The Collaborative International Dictionary of English v.0.48:

Nuthatch \Nut"hatch`\, n. [OE. nuthake. See 2d Hack.] (Zool.)
   Any one of several species of birds of the genus Sitta, as
   the European species (Sitta Europaea). The white-breasted
   nuthatch (Sitta Carolinensis), the red-breasted nuthatch
   (Sitta Canadensis), the pygmy nuthatch (Sitta pygmaea),
   and others, are American.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Sitta canadensis
    n 1: bluish-grey nuthatch with reddish breast; of northern
         coniferous forests [syn: red-breasted nuthatch, Sitta
         canadensis]