Fox Sparrow

My English war bride aunt has a charming way of calling any small, hard to identify bird a “dickie bird”. Finch, sparrow, wren, warbler – they are all dickie birds. Occasionally as I struggle to identify one of those cryptically patterned birds, I begin to think maybe Aunt Doreen has the right idea after all.

A third bird foraging along the shore of Eagle Lake (Lassen County CA) on my last visit is the fox sparrow (Passerella iliaca). Leonard and I did not agree on this sparrow’s species, thus I held off posting until we could do further research.

The plumage of a fox sparrow is highly variable  with the upper parts ranging from dark brown or gray brown in the west to rufous coloration in the east. There are four distinct subspecies based on plumage traits, range and voice. Some authorities classify these subspecies as distinct species. These fox sparrows are most likely the “sooty” subspecies with their gray heads, but could be “slate colored”. I am simply going to be like my aunt and not get too particular about their identification. Fox sparrow is close enough. This sparrow gets its common name from its rich red coloration (eastern subspecies) that resembles a red fox pelage.

The buff or white underside of a fox sparrow is heavily streaked converging at mid breast in a large dark spot. Some guides describe the streaks as triangular. Large for a sparrow, fox sparrows have a heavy, thick based bill that is dark on the upper mandible and yellow on the lower mandible. The tail is slightly notched. Both sexes look similar.

The preferred habitat of fox sparrows is thickets, edges of coniferous or mixed forests or chaparral. Here they forage by scratching along the ground or digging small holes by kicking backward with their feet. Fox sparrows resemble spotted towhees in the way they search for the seeds, fruits, berries, insects, spiders, small snails and millipedes that comprise their diet.

Fox sparrows breed and summer from the Aleutians and mainland Alaska east to Northern Quebec and the Maritimes and south to California and Colorado. Short distance migrants, they winter in the Pacific Coast states and British Columbia as well as the southern states. Although they are solitary while raising their families, fox sparrows form small flocks outside of the breeding season.

Merlins, Stellar’s jays and other predatory birds will take fox sparrows. When their eggs or chicks are threatened by weasels, chipmunks or snakes, fox sparrows will attempt to divert the predator by using the “broken wing display” commonly employed by killdeer.

I read a comment that fox sparrows were discovered in fossils from the Pleistocene (11,000 years ago) in Pennsylvania, Virginia and the La Brea Tar Pits (CA). Curious, I found a paper by William R. Dayson published in a 1948 issue of “The Condor”. There Dayson describes the birds he found in the La Brea Tar Pits using the birds’ fossilized mandibles. He identified all these different bird species, including fox sparrows, using only the differences in their tiny bills. Wow! That boggled my mind! I had difficulty identifying a fox sparrow with pictures and actually seeing the bird, and here was this scientist who identified the same bird with only a fossilized mandible. Impressive!!

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