Thursday, July 7, 2011
(Transcript of today's For the Birds)
If I had to choose 10 favorite bird songs, the list would definitely include the Veery. This mellifluous song cascades through woodlands most reliably in the evening, right when many people are sitting on their porches to enjoy the performance. Veeries belong to the genus Catharus, which comes from the Latin word pure, in reference to the pure tones of these thrushes’ songs. Intriguingly, another North American bird whose name start with V, the Turkey Vulture, also shares the derivation of its scientific name, Cathartes, but for a wildly disparate reason. The Turkey Vulture genus name was given in reference to a cathartic, which purifies or purges the digestive tract. When a predator approaches a vulture who can’t escape, the vulture purges its stomach contents via projectile vomit. Vultures like their meals not just merely dead but really most sincerely dead, and what comes out their throats is much, much yuckier than what went in. Fortunately for those of us who enjoy Veeries, what comes out of their throats is pure and sweet. Veery songs sound similar to our ears, but Veeries can distinguish fine points in one another’s songs to recognize the sounds of their neighbors, which don’t seem to upset them. But they react aggressively when an unfamiliar Veery song is heard near their territory.
It’s rude to play recordings of their song to draw them close because they get so distressed. If a person must play a Veery recording for research or other purposes, it’s kindest to play the song very softly before stopping. In a 1956 study, researchers found the louder a taped song was played, the more a Veery tried to escape; the lower the volume, the more likely the bird was to assume an attack stance. Both the bird and his mate might assume he lost the encounter if he was retreating during the last, loud song played, but that he won the encounter if the sound grows softer and then disappears.
The Veery isn’t the only thrush in the upper Midwest—robins are the most abundant, but in our own north woods we also get Swainson’s and Hermit Thrushes, and even an occasional Wood Thrush. Of all these species, Veeries prefer the youngest, wettest woods—I expect to hear them wherever I see a dense stand of ferns. During migration through Central America, they are more drawn to mature second growth forest, and that’s also their preferences on their winter range in the cloud forests of southern Brazil. Every Veery who we’ve heard singing this year has already made at least one round trip journey a minimum of 5,000 miles each way. The oldest Veery on record was an adult female caught in New Jersey in July 1980, and recaught, alive and healthy, in July 1989, when it was a minimum of 10 years old and had migrated over its lifetime a minimum of 100,000 miles.
During the brief time that Veeries are with us, from early May through late August, they mostly remain hidden in the vegetation, unobtrusively raising their young on insects and fruits and trying to steer clear of snakes, chipmunks, red squirrels, and other predators of eggs and chicks. White-tailed Deer are known to eat the eggs and chicks of ground nesting birds, though I couldn’t find any data establishing that they are a significant problem for Veeries as predators. But deer also browse the understory plants that define Veery habitat. During their nocturnal migration flights, they’re frequent victims of collisions with lighted structures. And on their wintering grounds they are harmed by deforestation. It’s tough to be a Veery, and sure enough, their numbers throughout the continent have been declining steadily since the 1960s, especially in a large swath of land that includes Minnesota and Wisconsin. I don’t know what we need to do to protect these beautiful birds with their shy ways and sweet songs, but without them the north woods would be diminished indeed.
Laura Erickson at 9:11 AM