Large Flocks of Waterfowl Feeding Furiously in East Harbor Lagoon this Winter

Date: January 10, 2007
Contact: John Portnoy, Park Ecologist, [phone] x107
Contact: Robert Cook, Biologist, [phone] x106

Massachusetts Coastal Zone Management and Cape Cod National Seashore staff report flocks of hundreds of sea and bay ducks, of at least 13 species, on East Harbor lagoon this winter. Small numbers of some waterfowl, like black ducks, buffleheads and red-breasted mergansers, have wintered on this back-barrier embayment for many years, but the recent increase in species diversity and flock size, a likely consequence of recent tidal restoration, is a new and exciting development. For example, the recent Stellwagen Christmas Bird Count includes East Harbor in the count area; birders tallied 70 Black Ducks, 6 Mallards, 9 Redhead Ducks, 125 Greater Scaup, 4 Lesser Scaup, 150 White-winged Scoter, 6 Surf Scoters, 20 Common Goldeneyes, 100 Buffleheads, 75 Common Mergansers, 20 Red-Breasted Mergansers, 7 Hooded Mergansers, and 45 Ruddy Ducks “feeding furiously” in the lagoon. Several of these species have never before been recorded on East Harbor, especially the sea ducks like scoters, and never in such abundance.

Significantly, many of these birds dive to the bottom to feed on small shellfish and other bottom-dwelling (benthic) animals. Their active feeding on the lagoon this winter indicates that the diverse benthic community that reestablished over the past four years of tidal restoration continues to thrive despite an algae bloom, apparent oxygen depletion, and soft-shell clam die-off last summer.

Winter use of the lagoon by large rafts of diving ducks marks another step in the recovery of this original 700-plus-acre embayment and salt-marsh system, which until 1868 connected to Cape Cod Bay via a 1000-foot wide inlet. Partial tidal restoration undertaken by the Town of Truro and the Seashore beginning in 2002 has resulted in a rapid increase in salinity and the return of marine plant and animal communities missing from East Harbor since the system was diked off from Cape Cod Bay. Since 2002, regular monitoring has documented the reestablishment of submerged aquatic vegetation (mostly widgeon grass, an important habitat for fish and crustaceans, and an important winter food for highly prized black ducks), finfish, shellfish, crustaceans and marine worms.

Now that the sea ducks have, after perhaps a 140-year hiatus, “rediscovered” East Harbor, they should become a regular winter feature. Superintendent Price notes, “Again it is the marine animals that are reminding us that so-called ‘Pilgrim Lake’ is more accurately a coastal lagoon, with the potential to recover many of its native functions that we now readily appreciate and highly value.”

For general information on the East Harbor Restoration Project, contact Ecologist John Portnoy (508-487-3262 ext. 107). For questions specifically on the waterfowl, contact Wildlife Biologist Bob Cook (508-487-3262 ext. 106).