Field Identification

The Siberian Nuthatch is immediately recognizable as a nuthatch. It is rather stout overall, with a proportionately large head and short tail. As is true for many nuthatches, it is largely blue-gray above and whitish with some chestnut below. It is larger than most nuthatch species and has a proportionately long bill.

The Siberian Nuthatchis a medium-large nuthatch at ca. 15 cm in length and ca. 20.5 g in mass (1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ). The sexes are inseparable, and the juvenile plumage is undescribed (1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ). The following description is based largely on Red'kin and Konovalova (1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ): The upperparts from the crown through the uppertail coverts are blue-gray. The upper surface of the tail is similarly colored with black lateral edges when folded. Some individuals have a narrow weak pale gray supercilium that, when present, can reach the forehead. Below the supercilium, or adjacent to the crown if there is no supercilium, lies a narrow black eyeline that extends from the base of the upper mandible through the eye and then tapers off as it approaches the posterior auriculars. The chin, throat, auriculars, chest, and center of the belly are snow white. The sides of the belly and the vent are chestnut. The undertail coverts are paler chestnut with white spotting. When viewing the tail from below, the outermost pair of rectrices appear nearly entirely white, the central pair of rectrices are entirely blue-gray, and those in between are black distally and white proximally. The upperwing secondary coverts are blue-gray, similar to the color of the back, without white tips to the greater secondary coverts. The tertials are blue-gray, with blackish on the inner webs. The secondaries are blue gray, and the primaries are dusky to blackish with white tips when fresh. The underwing coverts are blue-gray. The bill is rather long and slender; the culmen is straight while the lower edge of the bill turns sharply upward distally, often imparting a (false) impression that the bill is slightly upturned. Compared to the white-bellied subspecies group of Eurasian Nuthatch (Sitta europaea) (asiatica Group), the Siberian Nuthatch is larger overall and modestly darker above, but it has shorter tarsi and toes with proportionately longer claws, especially the hind claw, which is almost as long as its corresponding toe.

Like many Eurasian nuthatches, the Siberian Nuthatch is blue-gray above, largely white below, and has a black stripe through the eye, and so, it is reminiscent of number of a number of species including Eastern Rock Nuthatch (Sitta tephronota) , Eurasian Nuthatch, Chestnut-vented Nuthatch (Sitta nagaensis), White-tailed Nuthatch (Sitta himalayensis), and White-browed Nuthatch (Sitta victoriae) , but only the Siberian Nuthatch poses a significant identification challenge.

The primary identification challenge for Siberian Nuthatch comes from the Eurasian Nuthatch , especially the white-bellied subspecies group of Eurasian Nuthatch, Sitta europaea asiatica group. Unless specified otherwise, all references to the Eurasian Nuthatch in the section refer to the white-bellied subspecies group. The Siberian Nuthatch differs as follows from the Eurasian Nuthatch: 1) the bill is longer but not thicker, with an absolutely straight culmen (modestly down-curved in Eurasian Nuthatch) and a lower edge of the bill that cuts sharply upward distally; 2) the black eyeline is slimmer and shorter; 3) the pale gray supercilium and forehead are never prominent (as is true in Sitta europaea albifrons and Sitta europaea asiatica) and often absent (as may be true in Sitta europaea baicalensis); 4) the chestnut sides are more extensive; 5) the greater upperwing coverts are never tipped in white (typically present on Eurasian Nuthatch in fresh plumage); 6) the underwing coverts are dark blue-gray (versus whitish in the Eurasian Nuthatch); 7) the inner web of the outermost rectrix is black for approximately its basal third (versus circa 2/3 black in the Eurasian Nuthatch), with less black on the outer web as well, and the extent of black at the tip of the outer rectrix is about half that of the Eurasian Nuthatch, so that, in total, the outer rectrix is about 75% white in the Siberian Nuthatch vs < 50% in Eurasian Nuthatch; 8) probably of use only in hand or in excellent photos, the hind claw is about the same length has the hind toe, whereas the hind claw is about half the length of the toe in Eurasian Nuthatch (2 Eck, S. (1984). Katalog der ornithologischen Sammlung Dr. Udo Bährmanns (3. Fortsetzung). Zoologische Abhandlungen, Mu­seum für Tierkunde Dresden 39:71–98. Close , 3 Harrap, S., and D. Quinn (1995). Chickadees, Tits, Nuthatches & Treecreepers. Princeton University Press, Princeton, NJ, USA. Close , 4 Eck, S. (1996). Die Paläarktischen Vögel — Geospezies und Biospezies. Zoologische Abhandlung 49(Supplement). 103 pp. Close , 1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ).

