Breeding Fox Sparrows in the southern Cascades of Washington
Washington Fox Sparrow (Passerella iliaca olivacea)
All well and good... until the Oregon Breeding Bird Atlas (1995-1999) found Fox Sparrows north in the Oregon Cascades nearly to the Columbia River. On July 14, 2001 I explored higher clear cuts and found apparent Thick-billed Fox Sparrows (P. I. megaryncha/fulva) at 1945 feet and 2718 feet along Kingsley Guard Station Road near Green Point Upper Reservoir, Hood River County, 11 miles SW, and across the Columbia River, from White Salmon, Klickitat County, Washington. The birds I saw were 5 miles directly south of Cook, Skamania County, Washington. They were brownish overall, with plain gray faces, typical of megaryncha/fulva. However, they were more heavily marked below than most, with the spots forming streaks on the sides and flanks and coalescing into a central breast spot. Underpart streaking in this form (fulva) is known to vary widely within short distances. The red was restricted to the rump. The bill appeared large and it gave a White-crowned Sparrow-like "tsip" call, typical of Thick-billed and unlike the "chip" or "chep" of the Slate-colored group.
Independently, Wilson Cady observed Fox Sparrows he suspected were Thick-billed on the Klickitat/Skamania County line on the Monte Carlo Mountain Range, about 10 miles north of Cook, Washington in 1998. Cady learned that Bill Tweit had seen probable Thick-billed Fox Sparrows on Stacker Butte, Klickitat County, above Dallesport. On July 13, 2003 just east of the intersection of 6610 Road and 8631 Road, Cady found several birds in Skamania County, which matched the description of Thick-billed Fox Sparrows. The underparts were lightly marked with small spots, head marked with gray, tail reddish.
This puts the Thick-billed Fox Sparrow (P. i. megaryncha/fulva) into Washington and into the range described to be Slate-colored Fox Sparrow (P. i. olivacea).
Fox Sparrow subspecies can be difficult to separate, especially between the Thick-billed and Slate-colored, which some consider to be one group rather than two. Such similar forms can merge into one another where their ranges meet. However, there are some obvious differences in plumage and calls of the observed birds.
Note this olivacea above, photographed by Ruth and Patrick Sullivan at White Pass, Yakima County, Washington, near Mt. Rainier, in May 2000. This bird is very gray on the entire head, back, scapulars, and rump. They entire tail is foxy red, and the wings are reddish-brown. Note the large dark brown triangle-shaped breast spots all forming long streaks, starting at the throat. Also note that the upper mandible is much taller at the base than is the lower mandible.
On the other hand, this megarhyncha/fulva photographed above in Marion County, in the northern Oregon Cascades, by Steve Dowlan is much browner overall. The crown is brownish-gray, and the sides of the head are grayer. Note especially the tiny black inverted chevrons widely speckled across the underparts.
The bird above was photographed at Lava Lake, Linn County, Oregon by Greg Gillson. Note that the tail and wing, including scapulars, are brownish. There is some rusty in the secondary wing edgings and rump. Again, the crown is rather brownish in contrast with the gray sides of neck. The breast spots are widely scattered. The lower mandible is nearly as tall as the upper mandible (this is not what "thick-billed" means, though. Thick refers to width, side to side at the gape, which is a difficult thing to see and compare in field observations.).
I will warn, however, that I have seen a few individuals of megaryncha/fulva that are quite gray above, with no brown mixed in. However, these still are sparsely peppered with small breast spots. In addition, the wings and tail are brown, with rusty restricted to the rump.
Questions: Have Thick-billed Fox Sparrows replaced Slate-colored Fox Sparrows in the southern Cascades of Washington within the last 50 years? Do both Thick-billed and Slate-colored occur? Or, do they gradually merge into each other? Or, are we fooling ourselves, thinking we can separate these subspecies by sight and calls?
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