Canada and Snow Geese migrating north above Vernon Dam

The rains of March 13-15 coincided with an important date in my calendar.  Mid to late March is prime time for goose and duck migration in New Hampshire.  It is impossible to predict the exact timing from year to year due to a number of variables, but the general migration window is set.  It has evolved over generations to ensure that the birds arrive on their breeding grounds early enough to secure a good mate and raise a brood but late enough to avoid the really nasty weather.  Birds cannot risk arriving on the breeding grounds too early and being stranded “behind enemy lines” if the weather closes in behind them.

Within that window, weather conditions affect their day-to-day decisions to move further north.  Locally, the date of ice-out on the Connecticut River is an important determinant of the degree to which waterfowl will linger in the area.  If the “weather front”, the latitudinal gradient north of which rivers and fields are still frozen, has not advanced to far north of the NH/Mass state line by mid March, then a good waterfowl year is promised.

This year Punxutawney Phil cast no shadow and spring came early to the Connecticut River Valley.  The ice disappeared from the river above Vernon Dam by early March and the fields were largely free of snow.  I visited the roost on March 16^th and counted barely 200 birds between Vernon Dam and Hinsdale boat launch opposite the large cattail marsh.  The river and fields were clean of ice and snow all the way north through Charlestown.

In 2007 the ice remained on the river until at least March 31.  I have count data from the evening of March 28^th of that year when more than 5,000 birds crowded the ice and pools above the dam, including snow geese, 4000 Canada geese, a barnacle goose, 68 wood ducks, gadwall, wigeon, black duck, mallard, 44 pintail, 226 teal, ring-necked duck, hooded and common mergansers, and goldeneye.

This year the birds perceived the good conditions on the ground as a call to continue north.  I know this because I was at Vernon Dam most evenings scanning for birds.  It was tremendously exciting to see them pass overhead, even if few stopped.  I could tell the short haul from the long haul geese easily as the short-haul variety passed relatively low overhead on a downward glide.  They would roost in a cornfield not far upriver.  The long haul variety flew north at great height, almost beyond the limit of binocular vision.  They flew on a similar track to the trans-Atlantic aircraft whose route to Europe takes them over Greenland, the destination for many of these birds.

Next week I will venture along the Connecticut River north of Hanover to see if the birds have thrown caution to the wind and quit the state for Canada, a risky strategy in mid March.  Join New Hampshire Audubon’s Monadnock Chapter on March 28^th for a trip along the river in search of waterfowl.  Meet at the Charlestown Library at 8am for carpool.