The Red Knot flies each fall along two crisis-ridden migratory routes. One is the East Asia-Australasia Flyway, where many stops along the way have been damaged due to reclamation and other human activities. The other route, across the United States to a winter destination in Tierra del Fuego at the southern tip of South America, is threatened in part by overharvesting of horseshoe crabs. Here are some fascinating facts about these amazing long-distance flyers, compiled by the Cornell Lab of Ornithology and Chinese experts.
- The Red Knot does not regurgitate undigested hard parts of prey, as do many species of birds. Instead it excretes the hard parts in the feces. Researchers have used fecal content to examine food consumption rates.
- Red Knots concentrate in huge numbers at traditional staging grounds during migration. One of them is the Luannan Wetland, located in China’s Tangshan City, Hebei Province. As the main food of the Red Knot is the smooth blue clams that are abundant there, 80 percent of the birds stop there in the spring to replenish their energy. However, because the surrounding areas of the Luannan Wetland have been reclaimed, the Red Knot is seriously threatened. The protection status of the wetland directly determines whether the Red Knot can successfully reach the its Arctic breeding grounds.
- On the other side of the earth, in the Delaware Bay in the United States, another important staging area during spring migration, where the knots feed on the eggs of spawning horseshoe crabs, is also compromised. It is estimated that nearly 90 percent of the entire population of the Red Knot subspecies C. c. rufa can be present on the bay in a single day. The reduction in food available to the Knots because of the heavy harvesting of horseshoe crabs may be responsible for a decline in Red Knot populations.
- The oldest recorded Red Knot was at least 15 years, 11 months old. It was banded in 1986 in New Jersey and recaptured and rereleased during banding operations in Delaware in 2001.
Eats: Invertebrates, especially bivalves, small snails, and crustaceans. During breeding season, also eats terrestrial invertebrates.
Behavior: Male makes an aerial singing display. Pecks at surface for prey or probes for buried prey. Swallows small mollusks whole. Despite their gregariousness during the winter, pairs maintain breeding territories and generally nest about 1 km (0.7 mi) apart from each other.
Conservation: Red Knot is a global species. The IUCN Red List lists Red Knot as a Near Threatened species. The occurrence of large concentrations of Knots at traditional staging areas during migration makes them vulnerable to pollution and loss of key resources. At its peak, the Red Knot population in Hebei’s Luannan Wetland was 60,000. However, in recent years due to the reclamation of surrounding areas and other factors, by 2015 the number had dropped to just over 20,000.
There are three subspecies in North America, and they all appear to be in decline. The populations wintering in South America dropped over 50% from the mid-1980s to 2003, and are listed as a federally threatened species in the United States. A 2012 study estimated the total number of all three North American subspecies at about 139,000 breeding birds. The North American Red Knot is on the “2014 State of the Birds Watch List”, which lists bird species that are at risk of becoming threatened or endangered without conservation action. This is in line with the situation in China, which means that the birds will become threatened or endangered if protection measures are not taken.