388 CoLUMB^. BIRDS. C0LUMBID.E. 
believed that when the birds found it impossible to get 
access to the combs by their own exertions, they would 
set off in search of human aid, and guide their allies to 
the hive by flying before them from bush to bush. The 
Ilottentots are said always to leave a portion of comb 
for the Honey Guides when they have been led by 
them to the discoveiy of a hive. A peculiar mammal, 
the Ratel, which is as partial to honey and the other 
contents of the hive as the Honey Guides themselves, 
also avails himself of the instinct of these birds, and 
is often conducted to a rich banquet by their cries. 
The Honey Guides fly heavily, and only for short dis- 
tances, but they run upon the trunks and branches of 
trees with great agility in the manner of the Wood- 
peckers, to which Mr. Blyth considers them as more 
nearly allied than to the Cuckoos. Their mode of 
breeding has long been a matter of dispute — some 
ornithologists asserting that they deposit their eggs in 
holes of trees, and others that they form a pensile nest ; 
but, from the observations of M. Verreaux, it would 
appear that they have the parasitic habits of the common 
Cuckoo, introducing their eggs sometimes into the nests 
of Woodpeckers, and sometimes into those of Orioles, 
which would account for the discrepancy in the state- 
ments above alluded to. The species are principally 
found in Africa, and indeed in the southern parts of 
that continent, but one or two occur in the forests of 
India, and in the island of Borneo. 
Order IV.— COLUMBiE. 
The Order of the Columbae or Pigeons stands as it were 
in an intermediate position between the Passerine birds 
and the Galllnee, between the two sections of Inses- 
sores and Autophagm, into which, as already stated 
(p. 235), the class of birds has been divided. With the 
former theyagree in their nidification and in the help- 
lessness of their young, which remain in the nest for a 
considerable time, and require to be carefully tended 
and fed by the parent birds ; whilst they approach the 
latter to a considerable extent in their structure. In- 
deed, by some ornithologists the Columbae are amal- 
gamated with the gallinaceous birds to Ibrm a single 
order. There is, however, one important peculiarity 
which seems to distinguish the Pigeons from all birds ; 
the walls of that dilatation of the oesophagus which 
usually goes by the name of the crop, are furnished 
with a number of glands, from which during the breeding 
season a milky juice exudes; this mingles with the 
food in the crop, soaks into it and softens it, so that, as 
the young birds are fed with substances regurgitated 
from the crops of their parents, they may be regarded 
as partially nourished by a secretion produced by the 
latter, just as the young Mammals are supported upon 
their mother’s milk. 
The principal distinctive character of the Columbse 
is furnished by the structure of the bill. The upper 
mandible consists of a hornj' apical portion, which is 
often of considerable length and strength, but its base 
is formed by a convex cartilaginous plate, in the ante- 
rior portion of which the nostrils are situated. The 
skin covering the cartilaginous portion of the bill is of 
a soft texture, very different from that of the rest of the 
bill ; it is sometimes smooth and clothed with a sort of 
scurf, but in other cases it is warty, or even developed 
into a fleshy wattle. This is especially the case in 
some domesticated varieties of the pigeon. 
The Columbae are provided with short tarsi and 
moderately long toes, all scutellated. The toes are four 
in number, three in front and one behind ; the anterior 
toes are not united by a membrane at their base ; the 
hinder toe is placed in the same plane as the anterior 
toes, and the whole sole of the foot is formed by soft 
papillated pads, which are usually a good deal wider 
than the scutellated upper portion of the toes. The 
wings, which are generally long and pointed, contain 
ten primary quills, and the tail usually consists of 
twelve feathers, although in some cases there are six- 
teen. An important distinctive character of the birds 
of this order as compared with the Gallinse, is to be 
found in the fact that their feathers are destitute of the 
plumules or accessory plumes (p. 232), which are greatly 
developed in the gallinaceous birds. 
The form of the wings in the Pigeons is sufficient to 
indicate that they are birds of rapid and powerful flight, 
and mariy of them are remarkable for the speed with 
which they traverse the air, especially when engaged 
in those migrations which some species perform. Most 
of them are arboreal in their habits, and nestle in the 
holes of trees ; others frequent rocks ; but all perch 
with great facility, although they generally seek their 
food upon the ground, and walk or run with consider- 
able ease. They are also remarkable in their mode of 
drinking, in which they differ from all other known 
birds. The general practice of birds in drinking is, as 
is well-known, to take up a small portion of water in 
the bill, and then, by raising the head, to allow it to 
flow down into the throat; the Pigeons, on the con- 
trary, dip their bills into the water and hold them there 
until they have quenched their thirst. 
In Mr. Gray’s arrangement the Pigeons form only a 
single family, that of the Columbidm ; and as the birds 
all exhibit a very close resemblance to each other, we 
may follow his example in this respect, merely separat- 
ing the species into certain subordinate groups which 
appear to be indicated by peculiar characters. These 
birds are inhabitants of the warmer and temperate 
regions of the earth, but they are found in most abun- 
dance in hot climates, where also their plumage attains 
a bi'illiancy of which that of our native species gives 
us no idea. 
Family I.— COLUMBIDZE. 
Pigeons. 
The section of the True Pigem^s, to which our British 
species of this groiq.) belong, may be regarded as the 
most typical of the order. The birds of this section 
1 have a rather small and slender bill, the base of which 
