delaware shores during peak shorebird numbers. These counts take place simultaneously on every beach on both sides of the Bay, allowing scientists to get an accurate estimate of the total number of shorebirds. This helps identify if population numbers are going up or down over the years.
When the shorebirds stop in Delaware Bay in late May and early June, scientists make regular catches using a method called cannon-netting. A net is carefully fired over a flock of shorebirds, which are then measured and weighed before being released. These measurements help scientists determine the birds’ general health, as well as whether the shorebirds using the Bay are putting on the weight necessary to continue their migration.
Every single bird trapped by the scientists receives a plastic leg flag containing a two- or three-character code. These codes can be read from a distance by observers with telescopes or binoculars. By combining these resightings, the Team can determine where the birds are wintering, migrating and breeding. And anyone along the birds’ flyway can submit a resighting through the website of the Shorebird Project and see more information about where their bird has been.
The newest tool in the scientists’ arsenal is the geolocator. A tiny device weighing less than a tenth of an ounce, geolocators contain sensors that record data such as salinity and light level, and by combining this light information with known shorebird migration routes, scientists can even determine the bird’s location each day to a few miles. After being mounted on the legs of shorebirds, these devices will record up to three years of data. Using geolocators, scientists have been able to determine unprecedented information, from individual birds’ breeding success in the Arctic, to new stopover and wintering sites, and even birds making hundred-mile detours around hurricanes in the middle of the Atlantic.
Horseshoe Crab Egg Density
The decline in shorebird numbers in the 1990s was sparked by the drastic reduction in the number of horseshoe crabs and their eggs. Since 2005, scientists have taken samples of sand from in New Jersey and Delaware to determine the number of horseshoe crab eggs close enough to the surface for shorebird consumption. This data gives an accurate picture of feeding conditions on the Bay for shorebirds – and an idea of how likely they are to recover.
Because shorebirds don’t only spend their time in Delaware Bay, shorebird scientists must study them throughout the Atlantic Flyway to get the best understanding of their unique ecology. With research locations ranging from the southern tip of Argentina in Tierra del Fuego to the northern ends of Canada in the Arctic province of Nunavut, shorebird scientists travel to the ends of the globe to study red knots and other shorebirds.
To read about the shorebird research team’s latest Arctic expedition, check out the following blogs:
Meet the Project Team
Every year, a team of scientists from around the world gathers in Delaware Bay to conduct research on endangered shorebirds. Together, they have collected almost 30 years of data, documenting the declining population trends of the red knot and other shorebird species.
Report a sighting
Report a sighting of a banded shorebird or rare species.