Page:The Fauna of British India, including Ceylon and Burma (Birds Vol 1).djvu/51

This page has been validated.
19
CORVIDÆ.

Choughs. All species are resident within the limits of this work except the Rook and the Hooded Crow, which are winter visitors to the North and North-West. Their summer quarters are, however, not far off and their migrations are only partial and local. The members of the genera Corvus, or the true Crows, Pica, the Magpies, Nucifraga, the Nutcrackers, and Pyrrhocorax, the Choughs, are birds of wide distribution but the members of the other genera are nearly all restricted to small areas.

The Corvidæ vary a good deal inter se in structure and habit. In one or two genera the nostrils are not so completely hidden by bristles as in the typical Crow. The majority feed completely on the ground, others are strictly arboreal. They all agree in laying four or five spotted eggs except certain species of the genus Podoces, which lay white eggs in burrows. The mode of nidification of the remaining genera varies greatly, some species breeding in holes of trees and cliffs, the others, the majority, constructing large nests of sticks and twigs. Most of them are omnivorous, but some of the smaller tropical species appear to confine their diet to insects.

The Corvidæ, as a family, have few characters in common, and yet there is no group of birds which is more easily recognized.

Key to Genera.

A.
Nostrils distant from forehead about one-third length of bill; narial bristles rigid and straight, reaching to about middle of bill; or rictal bristles and feathers of face absent.
a.
Tail much shorter than wing
....................................................................................................................................................................................................................................................
Corvus, p. 20.
b.
Tail much longer than wing
....................................................................................................................................................................................................................................................
Pica, p. 37.
B.
Nostrils distant from forehead less than one-quarter length of bill; narial bristles or plumes short, never reaching to middle of bill.
c.
Tail greatly graduated, outer feathers less than half length of tail.
a’.
Middle tail-feathers uniformly wide throughout or widening gradually towards tip.
a’’.
Bill red or yellow.
a’’’.
Tail more than twice length of wing
....................................................................................................................................................................................................................................................
Urocissa, p. 40.
b’’’.
Tail less than twice length of wing
....................................................................................................................................................................................................................................................
Cissa, p. 45.
b’’.
Bill black
....................................................................................................................................................................................................................................................
Dendrocitta, p. 47.
b’.
Middle tail-feathers suddenly broadening towards tip
....................................................................................................................................................................................................................................................
Crypsirhina, p. 56.
d.
Tail not much graduated, outer feathers more than half length of tail.
c’.
Graduation of closed tail less than length of tarsus; rictal bristles extremely long
....................................................................................................................................................................................................................................................
Platysmurus, p. 58.