Thursday, April 28, 2016

House Wren at Dixon Lake

House Wrens are quite common in San Diego County throughout the year. It is unknown, however, how many of the numerous wintering birds may migrate north to breed. Do any of the birds that spend the winter here stay and breed here in the summer, or do the breeding birds winter elsewhere?

House Wren
House Wren. Dixon Lake, Escondido, California. April 15, 2016. Greg Gillson.
House Wrens are most abundant in summer in coast live oak and also sycamore woodlands from sea level to highest mountains. In recent decades they have increased into residential areas for which they were named, as has been the case in the eastern half of the continent. Nesting records confirm that House Wrens breed an average of 2 weeks earlier now than a century ago, signaling a response to climate change (San Diego County Bird Atlas. Unitt. 2004).

The lively bubbling song begins with a distinctive harsh "churr" note.

House Wren

Winter birds are most common in coastal lowlands. Their wide variety of short harsh calls can sound like the calls of California Gnatcatchers and Ruby-crowned Kinglets that share the same winter habitat. I'm inclined to view this as mimicry rather than coincidence--even though calls in songbirds are generally hard-wired and immutable, while songs are learned while young.