Sunday, April 15, 2012

Bushtit

Like the Wrentit, Bushtits enjoy a confusing taxonomy. At first these common, non-migratory western birds were thought to be in chickadee and titmouse family, Paridae. Furthermore, Bushtits with black or plain ear auriculars (ear coverts) were thought to be distinct species (named Black-eared and Plain bushtits, depending on the color). Ornithologists discovered that ear color was polymorphic, some birds out of the same nests had black ears and others plain-colored ones. The farther south you travel, the more you encounter black-eared birds. Males are more often black-eared than are females. Almost all northern birds, like the one in my photo from the Kate Sessions Park in San Diego, are plain-eared.

DNA research makes the surprising conclusion that Bushtits are the sole representative in the New World of an Old World family, Long-tailed Tits, Aegithalidae. Long-tailed Tits have only recently been moved from the Paridae (titmice, etc.) into Aegithalidae.

Whatever their evolutionary history might be, Bushtits are easy to find in the west. They can form large flocks and often move about with other species.  We found this Bushtit in the company of the Wrentits of the previous post.They prefer oak, pine, and coastal shrub-lands. Their feeding behavior is often similar to chickadees. Bushtits are also interesting because they will often help other pairs raise young--these helpers can be male, female, juvenile, or adult. The helpers are not necessarily related to the nesting pair they assist. But, to complicate matters, Bushtits of both sexes may take on multiple mates (Sloane 2001).

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