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Introduction
This Recovery Plan aims to restore the Red Knot Rufa from its status of being Near
threatened to a point where the population will be at a much-sustained level. There are
approximately 42,000 birds alive and active as of 2019. The population of the Red Knot Rufa is
this low for a variety of reasons, such as climate change, habitat disturbances, and the
overharvesting of horseshoe crabs. The goal of this recovery plan is to combat these damages to
the Red Knot Rufa population and restore it to where it was prior to the 1980s where it dropped
more than 50%.1
Taxonomy
The Taxonomy of Red Knot Rufa is as follows: Class: Aves. Order: Charadriiformes.
1 Cornell University. (2014). Red Knot Life History, all about birds, Cornell Lab of Ornithology.
All About Birds, Cornell Lab of Ornithology.
https://www.allaboutbirds.org/guide/Red_Knot/lifehistory
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Family: Scolopacidae. Genus and Species: Calidris canutus rufa.2
The Red Knot Rufa (Calidris canutus rufa) is a shorebird that has a round body, long legs,
a small head, and small eyes. The beak narrows out and is slightly longer than the head. The
males weigh on average 115.7 grams and have a brighter colored face and chest than the females.
The females weigh on average 124.2 grams and have a longer beak than the males. Both sexes
average out at 27 cm in length. The Rufa’s breeding plumage is the dullest compared to the rest
of the red knot species. In the breeding season, they are reddish brown and this color is seen on
the face, chest, and belly. The head is dark gray while the eye strip and back tail are a rust color
and the rear belly is white. The feathers are gray with white edges and the center of the feathers
are rust colored. When not in the breeding season the head, tail, and back are a plain gray and the
eye strip turns white. The face, belly, and chest are off-colored white. The upper chest may have
dark streaks that extend down the sides.3
US and Virginia Distribution
The Red Knot Rufa is found in the United States during migration. They are most
commonly found in the Delaware Bay. They also appear on the coastlines of New York, New
Jersey, Maine, Massachusetts, North Carolina, South Carolina, Florida, Georgia, and Virginia.
They are found on the coastlines and beaches. They also appear in several states in the Midwest.
In Virginia, they are found in the coastal plain region of the state.
2 Rufa Red Knot (Calidris canutus rufa): U.S. Fish & Wildlife Service. FWS.gov. (n.d.).
https://www.fws.gov/species/rufa-red-knot-calidris-canutus-rufa
3 Avery, J. (2011). Calidris canutus rufa. Animal Diversity Web.
https://animaldiversity.org/accounts/Calidris_canutus_rufa/
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Range of the Red Knot Rufa 2
Natural History
The Red Knot Rufa has an average life span of 7 years in the wild, with the highest being
reported as 16 years of age. Both males and females become sexually mature at 1 to 2 years of
age. The Red Knot Rufa breed between late May and early June. These birds are monogamous
however they may keep the same partners for years at a time, they can also only have seasonal
partners as well. Mating is initiated by the male who follows the female while raising his tail in
display and pecking at her back. If the female reciprocates, the male will mount and the female
will reveal her rump. The two will then make cloacal contact which lasts roughly a minute. The
male will then fall and lower himself and hold onto the female's head, neck, and nape feathers
with his beak for a few seconds. This interaction will occur many times a day during the
breeding season.
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The breeding grounds are located north of Canada in the Arctic Region. The pair will
average about 3 to 4 eggs per season and these eggs take approximately 22 days to hatch. Both
parents participate in incubation, if the eggs are lost the pair will not replace it. When the chicks
are hatched they weigh roughly 5.5 ounces. After they hatch, the mother abandons the group and
the father becomes the sole protector. The father will defend and protect the young but will not
feed them, instead the Red Knots forage from birth. The father will stop protecting the chicks
when they fledge between 18 to 25 days. There are no distinctions between male and female
juveniles. They both have a dark gray head with a white eye stripe. The body is primarily gray
with white edges on the feathers and has a white belly and chest.
Red Knot Rufas are omnivores but are primarily carnivores. Their preferred prey is
horseshoe crab eggs. They also consume small mollusks and mussels, insects, and some other
plant life.
In the United States, when they migrate for the winter their primary predators are
peregrine falcons, harriers, and short-eared owls. While they are on breeding grounds, their
predators are Arctic Foxes, Herring Gulls, and Long-Tailed Jaegers.
The Rufas are primarily active during the day and evening and can often be found
foraging. They are not found often during the night. However, they will migrate day and night.
