Wood thrush is a scarce delight

The first wood thrush that I’ve heard in quite a while in my wooded backyard in Decatur recently serenaded us with his rich, beautiful song on a sunny morning. It was a welcomed presence, because the wood thrush is one of Georgia’s native species in serious trouble.

The wood thrush has become a symbol of declining neotropical migrant birds, according to the Cornell Lab of Ornithology in New York, which says the bird’s population has decreased significantly since the late 1970s. Annual breeding bird surveys show that wood thrush numbers are decreasing by an average of 1.7 percent annually.

Acid rain, along with fragmentation of forests in North America (its summer nesting grounds) and in Latin America (its wintering area), are prime reasons for the wood thrush’s falling numbers.

Another major problem is “parasitism” by brown-headed cowbirds, which lay their eggs in other birds’ nests, often tricking the birds into raising cowbird babies. In some areas, wood thrushes may be raising more baby cowbirds than their own young.

Forest fragmentation refers to the carving up of large swaths of forests into smaller parcels separated by roads, farms, houses, shopping malls and other development. Chopping up a forest into smaller units creates more “forest edge,” a configuration that makes bird nests, eggs and young much more vulnerable to predators such as raccoons, squirrels, grackles, crows and cowbirds, which also favor forest edge habitat.

According to the Smithsonian’s Migratory Bird Center: “The candle is burning at both ends for the wood thrush, as it is for many birds that breed in temperate North America and winter in the tropics of Latin America.”

Some conservation groups warn that the wood thrush, a close cousin of the robin, is close to endangered status.

Spring in Georgia would be far less joyous without the male wood thrush’s resonant, flute-like trill, which goes something like “ee-o-lay” and is perhaps the most melodic of any North American bird.

“You would have to go to the tropics to find a sweeter singing bird than the wood thrush,” says Lisa Hurt of Atlanta Audubon.

Naturalist Henry David Thoreau found special solace in the wood thrush’s bell-like notes: “The thrush alone declares the immortal wealth and vigor that is in the forest.”

The wood thrush, which sports a cinnamon back and a white chest with brown spots, has the equivalent of two sets of “vocal cords,” the main reason for its extraordinary vocal versatility. Thus, it can sing two overlapping songs at once — or sing with two voices simultaneously.

In the sky: The moon will be last quarter on Monday — rising about midnight and setting around midday, says astronomer David Dundee with Tellus Northwest Georgia Science Museum. Mercury, Venus and Mars are low in the east just before sunrise. Venus rises about two hours before the sun and shines very brightly in the predawn sky. Venus and Mars will appear near the moon Friday morning. Jupiter rises out of the east before midnight and appears near the moon tonight. Saturn is high overhead at sunset and sets about midnight.