Red Knot (Calidris canutus rufa)

4th September North Monomoy Island Cape Cod – 7 Red Knot. We had come out by boat to this windswept deserted 8 mile long spit of sand southwest of Chatham with a group from Massachusetts Audubon. Waders and shorebirds as far as the eye could see, though nothing unusual. As we were leaving, someone spotted the Red Knots in the far distance and we shared the telescope to take a better look. It was only later that I came to realize the significance of that sighting as I learned more about this remarkable bird.
Later on and casually thumbing through a borrowed magazine, I happened upon a book review. The book was by Deborah Cramer and was entitled ‘The Narrow Edge: A Tiny Bird, an Ancient Crab & an Epic Journey’. Thanks to Kindle, I was reading it within 5 minutes! The book is an account of how the author accompanied these birds on their extraordinary journey along the length of two continents, from remote Tierra del Fuego where they overwinter, to the high Arctic where they breed, and back again. In the book the author mentions how on the birds’ return from the Arctic, they stop at one point on a ‘low lying Cape Cod beach whose nearby waters are increasingly visited by great white sharks’. It was only then that I realized that the birds we saw were staging on Monomoy on their way back from the Arctic to South America. Awesome!
The Red Knot, Calidris canutus rufa, is one of six subspecies of red knots worldwide. On migration rufa flies the greatest distance of them all, a near miraculous 19,000 mile journey from one end of the earth to the other and back. One Red Knot B95, named for his leg band number, has been nicknamed ‘Moonbird’, (see photo above) as researchers calculate this long-lived bird has flown enough miles to journey to the moon and at least halfway back. He was aged at least 20 years old at his last sighting in May 2014. The exact migration routes and wintering grounds of individual subspecies are still somewhat uncertain but it is thought that the wintering birds found on Florida beaches may be a different subspecies that breeds on Wrangel Island in Siberia and north-western Alaska. So it is interesting to note that on September 26th Kathryn Young sighted 15 unbanded Red Knots on Siesta Key along with a mixture of other peeps and wading birds.
Red Knots have many homes, each a critical way station, where they fuel up on small clams and mussels ready for the next stage of their journey. In spring they time their arrival in Delaware Bay to coincide with the spawning of Horseshoe Crab eggs, where they gorge themselves for the final stage of their journey. During these times they can double or even triple their weight. More recently the birds have become threatened as a result of commercial harvesting of Horseshoe Crabs for fertilizer, bait and medical applications.
On their wintering and migratory grounds red knots eat a variety of hard shelled prey such as bivalves, gastropods and small crabs that are ingested whole and crushed by a muscular stomach. While feeding in mudflats Red Knots are tactile feeders, probing for unseen prey in the mud with shallow probes, while pacing along the shore. They are able to detect mollusks buried under wet sand from changes in the pressure of water using sense organs in their bill.
In 2014 the Red Knot rufa was listed as a federally threatened species under the Unites States Endangered Species Act. The reasons given for the rufas listing were: habitat degradation, loss of key food supplies, and threats posed by climate change and sea level rise. This is the first bird to be so listed because global warming imperils its existence, it will not be the last.
Glynnis Thomas