246 BLACK-BACKED THREE-TOED WOODPECKER. 



Nestling male. Similar to the adult but with the yellow on the head more restricted and the black on the back is dull- 

 er, while a few feathers in the interscapular region are spotted with white. 



Nestling female. Similar to the adult but, singularly, the top of the head is spotted with yellow. Descriptions of the 

 last two plumages are from specimens in the collection of Mr Brewster. Iris, brown, bill, black, bluish at base of lower 

 mandible, and feet, bluish, in all stages. 



OBSERVATIONS. 



There is more black spotting below in some specimens than in others hut they are generally quite uniform in color. 

 Readily known from other Woodpeckers by the absence of any red on the head which is replaced by yellow. Known from the 

 succeeding species, by the absence of the transverse white bandings above. Distributed, as a constant resident, through- 

 out North America from the latitude of Maine to the Arctic Circle. 



DIMENSIONS. 



Average measurements of specimens from the North. Length, 9-50; stretch. 15 50; wing, 5-00; tail, 3-70; bill, 1'25; 

 tarsus, '70. Longest specimen, lO'OO; greatest extent of wing, IG'OO; longest wing, .V50: tail, 3-82; bill, 1'30; tarsus, -75. 

 Shortest specimen, 9'00; smallest extent of wing, 15'OD; shortest wing, 4'50; tail, 3'75; bill, T20; tarsus, '65. 



DESCRIPTION OF NESTS AND EGGS. 



Nests, placed in cylinder-shaped holes, generally excavated in living trees. Dimensions, diameter of external orifice, 

 1-50, greatest internal, 3-00. Internal depth, 15'00. 



Eggs, four to six in number, rather ovate in form, pure, polished pearly-white in color. Dimensions from '60x '75 to 

 65x-80. 



HABITS. 



The mere mention of the Three-toed Woodpeckers recalls to my mind the snow-clad 

 mountains and dark evergreen forests of Northern New England, for it was among them, 

 that I first became acquainted with these singular birds. The Black-backed Three-toed 

 Woodpeckers appear to be quite uncommon, even in winter, in these boreal climes, where 

 the sharp cries of the Downy and Hairy are quite frequently heard and, occasionally, the 

 louder notes of the Pileated greets the ear, but one may travel for days, over snow-covered 

 ground, beneath the frozen branches of the pines and spruces, without hearing the discor- 

 dant sounds produced by this rare Woodpecker. 



These Woodpeckers, like many other members of the family, are only migratory to a 

 limited extent; thus, during unusually severe winters, they may occasionally reach Mass- 

 achusetts in their southward flight, but they are exceedingly rare and I know of but two 

 or three instances on record of their having been taken here. These Woodpeckers agree 

 in general habits quite closely with the members of the preceding genus; their flight is 

 similar and in climbing, they are as expert as any of the other Woodpeckers; three toes on 

 each foot appearing to answer as well for clinging to the bark as four. It is difficult to ac- 

 count for the absence' of the hind toe as this apparent mutilation does not impede the move- 

 ments of the birds in the least, yet it is, perhaps, singular that we do not find more species 

 without it, for, as a rule, any superfluity in nature, not ornamental, is almost invariably 

 discarded. 



The nesting habits of this rare specis of Woodpecker are not well known but they 

 are said to build in living trees, probably about the same time as the Hairy or Downy. 

 They are a little more northern in distribution during the breeding season than the suc- 

 ceeding species. 