Red Knot nest in High Arctic environments, such as the arctic portions of Canada. They can be
found in dry tundra slopes, far from the coast but on warmer slopes facing the south. They move
to feed in wetter habitats. When the young begin to fly, they move to sedge meadows and shores
of lakes to feed. When they migrate, they can be found in warm marine habitats, such as lagoons,
swamps, beaches, and mud flats.1 They have an estimated population density of 42,000. Almost
90% of the population can be found on the beaches during migration.2
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The International Union for Conservation of Nature Red Lists lists the Red Knot Rufa as
Near Threatened. This is the same for the national level as well as Virginia.1
Many things threaten the Red Knot Rufa population. These include things such as climate
control, in particular the melting and shrinking of the tundra, rising ocean levels, the ocean
becoming more acidic, and worsening weather that would disrupt their migration. The largest
and most damaging threat to the Rufas is humans. Due to the overharvesting of horseshoe crabs
in Delaware Bay, there are not enough horseshoe crab eggs laid,4 which is the Rufa’s main source
of food and energy during their migration period. Rufas are also hunted for sport in other parts of
the world but this practice has become outlawed due to their endangered status.
Conservation Plan
There are several ways to combat the loss of habitats due to Climate Control. First is to
begin protecting their winter habitats and begin surveying and tracking the birds that come into
that area. It would work well to create a network of winter habitats so it can be more accurately
observed and be able to track with greater precision. It would also be beneficial to do the same
with migrating and stopping points of the birds. Next would be to begin developing new habitats
that would be protected and heavily monitored so the birds have areas away from threats.
While laws have been passed and the overharvesting of horseshoe crabs in Delaware Bay has
lessened in recent years, there are still not enough eggs being laid to feed the Rufas. Further
action is required against the biomedical companies who harvest horseshoe crabs for their blood
4 KARPANTY, S. M., FRASER, J. D., BERKSON, J., NILES, L. J., DEY, A., & SMITH, E. P.
(2006). Horseshoe crab eggs determine red knot distribution in Delaware Bay. Journal of
Wildlife Management, 70(6), 1704–1710. https://doi.org/10.2193/0022-
541x(2006)70[1704:hcedrk]2.0.co;2
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which is useful to detect toxins. As well as fisheries who use the crabs as bait.5 The horseshoe
crab has been over-harvested to near extinction along the East Coast and endangered in New
England, if the horseshoe crabs go extinct,6 the Red Knot species would follow shortly after.
There have been groups that go out in the early mornings to scour the beach for washed-up
horseshoe crabs, most of the time these crabs have been flipped over and can not get back in the
water. These groups go out and flip the crabs back upright so they can return to the ocean. It
would be incredibly beneficial to create more hatcheries for the Horseshoe Crabs and create
more protected and observed habitats for them. Unfortunately, other countries do not have
protection laws for the Red Knot Rufa as the United States does, so there is little to be done
about the birds being hunted in other countries.
5 Center for Biological Diversity. (2023, October 19). Female Horseshoe Crabs spared for another year in
Delaware Bay. https://biologicaldiversity.org/w/news/press-releases/female-horseshoe-crabs-spared-for-
another-year-in-delaware-bay-2023-10-19/#:~:text=Horseshoe%20crab%20populations%20have
%20crashed,remain%20at%20historically%20low%20levels.
6 Horseshoe Crab. Defenders of Wildlife. (n.d.). https://defenders.org/wildlife/horseshoe-
crab#:~:text=Overharvest%20and%20exploitation%20by%20the,blue%20blood%20for%20biomedical
%20purposes.
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Citations
●Avery, J. (2011). Calidris canutus rufa. Animal Diversity Web.
https://animaldiversity.org/accounts/Calidris_canutus_rufa/
● Center for Biological Diversity. (2023, October 19). Female Horseshoe Crabs spared for
another year in Delaware Bay. https://biologicaldiversity.org/w/news/press-
releases/female-horseshoe-crabs-spared-for-another-year-in-delaware-bay-2023-10-
19/#:~:text=Horseshoe%20crab%20populations%20have%20crashed,remain%20at
%20historically%20low%20levels.
●Cornell University. (2014). Red Knot Life History, all about birds, Cornell Lab of
Ornithology. All About Birds, Cornell Lab of Ornithology.
https://www.allaboutbirds.org/guide/Red_Knot/lifehistory
●Horseshoe Crab. Defenders of Wildlife. (n.d.). https://defenders.org/wildlife/horseshoe-
crab#:~:text=Overharvest%20and%20exploitation%20by%20the,blue%20blood%20for
%20biomedical%20purposes.
● KARPANTY, S. M., FRASER, J. D., BERKSON, J., NILES, L. J., DEY, A., & SMITH,
E. P. (2006). Horseshoe crab eggs determine red knot distribution in Delaware Bay.
Journal of Wildlife Management, 70(6), 1704–1710. https://doi.org/10.2193/0022-
541x(2006)70[1704:hcedrk]2.0.co;2
●Rufa Red Knot (Calidris canutus rufa): U.S. Fish & Wildlife Service. FWS.gov. (n.d.).
https://www.fws.gov/species/rufa-red-knot-calidris-canutus-rufa
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