Changing Spring Skies -Spring 2020
Arrivals and departures of our avian friends
by: Virginia Andrews
Spring, the ancient philosophers tell us, is neither one thing nor the other, but contains elements of both winter and summer. Nowhere is this more evident than in our island birdlife.
Birds that have been here all winter begin to get restless. Birds wintering in more tropical zones, with Nantucket their summer destination, head north. Year-round residents shift into breeding mode. They are all in a race to secure the best nesting territory, hoping to ensure survival for their offspring.
Actual departure dates are a bit unpredictable. Birds do not read bird books. They often confound both statistics and ornithologists’ expectations. For example, Snowy Owls usually leave by the beginning of April. But in one exceptional year one lingered at Great Point until July 12. This is what keeps us interested.
Sea ducks are among the earliest to leave. Harlequin Ducks, if they have found mates, usually depart for the far north in mid-March. Common Eiders also leave early. They deal with still un-melted terrain by plucking their own breast feathers to make their nests, sheltering eggs and young. Although a handful sometimes remains in our area, the vast numbers of them will be gone by the end of March. Long-tailed Ducks, unusual in that they molt in three stages and almost reverse plumage color, use both coastal and interior areas. Alcids such as Razorbills also take off at the end of March. As inland lakes thaw in the north, Common Loons leave the salt and head back to fresh water.
Other sea and pond ducks begin showing signs of migratory restlessness during April. There is a good deal of competition. Raucous calls, head-bobbing, racing, splashing, dunking and just generally showing off are behaviors which some birders tactfully refer to as just “getting feisty.” Some form flocks or join others before committing to the actual trip.
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