Bird Photos: Studies: Pine Grosbeaks for comparison
Seward and Hope, AK on the Kenai Peninsula

Jim Pike raised the question on Calbirds about the particular subspecies of Pine Grosbeak that Ken and Brenda Kyle photographed at Galileo Hill on 11/3/04. A photo is posted at Joe Morlan's website. Below are photographs of Pine Grosbeaks that were taken in June in Seward and Hope, AK. Presumably, these are Pinicola enucleator flammula, which breeds from coastal south central Alaska to northwest British Columbia, and maybe P.e. leucurus, which breeds in central Alaska, according to Pyle's Identification Guide to North American Birds, Part I. The location of the Kyles' bird was unusual for this species, so the subspecies is not so obvious. I would guess that leucurus and montanus are also possibilities, based on bill sizes and wintering ranges.

It may be an exercise in futility to try to assess bill sizes from photos and comparing ranges of measurements, but here's a photo for comparison if you're willing. The exposed culmen mentioned below is the length of the top ridge of the upper bill from the edge of the feathering at the base to the tip of the upper bill. There is often a notch of unfeathered area on many passerines that is not apparent from a side view. This can amount to a fraction of to a few millimeters of length. I have not handled or seen Pine Grosbeaks this closely to know if they have this feature. Bill depth is measured at the distal (outermost, forward-end in this case) end of the nares (nostrils). Comparing relative exposed culmen and bill depth measurements can provide an idea of relative proportion of a bill. Pyle provides ranges of measurements for the various subspecies. It may be difficult to assess bill proportions using ranges of sizes that overlap with other subspecies. Although no sample size is given for the bill measurements, the sample sizes for other measurements range from n=10 to n=100. Here's a list of the bill measurements for the different subspecies:

		This bird was photographed in June 2003 near Seward, AK, which would make this most likely P.e. flammula. This subspecies is listed as having an exposed culmen measuring in the range of 14.4-16.4 mm, with a bill depth measured in the range of 10.6-12.7 mm. I should note that, in this shot, the upper bill tip hooks down and extends a bit past the whitish seed hull between the upper and lower bill tips. The nares appears to be the yellow-orange elliptical shape at the base of the upper bill.

This is a male that was photographed the same day, coming to the same feeder as the female, above.

		And, since I have it, this is a rather poor image of what appeared to be a russet form of a female. The russet color is not very obvious in the shot, but I do recall the bird. This was taken in June 2001, a bit further inland at Hope, AK on the Kenai Peninsula. The location may place this with P.e. leucurus, another large-billed form.

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