The beak is longer and more curved, the claws more crooked, and the tail stiffer than in other Synallaxes, and this difference in structure corresponds to a different mode of life. The Striped Spine-tail creeps on the trunk and larger branches of trees, seeking its insect-food in the crevices of the bark, and when seen clinging to the trunk, supported by its tail in a vertical position, with head thrown far back, and progressing upwards by short quick hops, it looks wonderfully like a small Picolaptes with shortened beak. It is very restless, and while searching for insects constantly utters a short, trilling, querulous-sounding note.
It builds an open nest in the fork of a branch, of soft grasses and hair, thickly lined with feathers, and lays four or five pure white eggs.
[198.] SYNALLAXIS ORBIGNII, Reichenb.
(D’ORBIGNY’S SPINE-TAIL.)
Synallaxis orbignii, Scl. et Salv. Nomencl. p. 64; Scl. P. Z. S. 1874, p. 22, et 1879, p. 461; Salvin, Ibis, 1880, p. 358 (Salta). Synallaxis humicola, Burm. La-Plata Reise, ii. p. 468 (Mendoza, Paraná). Synallaxis crassirostris, Leybold, J. f. O. 1865, p. 401. Synallaxis flavigularis, Döring, Exp. al Rio Negro, Zool. p. 45.
Description.—Above pale earthy brown, superciliaries whitish; wing-feathers blackish, the basal part of the secondaries pale chestnut, forming a transverse band; four middle tail-feathers blackish, the lateral pale chestnut; beneath whitish brown; middle of throat pale rufous; under wing-coverts fulvous; bill and feet horn-colour: whole length 6·5 inches, wing 2·2, tail 3·2.
Hab. Bolivia and Argentina.
This Spine-tail has been noticed by various observers in Northern Argentina, and, if we are correct in referring S. flavigularis of Döring to the same species, occurs also in the Rio Negro district.