Looking At Downys in a Whole New Way

Downy Woodpeckers are found throughout the state of Idaho, at almost every elevation and habitat with necessary trees for nesting and foraging. As one travels across the state from west to east there is a noticeable morphological difference in this species, so much so that in 1972 when Thomas Burleigh published his then definitive work, The Birds of Idaho, he assigned two subspecies to the state. One is found throughout the state, from north to south and then east to almost the border with Wyoming. It is near the eastern border, that he designates another subspecies, one then found continuing on all the way to western Nebraska.

Burleigh assigned the subspecies Dendrocopos pubescens parvirostris to the vast majority of the state. The AOU never recognized this subspecies, and while clinal, it is morphologically distinct. Later the Downy Woodpecker was officially renamed on the Family level to Picidae, thus changing its binomial to Picoides pubescens, and in turn designating the race of all Downy Woodpeckers found in Idaho P.p.leucurus. In other words, the current accepted taxonomy gives us only one recognized subspecies which stretches from east of the Cascades through the Great Basin and Rockies and on to western Nebraska.

Regardless of official subspecies recognition or not, we cannot lose sight of the undeniable fact that Burleigh’s statewide parvirostris is visually distinct from the extreme eastern Idaho (though apparently not northern Idaho birds) of leucurus, especially when we are looking at birds near the western border of the state as opposed to those viewed in the east. If I’m losing you, let's just say that the birds of this species which I regularly see around Boise in the southwest look different from birds seen near the eastern border by observers aware of the color and structural differences.

View these photos, making sure to read through the caption explanation under Photo #1:
http://picasaweb.google.com/jhkrueger/DownyWoodpecker

Of interest to some might be a generalization called Bergman’s Rule, which simply stated is that birds of a species are larger from the north and higher, cooler elevations, while smaller from the south and lower, warmer elevations. This understanding is applicable to the seven recognized subspecies of Downy Woodpecker, although size can be a very difficult characteristic to gauge in the field for a species like this.

Downy Woodpeckers have not been shown to be migratory, but there is strong evidence for dispersal of birds during migration times (they would have to return to place of origin to be considered truly migratory, and that has not been shown to be the case). Whether this dispersal, sometimes for very long distances, and not just altitudinally, is in response to food needs and/or changes of season and vegetation, particularly deciduous trees losing their leaves, is also unclear. There are no areas where this bird breeds that it is not also present at any other particular season of the year.

Identifiable specimens of parvirostris have been taken as far north as Bonner County south to Owyhee County. As with Horned Larks, banding data would be interesting and informative to gather from various areas of the state…even examining data already gathered from Idaho Bird Observatory stations in the west and east could make a difference in our understanding… if any such morphological differences were ever noted or photos taken.

Could we possible find other Downy Woodpecker subspecies in Idaho? Reasonable possibilities would be P.p.turati (smaller and paler gray, not immaculate white below as Idaho birds tend to be), which is resident from north central Washington to central Oregon, all east of the Cascades, or P.p.gairdnerii, resident from south west British Columbia to northern California, mainly west of the Cascades (and is actually similar in wing appearance to Burleigh’s parvirostris, with few spots, but with underparts usually a very dingy white, sometimes even a brownish gray).

Confused? Frustrated? Don’t really care? But just think of the upside, the enjoyment, of getting to know this bird, and for that matter any bird, so well. If you’ve come this far with me…and even studied the pictures with their captions, I am willing to bet that you will never look at a Downy Woodpecker in the same way again! And this is a great time of the year to really start looking, because drumming birds are so much easier to locate in spring and early summer.