Distribution and color variation of gyrfalcons in Russia
Journal of Raptor Research
By: D. H. Ellis, Catherine H. Ellis, G.W. Pendleton, A.V. Panteleyev, I.V. Rebrova, and Y.M. Markin
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Abstract
Gyrfalcon (Falco rusticolus) museum specimens in Moscow (73) and St. Petersburg (132) were divided into four color classes (gray, light gray, white gray, and white) and four longitudinal belts representing major physiographic regions of northern Russia. Gray variants predominated in the west and central regions. White birds were most common in extreme eastern Siberia, but were occasionally found even west of the Ural Mountains. Frequencies were as follows: European Russia 4% white, 50% gray (the remainder were intermediates); western Siberia 0% white, 58% gray; central Siberia 15% white, 42% gray; and eastern Siberia 47% white, 33% gray. Remarkably, in the easternmost subregion, white birds predominated even near the southernmost extension. Because the northernmost portions of the species' range in continental Russia are in central Siberia where white variants were rare, we propose that a better predictor of the white variant is longitude, not latitude. White birds were most frequent at the eastern reaches of both the Palearctic and Nearctic. The best environmental correlates of this distribution pattern may be the southward bending thermal isoclines proceeding eastward toward Greenland or Kamchatka, where both land masses are bathed by cold oceanic currents of Arctic origin. By contrast, the western reaches of both land masses are bathed by warm currents. In these western reaches, Gyrfalcon summer distribution is displaced northward and dark variants predominate. The breeding range of the Gyrfalcon, determined by mapping the locations of the specimens we examined, differs little from the range proposed in 1951.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Distribution and color variation of gyrfalcons in Russia |
| Series title | Journal of Raptor Research |
| Volume | 26 |
| Issue | 2 |
| Year Published | 1992 |
| Language | English |
| Contributing office(s) | Patuxent Wildlife Research Center |
| Description | 81-88 |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Raptor Research |
| First page | 81 |
| Last page | 88 |
| Google Analytic Metrics | Metrics page |