After days of high winds and rough water, the forecast on October 6 was finally for calm weather, but with 100% chance of clouds. Clouds of shorebirds, that is. You see, I was helping with the US Fish and Wildlife Service Red Knot trapping project that day at South Beach in Chatham, home to the biggest shorebird roosts in the state.
Throughout the day there were indeed clouds of shorebirds – huge flocks of Black-bellied Plovers, Dunlin, Sanderlings, Red Knots and a few other shorebird species that come to South Beach to roost on the high tide.
While these massive flocks created an awesome avian aesthetic, it was the Red Knots we were after. Red Knots nest in the high Arctic, and a good chunk of the population winters in southern South America and then each spring passes through Delaware Bay, where they gorge on horseshoe crab eggs. Both migration and breeding are energetically expensive, so they really need to pack on the pounds. Given these life history strategies, knots are vulnerable to climate change, which is disproportionately affecting the high Arctic, as well as over harvest of horseshoe crabs on those spring stopover beaches in Delaware and Maryland. These factors seem to be fueling alarming population declines in long-distance migrating knots, which is why they were listed as Threatened under the US Endangered Species Act three years ago.
The goal of this research is to track the migration of juvenile Red Knots to discover key staging and wintering areas and to protect those habitats. Tiny data loggers are fitted to their legs to record the location of the birds throughout the year. Kate Iaquinto and Stephanie Koch of Monomoy and Wildlife Biologist Larry Niles of New Jersey head up the project, which is in its 8th year. Larry has trapped and banded Red Knots from Cape Cod to Brazil, but does most of his work in Delaware Bay, where most of the longest distance migrant knots come each spring to gorge on horseshoe crab eggs.
The methods create a logistical nightmare on these remote Chatham beaches surrounded by shifty channels. Getting all of the necessary gear and personnel on and off the beach during the narrow navigational windows around high tide is no mean feat. The huge nets used to capture the birds are attached to hefty iron projectiles fired from cannons. While the gear is buried and well camouflaged, if the birds don’t want to come near them, there is little you can do. And this year, the knots were not cooperative.
This was very much a down year for Red Knots on Cape Cod. Tiny juvenile blue mussels, their favorite food, were scarce in Pleasant Bay this summer. Whereas I would normally see 300-600 Red Knots feeding on mussels at Mass Audubon’s Tern Island in Chatham, there were almost none this year. Numbers at the usual high tide roosts in Chatham including South Beach, North Beach Island, and a few different parts of Monomoy, were down as well. Numbers at key staging areas north of us, like James Bay in Canada, were also down by at least 50%. The low numbers may be linked to colder than normal weather and water temperatures in Delaware Bay this spring, which limited horseshoe crab spawning, and hence the availability of their tasty, fatty eggs. Not able to gain enough weight, knots could have had trouble reaching the high Arctic nesting grounds and breeding successfully.
Thanks to the lower numbers of knots, and the stormy weather that limited our field days, this was not a successful year for the Red Knot project – no birds were trapped. Like the Red Sox, we are left to assess what went wrong and think about next season. After another playoff collapse the Red Sox clearly need clutch hitting and better leadership in the clubhouse. The shorebird team just needs some better weather and more cooperative Red Knots. Frankly, when it comes to the possibility of going all the way next year, my money is on the Red Knot team.