Dead eiders like clockwork

Great Island on Cape Cod in Massachusetts: site of the eider die-off (photo: D. Jordan)

Right on schedule, eiders have begun turning up dead on Cape Cod once again. The last reported die-off occurred at exactly this time last year,and the profile of birds involved is similar once again: mainly males with occasional adult females. While determining the cause of these die-offs has been a long, often arduous process, this year we are better positioned than ever to make progress. The reasons for our optimism are mainly personnel based: we have a new “eider intern” on the ground on the Cape. Ashley Gorr will be surveying the Great Island area, which is generally the epicenter of these events, and she will be collecting wings from some of the birds for examination by experts. Getting an accurate age on male eiders is notoriously difficult, but details of wing plumage can assist in the process. Ashley will also collect data on live birds present in the area so that we will have a sense of what proportion of the local eider population is apparently involved in the die-off.

In addition to Ashley, we have a new SEANET volunteer, Dick Jordan, who has taken on Great Island’s western shore as his SEANET route. This is something we have longed for for many years, so we offer our profuse thanks to Dick. On his beach walk on October 13 (an epic seven hour tour!) Dick recorded 18 dead or dying eider, a Herring Gull, and a Ring-billed Gull. This introduction to SEANET surveys was quite a grueling one, and we hope that Dick will enjoy more leisurely walks once the die-off abates. He even made a valiant attempt to transport a sick female eider to a wildlife rehabilitation center, hiking an hour out to his car with the bird. Unfortunately, she died upon reaching the parking lot. A second bird Dick tried to transport died en route to the rehab center. Birds involved in these events have notoriously low survival rates; in fact, SEANET does not know of a single survivor over the many years these die-offs have been occurring.

A profoundly weak female eider. She died hours later. (photo: D. Jordan)

Working off of a tip provided by Dick, Randy Mickley of the USDA headed out to Great Island on ATV to collect numerous sick eiders. He captured 13 seriously ill birds which were then humanely euthanized and will be examined by veterinary pathologists at two institutions in an attempt to get closer to a definitive answer on these events. Special thanks also goes to Chris Dwyer of the US Fish and Wildlife Service who has been exceedingly supportive of this investigation all along and has provided coordination and assistance at every turn. Finally, thank you to Bob Cook of the National Park Service, who granted Randy ATV access to the site so he could collect the birds just as night was falling. It all converged to create a very dramatic picture of collaborative science in action.

We will keep you posted on the results of the autopsies of the 13 birds, and thank you to all parties involved here–your cooperative spirit is affording us our best chance yet of building on previous years’ work and getting to the bottom of this!