Bill hard and horny, never extensively membranous, softly tumid, nor
cered; nostrils without open communication; greater wing-coverts not
more than one-half the length of the secondaries; primaries usually
ten, more rarely nine; rectrices twelve, rarely ten; feet adapted
for perching; hind toe and claw well developed and inserted on the
level of the anterior toes; hind claw equal to, or longer than, the
claw of middle toe; anterior toes three in number, never versatile,
always free except when webbed or fused at base.
The order Passeriformes includes nearly as many species, among
Philippine birds, as all the other orders combined. Most of the species
of this order are less than 200, and very few of them are more than
300, millimeters in length. The small birds belonging to other orders
are extremely few. Most ornithologists consider the Passeriformes
to be the order of highest rank among birds, chiefly because of
the highly developed vocal powers of many of the species. In the
arrangement of the families of this order, the Turdidæ, Fringillidæ,
and Corvidæ have variously been assigned to the place indicating the
highest development.