Less than two decades ago, more than 100,000 red knots filled the skies of Delaware Bay during their epic spring migration from South America to breeding grounds in the Canadian Arctic. Today, fewer than 13,000 of the shorebirds remain, a number that continues to decline steadily.
Why They’re Important
The red knot’s remarkable migration is one of the wonders of the animal world, attracting scientists, birdwatchers and wildlife enthusiasts worldwide. As an indicator species for other Arctic long-distance fliers, the red knot has been subject to extensive research on its breeding behavior, wintering ecology, migration patterns and stopover sites. At peak numbers, the annual stopover of knots at Delaware Bay was a sight to behold.
One of the greatest threats to red knots today is a lack of horseshoe crab eggs to eat at Delaware Bay, a critical stopover and refueling point on the shorebird’s migration. When red knots leave Delaware Bay in poor condition due to the lack of these eggs, which are a protein-rich food source, they either die before ever arriving in the Arctic or arrive in too poor a condition to successfully reproduce.
In the 1990s, overfishing for use as bait caused the horseshoe crab fishery to crash, and as their food source diminished, so did the red knot population. Although horseshoe crab harvests are now limited, too many are still being taken from the ocean and egg densities have not yet rebounded. Now, the harvesting of horseshoe crab blood for biomedical purposes may also be playing a role in slowing the recovery of the Delaware Bay horseshoe crab population.
Climate change is another threat facing red knots. Rising temperatures are changing conditions of the shorebirds’ tundra breeding grounds, as well as habitat at the far south and north ends of their range. Sea level rise also threatens to swallow some of the red knot’s most important habitat and feeding areas.
What Defenders Is Doing to Help Red Knots
Defenders of Wildlife is working to see the red knot listed under the Endangered Species Act (ESA). Since 2005, Defenders has submitted four formal requests to list the shorebird under the ESA to the U.S. Fish and Wildlife Service (FWS). Citing a lack of resources and other priorities, FWS failed to list the red knot but placed it on the candidate list in 2006, where it has continued to languish. In July 2011, FWS announced the decision to speed up the process to formally add the red knot to the list of threatened and endangered species.