Abstract
Doves in the Wild
Pigeons and doves belong to the
avian order Columbiformes and, with
the exception of the polar regions,
they inhabit almost every comer of the
earth, though the "headquarters" of
the group seems to be the Oriental
and Australasian regions. There is no
particular scientific basis for the separation
of the words "pigeon" and
"dove" though the former is often colloquially
applied to the domestic and
larger species, the latter to the smaller
species. Of the 305 or so described
living species, size varies from little
larger than a sparrow to larger than an
average domestic hen. There are
small, dainty seed eaters and plump,
robust fruit eaters. However, all doves
have many anatomical features in
common and the group is quite homogenous.
Looking generally at a dove, for
example, the head is relatively small
in relation to the body. The beak is
also relatively small, short, narrow,
and slightly bent down at the tip. The
soft, sensitive, fleshy cere at the base
of the bill is devoid of feathers. Only
in the fruit eating doves are the
nostrils in the cere wide open and easily
visible. The legs and feet usually
have three forward, sturdy toes and
one smaller hind toe each provided
with short, strong nails. The legs and
feet are usually clearly scaled. In general,
doves are either long and slender
or short and plump, depending on the
natural habitat. Various dove species
possess so-called powder feathers.
With the beak and the head, they
cover their outer feathers with a very
thin layer of protective powder. All
doves have a well developed crop,
but the gall bladder is absent; the
appendix is rudimentary or altogether
absent.
The choice of habitat varies from
species to species, ranging from
dense, tropical rainforest to dry, arid
desert or the temperate regions of
Europe, Asia and North America.
The range of colors is also quite
remarkable: from milky white with
black tipped flight and tail feathers
(Nutmeg Pigeon, Ducula bicolor) to
blue-gray and white with a striking
red breast-patch (Bleeding-heart
Dove, (Gallicolumba luzonica). Various
species are extremely attractive in
their pastel or metallic shades of gray,
fawn, blue, pink, green and yellow.
In spite of these variations, all
species have many characteristics in
common. The whirring sound of the
wings on takeoff is a trademark of all
doves, as is their ability to suck up
water through their short beaks in a
long draft, rather than scooping and
throwing their heads back as most
other birds do.
Doves feed largely on seeds, berries
and other fruits, green leaves and
shoots, spiders and various insects.
They often travel great distances foraging
for food for their young. The
green pigeons (Treronidae) and the
fruit eating doves (Duculidae) (which
are seldom kept in captivity), are
wholly specialized in eating fruits and
berries, while the tropical ground
doves (Gallicolomba), to which the
Bleeding-heart Dove (G. luzonica)
belongs, forage for insects, spiders,
worms, slugs and other invertebrates
on the forest floor. The consumed
food accumulates in the crop, a part of
the alimentary canal that, in doves,
forms a double sack. The main func
tion of the crop is food storage but it is
probable that pre-digestion also takes
place here. During the breeding period
when young are being reared, a
nourishing material is produced by
rupture of the surface cells of the crop
lining. This so-called "crop milk" is
essential for the rearing of the youngsters.
Doves possess two stomaches; a
fore stomach or proventriculus, and a
muscular stomach or gizzard (or ventriculus).
The gizzard grinds up the
harder seeds with the help of grit. The
fruit eating species have a specially
developed digestive tract in which the
fore stomach is extremely large, the
gizzard thinly walled and the intestines
relatively short.
Pigeons and doves are fairly muscular,
and thickly covered with a coat of
feathers that, however, are loosely
attached in the skin. The base of the
feathers is downy to provide good
insulation. Unlike many birds, doves
do not tuck the head under the wing
when resting, but pull it down
between the shoulders.
All members of the Columbiformes
are monogamous which is to say that
they mate for life and remain true to
their mates unless they are separated
permanently by some unforeseen
event. Their flimsy nests consist of a
platform fashioned from a few twigs
placed loosely among the branches of
a tree or shrub, or on a rocky ledge. In
most cases, the clutch consists of just
two eggs, sometimes only one. The
eggs are usually a glossy white, but a
few species lay tinted (brownish)
eggs. In most species, both cock and
hen share in nest-building and incubation,
but the hen usually performing
most of the latter. The time of incubation
varies from 13 to 19 days. The
hatchlings are blind and naked and
are fed by the parent birds on a special
diet known as "pigeon or crop
milk" which consists of a mixture of
partially digested food and a curd-like
secretion from the crop lining (the
dove's crop lining thickens during
incubation). It takes 12 to 20 days for
the young to develop sufficiently for
fledging.