Birdwatching: When it comes to singing, this species is a real jukebox

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Bird songs have declined considerably in recent weeks. While doing fieldwork for the Atlas of the Breeding Birds of Maine, I was struck by how few veeries, yellow warblers, thicket birds, black-throated warblers, and white-throated sparrows that i heard on several sites in central Maine. The males of these species filled the air with their songs in June.

Of course, silence makes sense. Most of these birds fled young. The male no longer needs to sing to attract a mate or to warn other males to stay out of his territory.

However, there is one bird that sings vigorously until August: the red-eyed vireo. This species breeds widely in the eastern two-thirds of the United States and Canada. They are treetop birds, found in forests as well as in suburban parks and yards.

The red-eyed vireo is one of the most abundant songbirds in North America. Shutterstock

During the breeding season, males defend a territory of about an acre. A forest can therefore be home to many red-eyed vireos during the nesting season. Their modest size and wide continental distribution make the red-eyed vireo one of the most abundant songbirds in North America. One source estimates their population at around 130 million birds, making them the 12th most common bird in North America.

As canopy birds, red-eyed vireos are not easily seen without some effort. However, it’s a cinch to find one with your ears in during the Maine summer. The red-eyed vireo gives a singing vocalization consisting of one to five notes or syllables mixed together. Most songs consist of two- or three-note syllables. The male pauses briefly between songs.

Here is a mnemonic device to represent a sequence of red-eyed vireo chants: “here I am” – “here” – “in the tree” – “how are you”. Point your browser to the AllAboutBirds website to find records of red-eyed vireos.

Males are tireless singers. An equally persistent researcher counted all the songs given by one man in a day. For 14 hours, this vireo sang over 20,000 songs!

Although distinctive, the vocals of a red-eyed vireo are rather dull and monotonous. However, close examination reveals many interesting models.

Don Borror, an ornithologist at Ohio State University, published an article on the songs of red-eyed vireos in 1981. Although sometimes difficult to hear by ear, the songs of red-eyed vireos are quite varied. These differences are easily seen in sound spectrograms on a computer.

Borror analyzed 12,500 songs from 46 birds from nine different states. He found that song repertoires ranged from 12 to 117 songs, with an average of 40 songs per man.

A male almost never sings the same song twice in a row. Like a jukebox, some songs are played frequently and others are only used infrequently.

A 2020 article by Nicholas Acheson of McGill University significantly expands our knowledge of the vocalizations of red-eyed vireos. Although Borror analyzed 12,500 songs, Acheson’s work indicates that Borror’s sample size was too small. Most of Borror’s recordings were made in one day.

Acheson recorded the chants of 46 vireos over several days and at different times of the day. He found that song repertoires ranged from 17 to 341 distinct song types. The average repertoire size for individuals with over 1,000 songs recorded was 154. Astonishing diversity! Acheson’s results suggest that Borror and other red-eyed vireo researchers underestimated the size of the repertoire by two or three times.

Additionally, Acheson found that birds sang different subsets of their repertoire at different times of the day.

Acheson analyzed over 65,000 songs in his study, a Herculean effort.

Much remains to be learned about the songs of the red-eyed vireos. What influences variation in repertoire size in men? Do females use the size of the male repertoire to choose a mate? What do men communicate by singing different subsets of their repertoire at different times of the day?

Herb Wilson has taught ornithology and other biology courses at Colby College. It welcomes comments and questions from readers on [email protected]


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