On Tuesday September 17, 2013 at 6:30pm, the Orleans Conservation Trust (OCT) hosted the first of three presentations associated with our Third Tuesday Fall Lecture Series at the Orleans Yacht Club. Brian Harrington, Ermitus Biologist retired from the Manomet Center for Conservation Sciences, delighted over 40 interested Cape Cod residents with his lecture entitled “The Red Knot, From Patagonia to Cape Cod.”
During Harrington’s tenure at the Manomet Center for Conservation Sciences, which stretches back to 1971, he focused on shorebirds, in particular the long-distance migration strategies typical of these birds. His research has followed the birds, from northern North to southern South America with a particular focus on Red Knots.
During the lecture Harrington explained that the Red Knot is a shorebird, meaning they are not ducks, gulls, or herons, but in fact a smaller bird species more closesly related to the sandpipers that feeds along shoreline mudflats. After years of studying these birds, scientists are only recently beginning to understand how amazing the Knots’ migrations are. The Knot routinely travels between their summer nesting grounds in the high Artic down to their winter quarters near the southern tip of South America. During that migration the birds often fly over the open ocean, at elevations as high as 20 thousand feet, making just a few stops along the way. One tracked bird flew 4,800 miles over 6 days without stopping! One Knot that has been documented to be more than 15 years old has been nicknamed the “Moon Knot” because it has flown an equivelent distance to the moon and back.
Much of this information has only recently been gathered thanks to numerous volunteers, scientists and government agencies in North and South America working together to catch the birds and band them with region-specific tags. These bands are considered harmless and allow researchers to study the Red Knot poulation size and change, migration and stopver locations, and survivorship and mortality rates. All of this information is vital for conservation planning. Scientists have even been able to install miniature tracking devices on a few birds that contains a clock, a microprocessor, and a battery. This ‘geolocator’ records geographic location every 10 minutes. Once the bird is captured again all the recorded information is retrieved for further evaluation.
Harrington explained that there is a historical pattern of Red Knots using two principal regions of the MA coast during southern migration (at Billingsgate Island in Wellfleet and in Duxbury), and that the overall numbers of those particular Knots has been declining since the 1970’s. However, the population of Knots that use Cape Cod as a stopover has not changed. Knots visiting Massachusetts today (focused on the mussel flats at Little Sipson’s Island or off Monomoy in Chatham) are from 2 different wintering areas; South America (Patagonia) and the northern wintering area within the Caribbean and Venezuela. The decreased numbers of Knots from the Patagonian group seem to account for the overall decline of Knots in Massachusetts. The relatively stable numbers on Cape Cod probably are due to increasing numbers from the northern wintering group offsetting decreasing numbers from the Patagonian-wintering group.
At a local level, Harrington went on to discuss the recent shift of the Knots from the southern region of Pleasant Bay to the northern region, in and around Little Sipson’s Island, which OCT purchased in the early 1990’s to be preserved forever. In the 1990’s, Pleasant Bay split into a north bay and a south bay when the outer beach re-connected to the Chatham mainland. When this split took place the cold, nutrient-rich Atlantic water no longer reached the South Bay. This quickly changed the invertebrate animal community, including the number of clams and crustaceans available as a food source. Today, ironically, few clammers and few Knots work and feed in the South Bay flats where just 5 years ago both the clammers and Knots were active.
Worldwide the Knot populations have been dropping faster than any other bird species. Blame for the decline of Knots has been placed on loss of key food sources, one of those being the BB-sized eggs of horseshoe crabs, especially in Delaware Bay, one of the major stopover areas for the birds while migrating northwards. The Knots arrive to refuel on the small eggs, but because of over-harvesting of crabs there is a shortage of the eggs, preventing the Knots from getting enough fat. Not having enough fat leads to them running out of fuel during their next migration link before reaching their Arctic breeding grounds, leading many to die off. Like many other situations, the birds are competing with our own needs. Harrington noted that while it has taken a long time, a balance is being formed between the needs of the migratory shorebirds and local harvesting of horseshoe crabs for our own purposes.
For more information, see Harrington’s text on “The Flight of the Red Knot”. He also suggested an interesting video on shorebird migrations called “Epic Journeys” by Migration Productions that showcases the annual migration of Red Knots, Piping Plovers and Semipalmated Sandpipers.
The entire event was a successful start to the OCT’s Fall 2013 Tuesday Lecture Series, which will continue on the third Tuesday of each month at the Orleans Yacht Club until the end of November. Join us on October 15, 2013 at 6:30pm for the next lecture entitled, “Orleans: A Small Cape Cod Town with an Extraordinary History” given by Bill Quinn, local author and historian.