Tuesday, February 10, 2009

Gallant in Gray: Townsend's Solitaire

Townsend's Solitaire photograph by Jerry Oldenettel

Stoically perched atop the tallest snag near the top of the canyon, he surveyed the valley below. Camouflaged by dusky gray plumage, he was nearly indistinguishable from the lighter gray skeleton that had once been a one-seed juniper. From this lofty vantage point, rivals could be as easily detected as winged predators that might threaten his very existence. Outwardly calm to the casual observer, he issued a single note call, “Tew,” sometimes repeated in a series, announcing his territory and warning others to stay away.

Although it was winter, he jealously guarded his turf and its bounteous crop of juniper berries. In fact, his very life depended on the berries so ferociously guarded, for they made up about 95% of his winter diet. It would take between 42,000 and 84,000 juniper berries, depending on berry size, to survive the winter season. He had won the right to this particular berry patch in the fall with up to six fights per hour with others of his kind who would usurp the territory. Now, with winter territories firmly established, he could relax his guard, albeit slightly.

Both sexes of Townsend’s Solitaires establish individual territories around patches of junipers in the autumn, and fiercely defend them until late winter. Territories range from very small, containing as few as two junipers, to quite large, up to 12 acres, containing several hundred junipers. Almost all territories hold more berries than necessary to sustain their owner throughout the long winter. Boundaries are sharply defined, and protected even from members of the opposite sex. Individuals are strongly site faithful to their winter territories, returning to defend the same set of trees each year.

By March, as daylight hours increase, this slender gray thrush experiences the hormonal surges that drive males and females to pair up and establish nesting territories. Like other thrushes, the male sings a complex, hauntingly beautiful song during a display flight, similar in some ways to other members of this family, which includes American Robin, Hermit Thrush, and Mountain and Western Bluebirds. After attracting a female to the territory, he cements that season’s relationship by either regurgitating food to the female, or offering berries. During the spring and summer, spiders and insects, particularly moths and butterflies make up a large portion of their diet.

However, domestic bliss may not reign supreme in solitaire land, as both males and females have been known to indulge in extra pair copulations. By mating with more than one individual, each clutch has a higher degree of genetic variability, essentially a safety net to produce the most fit offspring. Females also have been documented laying eggs in the nests of other solitaires, thus increasing their chances of producing successful offspring with little extra energy demands.

Like other members of thrush family, immature solitaires are heavily spotted. Each feather is edged in black giving the young bird the appearance of a heavily ornamented scallop design on its body. The first time that I saw a juvenile solitaire, many years ago in Bandelier National Monument, I was at a complete loss as to how to identify it. On closer inspection though, the bold white eye ring that both youngsters and adults show, helped me to figure out the identity of the bird.

Because of its specialized winter diet, Townsend’s Solitaire is heavily dependent on juniper woodlands, a particularly under-appreciated habitat type. Throughout the West, many grassland restoration projects focus on large-scale removal of juniper in an attempt to create more forage for cattle and other browsing animals. Loss of mature trees and their berry crops affect not only the solitaire, but also other pinyon/juniper dependent birds such as Gray Vireo, Juniper Titmouse, Pinyon Jay, and both species of bluebirds. Although populations of solitaire appear to be stable currently, there is growing concern about the entire suite of birds dependent on pinyon/juniper woodland.

To learn more about Townsend’s Solitaire, including the song and “Tew” call, visit www.birds.cornell.edu Look at the menu bar across the top of the page, and click on Bird Guide. This will bring up a search page where you can enter any North American species. Generally, for each species account, there is an audio clip.

I would like to thank Jerry Oldenettel for providing the photograph for this article, and I look forward to sharing more of his wonderful photographs in the future. You can view more of his nature photos on his website.

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