There are additional morphological differences between the Siberian Nuthatch and the Eurasian Nuthatch that might prove useful in hand or when looking at good photographs. The Siberian Nuthatch is larger than the subspecies of the Eurasian Nuthatch with which it is sympatric or parapatric, with the total length of a male Siberian Nuthatch = 147.97 mm ± 0.52 SE, that of a male Sitta europaea baicalensis = 137.88 mm ± 0.56 SE and that of male Sitta europaea asiatica = 137.31 mm ± 0.47 SE. Similarly, the mass of male Siberian Nuthatch is 21.21 g ± 0.47 SE, while that of male Sitta europaea baicalensis is 18.69 g ± 0.20 SE and that of male Sitta europaea asiatica is 18.37 g ± 0.35 SE (1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ). Additionally, most of the added bill length in the Siberian Nuthatch is distal to the nostrils, so that the ratio of bill length past nostrils to total culmen length is 0.86–0.93 in the Siberian Nuthatch but 0.6–0.7 in Sitta europaea baicalensis and 0.60–0.76 across all subspecies of Eurasian Nuthatch (5 Dunajewski, A. (1934). Die eurasiatischen Formen der Gattung Sitta Linn. Acta Orn. Mus. Zool. Polonici 1: 181-251. In German. Close ). The wings of the Siberian Nuthatch are stated as being more pointed than those of the Eurasian Nuthatch due to the penultimate primary, p9, being equal in length to p4 in the Siberian Nuthatch and longer than p4 in the Eurasian Nuthatch (3 Harrap, S., and D. Quinn (1995). Chickadees, Tits, Nuthatches & Treecreepers. Princeton University Press, Princeton, NJ, USA. Close , 1 Red’kin, Y., and M. Konovalova (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zoologische Mededelingen Leiden 80(5):241–261. Close ). Yet, if p9 is relatively short compared to p4, the wing should be more rounded, not more pointed; more study is needed to define this character.

Perhaps the most distinctive difference between these two species is in their vocalizations (6 Leonovich, V.V., Demina, G.V. and Veprintseva, O.D. (1996). [Sitta europaea L. and “small” nuthatches S. villosa Verreaux and S. krueperi Pelzeln: problems of taxonomy and phylogeny]. Byull. Mosk. Ova. Ispyt. Prir. Otd. Biol. 101(1): 37–49. In Russian with English summary. Close ). Though available recordings of the Siberian Nuthatch calls are limited, the calls of adults could be described as a plaintive yuuuuu that tapers off in volume and frequency towards the end (xeno-canto XC675326), a whistled taweeeo that is roughly 3 kHz at the beginning and end and at 3.5 kHz in the middle (xento-canto XC676024), and a raspy alarm twitter (xento-canto XC675325), which–except for the twitter–differ markedly from any call described for Eurasian Nuthatch by Harrap and Quinn (7 Harrap, S., and D. Quinn (1996). Tits, Nuthatches & Treecreepers. Christopher Helm, London, UK. Close ). Additionally, calls of Sitta europaea asiatica, S. e. amurensis, and S. e. baicalensis surveyed on xeno-canto included an upslurred shrill wheeeet (xeno-canto XC120469), a tweet-tweet-tweet-tweet (xeno-canto XC355897), a wee-wee-wee-wee (xeno-canto XC162526), and a rapid jip-jip-jip-jip, the latter given during an agitated response to an owl tape (xento-canto XC457086), none of which resembled the vocalizations of the Siberian Nuthatch.