Birds : The season progresses
The temperature is still cold. It is undeniably still winter, but spring is in the air. The calendar we use delineates the start and finish of the seasons at a certain time on a specific day. In the natural world timelines are not nearly so clearly defined.
On the evening of February 15, American woodcocks were engaging on their unique flight displays just at dusk in several overgrown fields. Shortly before writing this a song sparrow, two northern cardinals, a white-breasted nuthatch, two Carolina wrens, and both downy and red-bellied woodpeckers were singing persistently. It is 7:15 am, the temperature is 25 degrees with a light north wind, and the sun is shining. It sounds like it is late April, not mid-February outside.
Photo by E. Vernon Laux
The photoperiod - the amount of daylight - is rapidly increasing. Birds' endocrine systems respond to this and begin to produce hormones to prepare for the quickly approaching breeding season. So while we keep the wood stoves stoked, the furnaces turned on, and huddle to stay warm, resident birds are already proclaiming their stakes to nesting territories.
The first land bird to return north in spring is invariably the red-winged blackbird. They were singing in many wetland areas on mornings this past weekend. These hardy and extremely successful and adaptable birds nest in virtually every swamp, grassland, and mixed successional habitat in the northern United States and southern Canada. Generally, migrants of this species return to the Vineyard on or around the 20th of February. In the last week, the birds showed up even earlier than in past years, again. They are early once again and the National Audubon Society has just released a study showing that some 80 percent of land birds are gradually shifting their respective winter ranges northward. Many are calling this convincing evidence of global warming.
Generally, a small number of individuals of this species spend the winter on the Vineyard. This year was no exception as at least three flocks of approximately 30 to 40 birds over-wintered. But the appearance of birds at far-flung locations where they have not been all winter is clear evidence of newly arrived birds from farther south. Presumably most of these early arriving birds are here, staging for the next leg of their journey, preparing to head for breeding areas well north of Martha's Vineyard.
Also arriving is another hardy blackbird - the common grackle. These large, iridescent, long-tailed birds seem to be returning north earlier every year. Red-winged blackbirds used to show up a couple of weeks before grackles, but for the past five years the arrival dates back on the Vineyard for the two species have almost coincided. A small number of this species also spent the winter, but again several flocks have been seen and birds showing up at locations where they were not seen all winter indicate that these are migrants.
With the moderating temperatures after the extreme cold of January, more and more surface water is returning to a liquid state. Waterfowl are quick to exploit these areas. The Head of the Lagoon, also known as the Oak Bluffs pumping station, has been a fantastic spot to see concentrations of various ducks at close range. American wigeon, gadwall, ring-necked ducks, greater scaup, hooded mergansers, common goldeneye, bufflehead, and canvasback have all been frequenting this location in the past week.
Male American goldfinches are visibly changing from their dull olive winter garb to the much brighter yellow that they sport during the breeding season. Many people call these small colorful birds wild canaries. Their spectacular coloring brings to mind birds associated with a more tropical setting. Feeder watchers all over Martha's Vineyard have noted this change in these common and frequent visitors.
Sea ducks are getting restless and can be seen displaying and courting. With the days growing longer these very tough birds have thoughts of heading north to breeding areas devoid of trees. Imagine thinking of the winter waters surrounding the Vineyard as a winter paradise. That is what it is for these birds of the far north. The waterproofing and insulating property of their feathers boggles the mind.
It is interesting to note that males court the females attempting to win her favor with stunning plumage and good display moves. As they get closer to breeding grounds it is the male who follows the female to an area of her choosing for nesting. Usually, females return to the same area where they were hatched.
The food resources available in nearshore waters in the form of blue mussels and crabs must be enormous. The food required by the millions of sea ducks that spend the winter in Nantucket Sound, Vineyard Sound and adjacent waters on the south side of both the Vineyard and Nantucket is staggering to ponder. Currently, these waters remain clean and productive, relatively free of pollution.
Long Island Sound on the other hand is basically devoid of wintering sea ducks. Should increased industrial development occur in this region - for example the proposed 24-square-mile wind industrial park proposed for a large area of Nantucket Sound - things would change for this most important wintering area. It is hard to imagine habitat would be improved for birds.
There is a sense of anticipation in the natural world now, as the end of winter seems certain, just not quite at hand. Birds that are present are newly energized and exhibiting new behaviors. However, food, never abundant in winter, is scarcer still at this season. All birds, ranging from fish-loving loons to mussel-eating eiders, meat-eating red-tailed hawks to seed-eating song sparrows, are hungry. If you have been feeding birds all winter, don't stop now. This is the most critical time as any fat reserves birds had have been depleted.
Spring is in the air in the form of bird song but winter still clings to the thermometer. Until next time - keep your eyes to the sky.