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Brunswick Wildlife: Cranking it up, birdsongs are back!

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By Staff Brunswick Beacon

Last week I noticed it. The first songbird to sing this spring in my neighborhood was the house finch. On the following Sunday morning, while birding in Southport, I noticed eastern bluebirds singing in several locations. In fact, numerous species were singing that warm morning.

Birds are heralding the approaching spring breeding season, well before the neotropical migrants have returned to join the chorus. The finch and bluebird are year-round residents that show no respect for those orioles, buntings, vireos, and warblers still basking in the warm sun of the Caribbean, Central America, and South America.

There is disagreement among ornithologists of an exact definition of birdsong. Birds have other vocalizations such as calls and chips. Generally, songs are considered to be longer, more melodious, and more complex.

Males sing, usually from high perches, to establish territory, hierarchy, and to attract females. Females, in turn, listen to assess potential mates. Scientists theorize the quality of a male’s song and the extent of its repertoire are good indicators of a male’s breeding fitness, health, and ability to hold high quality territory.

Short notes and chips may be characterized as mobbing, alarm and contact calls. The communication may be within a species or even across species; however, the message is understood. Alarm calls may be different for ground versus aerial predators and multiple species may be observed taking appropriate actions.

By now your bluebird box should be cleaned and ready. Bluebirds are with us year-round; however, they do a partial, regional migration. The ones you see today may head north and be replaced tomorrow by “your” returning bluebirds.

For their first brood of the season, bluebirds begin building nests in late February through March. The female builds the nest inside a natural cavity or nest box without the help of the male. While photographing this male supervising, I watched the female make several trips to the ground to gather dead grass.

The funny thing is the male often holds nest material at the entrance to the nest to attract the female, which is a nest demonstration display. He gets her attention, but somehow he gets out of the work. That doesn’t ring true, does it? In the male’s defense, he will contribute as much to feeding the young as the female.

The house finch, originally a western bird, has colonized other regions of the country, rapidly spreading west from a small colony of birds released on Long Island in 1940. Its original range was from Colorado, West Texas, and Mexico to the California coast and up to British Columbia.

This is a very abundant bird, easily seen in backyards due to its love affair with seed feeders. Its numbers, however, have been reduced over the last decade by finch eye disease, yet it remains common throughout its range.

Like bluebirds, house finches go through a regional migration during winter with some birds shifting southward based on food availability. Finches wintering with me may not be the ones that nest in my yard; however, I can count on seeing families of finches at my feeder by late spring as the young are taught to forage.

For me, the cacophony of winter blackbirds and grackles will yield to a symphony of birdsong. The seasonal beginnings will lead to a crescendo—the phenomenon known as the “dawn chorus.”

The dawn chorus, most notable in spring, is a powerful songfest. It features the largest number of singing birds; they sing more frequently and energetically and with more variety than later in the day. Males begin an hour or two before sunrise. Each species joins the chorus at slightly different times and levels of light, in a fairly regular sequence from day to day.

Some birds have a dawn song that is different from their normal daylight song. They slow down from their frenetic dawn song. Some use different patterns of combining their song types at dawn, using more frequent changes in type than they will use later, or they may not switch types later in the day as they do at dawn.

Males may also belt out their high-energy song from different locations at dawn than the remainder of the day. For example, a chipping sparrow’s dawn position is generally on the ground while it perches on high during the day.

Reasons behind the dawn chorus phenomenon are not well understood. There are probably multiple objectives that may differ among species. Researchers have proposed possible explanations including: dawn is the best time to attract a mate, the calm conditions at dawn allow sound to carry a maximum distance, it is too dark to forage so why not belt out a tune, and finally for territory defense and a daily reconfirmation of its established social position. Some researchers believe the chorus wanes when there is enough light for birds to fly off to forage.

We celebrate the phenomenon as International Dawn Chorus Day that will be on Sunday, May 4. More information on this celebration may be found at its Web site: http://www.idcd.info/

While writing an article, I generally use Google for appropriate subjects for background reading and fact-checking. A Web site that offers links to other sites with bird sing samples may be found at: http://www.math.sunysb.edu/