The red knot is a medium-sized shorebird that makes one of the longest migrations known in the animal kingdom. Each year, some red knots fly more than 9,000 miles from their wintering grounds at the southern tip of South America to their breeding grounds in the Arctic. Along the way, they stop at key staging and stopover locations to rest and feed in preparation for the next leg of their journey. One of the most important stopovers for red knots in eastern North America is Delaware Bay, where the birds refuel on horseshoe crab eggs to build up fat reserves for the final push to the Arctic. However, in recent decades, the red knot population has plummeted by nearly 75% in some areas, leading to the species being designated as threatened under the Endangered Species Act in 2015. A major factor in this decline has been the overharvesting of horseshoe crabs in Delaware Bay, drastically reducing the vital food source that red knots rely on. The red knot recovery plan aims to stabilize and restore red knot populations by protecting and managing their habitat, especially horseshoe crab populations in Delaware Bay.
Background on the Red Knot Decline
During their spring migration north, red knots time their arrival at Delaware Bay to coincide with the spawning season of horseshoe crabs. For about two weeks from mid-May to early June, the birds gorge themselves on the nutrient-rich horseshoe crab eggs in the bay beaches to quickly gain weight before flying thousands more miles to their Arctic breeding grounds. However, in the 1990s, overharvesting of horseshoe crabs for use as eel and whelk bait caused a sharp decline in crab populations and a drastic 90% drop in egg numbers. Without enough horseshoe crab eggs, red knots could not consume enough to successfully complete their migration and breeding. Studies found that red knots arriving at Delaware Bay had about half the body weight they did in the 1980s. With inadequate fat stores, many knots likely died during migration or failed to breed upon reaching the Arctic. Researchers estimate that in 2003, about 50% of the red knot population that stopped in Delaware Bay failed to make it to the Arctic to nest. This precipitous decline spelled disaster for an epic migratory bird already facing threats from climate change, habitat loss, and disturbance.
Initial Conservation Actions
In response to the crisis, initial conservation actions focused on reducing horseshoe crab harvests and protecting important red knot habitat in Delaware Bay. In 1998, the Atlantic States Marine Fisheries Commission implemented a horseshoe crab harvest quota system for states across the knot’s migratory range. New Jersey instituted a moratorium on horseshoe crab harvesting in 2008 followed by Delaware in 2013. These actions allowed some recovery of crab populations and eggs, although not enough to support substantial increases in red knot numbers. Since 2003, New Jersey, Delaware, and other partners have also worked to restore 50 acres of critical knot stopover habitat in Delaware Bay. Conservation groups purchased undeveloped beach properties for protection and removal of invasive plants like phragmites. With more suitable habitat, red knots could better rest and fatten up during their brief Delaware Bay stopovers.
Path Forward to Recovery
While the initial actions helped slow or halt the decline, red knot populations remained dangerously low. More intensive efforts would be needed to rebuild numbers enough to allow delisting under the Endangered Species Act. When the red knot was federally listed as threatened in 2015, the U.S. Fish and Wildlife Service also designated 70,000 acres of coastal habitat in New Jersey and Delaware as critical for the species’ survival and recovery. This underscored the importance of habitat protection. The listing decision also required the development of a formal recovery plan to guide actions to achieve population targets and address primary threats. The draft recovery plan was released in 2019 following extensive input from federal agencies, coastal states, tribes, industry representatives, scientists, and conservation groups.
Recovery Goals
The overarching goal is to reach red knot population targets that represent secure levels the species can sustain into the future even with threats like continued habitat loss. The plan outlines two key objectives needed to achieve this goal:
- Attain self-sustaining red knot populations with specific targets for each of the three subspecies in North America. For the threatened rufa subspecies that migrates to Delaware Bay, the target is 100,000 birds including 50,000 counted during spring migration stopovers.
- Implement conservation actions to address ongoing threats like habitat degradation, reduced food availability, and disturbance to wintering and migratory habitats across the knot’s range from the Canadian Arctic to South America.
Major Recovery Actions
To meet the goals and objectives, the draft plan identifies key recovery actions in four main categories:
- Reduce Threats and Improve Habitat Quality – Actions aim to lower impacts from shoreline development, beach erosion, human disturbance, predation, and inadequate food supplies at migration stopovers and wintering areas. Efforts will focus on preserving high-quality habitats through acquisition, easements, or regulations. Additional habitat restoration and management activities are recommended.
- Monitor Red Knot Populations and Habitats – Continue annual surveys at wintering areas and Delaware Bay to closely track red knot numbers and habitat conditions. Also increase monitoring at other lesser-known stopovers to fill information gaps.
- Increase Public Awareness and Partnerships – Expand education programs, signage, andother outreach to raise public understanding of threats knots face and build support for conservation actions on public and private lands.
- Adaptive Management – Review new information from enhanced monitoring to adapt and improve recovery efforts. Plan updates will support this adaptive management approach.
Key Habitat Sites for Protection and Management
The recovery plan calls out priority wintering, migration stopover, and breeding sites across the red knot’s range needing focused habitat protection and management. Top priority locations in the United States include:
- Delaware Bay – Continued crab harvest restrictions and habitat restoration here are vital to support adequate food resources for migrating knots.
- Virginia Barrier Islands – Provide critical first mainland stopovers for knots after long overwater crossings from wintering areas.
- North Carolina Winter Sites – Major wintering areas that host up to 75% of the rufa red knot subspecies population from December to February.
- Texas Gulf Coast – Also important wintering grounds with extensive tidal flats for foraging.
Internationally, key sites occur along the north coast of South America and at Arctic breeding locations in northern Canada and Alaska. Ongoing work with partners in other countries will be needed to conserve red knot habitats throughout their range.
Recovery Criteria
Delisting of the red knot from threatened status would first require meeting the population targets through actions in the recovery plan. Additionally, specific criteria must be met regarding ongoing threats and habitat conditions:
- Sufficient high quality habitat is protected and managed to support the increased red knot populations at Delaware Bay and other sites.
- Horseshoe crab harvest restrictions are adequate to maintain egg densities needed to support migrating knots.
- Disturbance levels are controlled at critical wintering and stopover habitats.
- Monitoring demonstrates population targets have been met for at least 10 years indicating stable or increasing trends.
If the recovery plan goals are achieved and criteria met, the Fish and Wildlife Service could propose delisting the red knot. Even if delisted, some protections would remain under the Migratory Bird Treaty Act and continued monitoring and habitat management would be necessary.
Partnerships and Public Involvement
Implementing the comprehensive recovery plan will require coordinated efforts and resources from government agencies, conservation groups, academia, industry, landowners, and other partners over a large geographic area. Partners like the American Littoral Society and Conserve Wildlife Foundation have already made major contributions through habitat restoration and protection at Delaware Bay. Their continued involvement along with new partners will be essential. For recovery actions on private lands like habitat projects, enrolling landowners in voluntary programs is a key approach outlined in the plan. Outreach through birds and nature festivals and programs at wildlife refuges and parks can also engage more public participation. With strong partnerships and support, successful red knot recovery is achievable through diligent implementation of the multifaceted plan.