Birds and other wild creatures “know” about the upcoming winter and other things from inherited genetic information; if it is not their first year of life, they have the benefit of experience as well.
The autumnal equinox heralding the triumph of darkness over light in a 24-hour period at this latitude has just occurred. We know this because we can read the calendar, have experienced this before, and even notice the decreasing amount of daylight and changing angle of the sun. Birds and other wild creatures “know” about the upcoming winter and other things from inherited genetic information. If it is not their first year of life, they have the benefit of experience as well.
What birds “know” or, in some other way, “feel” is that the length of day is rapidly decreasing, insect food is getting scarce, cold weather is coming, and, if they are a migratory species, there is no time like the present to head south. So the annual phenomenon that is bird migration is at its peak on the Cape and Islands from now until mid-October. This is the time to see not only lots of birds but the greatest variety of species as well.
The first brown booby that managed to be seen by a lot of birders in Massachusetts, if it is the same bird, continues to thrill birders visiting the Cape. A birder on MacMillan Wharf saw an immature brown booby last weekend sitting on the Provincetown breakwater. A northern wheatear, a small bird that winters in southern Africa, was discovered on Nantucket on Sept. 19, but sadly, was a one-day wonder. These colorful, distinctively patterned birds are always a birding highlight anywhere in North America.
Lesser rarities were also reported this week: blue grosbeak, clay-colored sparrows, olive-sided flycatcher, yellow-breasted chat and numerous warbler species, including a yellow-throated warbler in Aquinnah on the Vineyard. Jaegers, falconlike seabirds, have been widespread off Province-town and Chatham, and lesser black-backed gulls are seemingly everywhere.
Local and visiting birders know that this is the absolute best time of year, hence anyone who can be out looking for birds generally is. The day after a clear night with a light or moderate northwest wind at this time of year is certain to attract whoever can be there, to try their birding luck at their favorite spots.
Many people know that most land birds migrate at night. On favorable nights, the sky is full of tiny travelers engaged in flight for their own individual survival, as well as that of their species. Warblers, vireos, flycatchers, orioles, sparrows, and other species could all be flying on the same night, not as a flock but as a loose conglomeration of flying birds, all heading, ultimately, in a southerly direction.
A couple of such nights occurred this past week. Standing outside in the early evening, admiring the stars and the Milky Way, away from extraneous noise and light, an observer could be nothing less than thrilled at the chips, notes and flight calls descending from the starlit sky.
The most abundant fall-migrant wood warbler is the blackpoll warbler. This wood warbler, weighing in at less than half an ounce, nests across the belt of spruce and tamarack trees, the boreal forest, from Alaska to Newfoundland across the top of North America. In the fall migration, virtually all individuals of this species head to the northeastern seaboard, even birds that nest more than 3,000 miles away in northern Alaska. Once arriving on the coast, the birds eat voraciously, gaining body fat that they are then able to utilize like gasoline in a combustion engine when they engage in spectacular nonstop flights from places such as the Cape and Islands to the Caribbean and beyond to South America. They are the champion long-distance migrants among the wood warblers.
Our region is fortunate to be geographically situated to receive impressive concentrations of birds that fly to the coast on northwest winds. They then literally “funnel” west at various western-facing hot spots. On mornings when there are large movements of birds at western funnel points, the sky can be dizzying with flocks of birds at various altitudes. Birds that have flown all night and have slightly overshot the coast want to return west and then south, staying along the coast of the mainland.
When they reach the end of the peninsula or an island, they look out and see nothing but water and then the mainland in the distance. To anthropomorphize, this has got to be scary for a little land bird, as there is no place to land, feed, drink or avoid fast-flying falcons in daylight over open water. Faced with this dilemma, the birds climb higher and higher into the air, gaining altitude, often climbing up out of sight of binoculars before heading toward the mainland in a combination gliding/diving/flapping flight. Often, there are birds at various altitudes: new arrivals lower, older arrivals already having attained more altitude.
Raptors and waterfowl are increasing dramatically now as well. A day afield at this season allows an excellent chance to find all three regularly occurring species of falcon, namely peregrine, merlin and American kestrel, as well as lots of accipiters. All ducks, especially the teeming numbers of sea ducks that overwinter in Cape and Islands waters, are starting to trickle in, and loons, grebes and other seabirds are on the move as well.
The birding is fantastic in late September and early October on the Cape and Islands.
Until next week – keep your eyes to the sky!
E. Vernon Laux's birding column appears every Saturday in the Cape Cod Times. Laux is the resident naturalist for the Linda Loring Nature Foundation on Nantucket. You can also hear him on “The Point” with Mindy Todd at 9:30 a.m. the first Monday of the month on the Cape's NPR station, WCAI, 90.1. He can be reached at firstname.lastname@example.org.