Birds and Ice Cover Estuaries for Lloyd Center’s December 2018 Waterfowl Survey by Jamie Bogart, Lloyd Center Research Associate
For last season’s December waterfowl survey, Lloyd Center researchers expected that high tides forecasted during a “Supermoon” would cause a low count. To their surprise, survey conditions were perfect and the highest December numbers in a decade resulted for that 2017 survey.
In this year’s first count, for the thirty-second annual Lloyd Center for the Environment's Winter Waterfowl Survey held on Sunday, December 9, a more common event influenced the outcome. For the first time since 2003, a weather postponement occurred due to rain which pushed the count back a week. This in turn allowed other aspects of weather to take hold. Instead of a survey on ice-free systems, extremely cold temperatures hit, creating the most ice since 2007.
This survey, in terms of timing, ice coverage, and waterfowl numbers, most closely resembled the last postponement year of 2003. As far as ice, this survey observed the most since the January / February survey in 2015, which depicts the overall mild trend when even the mid-winter counts have featured lower than normal ice coverage. This survey also supports the assertion that increased ice coverage for the December count will often correspond with more waterfowl along the coast because saline systems with even minimal ice means inland systems are frozen solid.
This year’s 8,494 total birds counted is a huge increase by 2,589 birds over last year’s number. Of this increase, 88% or 2,276 are Canada Geese, the highest number of geese observed during the December 2003 count. The other huge increase occurred for Mallards, from 378 last year to 1,582 birds this year, the most Mallards ever counted! The other familiar species acclimated to people, Mute Swan, showed almost no change, increasing from 384 last year to 387. For American Black Ducks, the most abundant duck species not acclimated to developed areas but for which a robust migrant population exists, an increase by a few hundred birds to 1,386 made for the highest Black Duck total since December 2013.
Nonquit Pond, a large pond that also had relatively low ice coverage, had by far the highest counts for both Canada Geese (749) and Mallard (913) and is the primary site resulting in this year’s high count. Canada Geese numbers were also high in the Westport River, Cockeast Pond, and Round Pond, and Mallards in the Slocum River, Briggs Marsh and Nannaquaket Pond. We can be sure this includes some birds resting on ice or salt marsh. Black Duck counts were highest on the Westport River, Allens Pond, Salters Pond, and Little River. American Wigeon was one dabbler showing considerable decline.
As expected with ice coverage present, the most common divers including Bufflehead, Red-breasted Merganser, and scaup species all declined. However, Hooded Merganser, a diver which has responded to nest boxes and is adept at finding space in small shallow secluded embayment’s and is often seen foraging near ice, increased. The jackpot for “Hoodies” was Quicksand Pond which had ice coverage of 95%, and is where the largest flock of scaup was also counted. So, although divers generally decline with increased ice coverage, including species that may retreat out to the open bay, pockets of optimal open water habitat still exist and may attract sizeable concentrations of birds.
Tune in next year to see how weather patterns dictate the outcome of the midwinter count, including abundance of species and overall diversity.