The
grey crowned crane (
Balearica regulorum) is a
bird in the
crane family,
Gruidae. It is found in eastern and southern Africa, and is the national bird of Uganda.
Taxonomy
The grey crowned crane is closely related to the
black crowned crane,
and the two species have sometimes been treated as the same species.
The two are separable on the basis of genetic evidence, calls, plumage
and bare parts, and all authorities treat them as different species
today.
[2]
There are two
subspecies. The East African
B. r. gibbericeps (crested crane) occurs in the east of the
Democratic Republic of the Congo and in
Uganda, of which it is the national bird represented in its
national flag, and
Kenya to eastern
South Africa. It has a larger area of bare red facial skin above the white patch than the smaller nominate species,
B. r. regulorum (South African crowned crane), which breeds from
Angola south to South Africa.
Description
The grey crowned crane is about 1 m (3.3 ft) tall, weighs 3.5 kg (7.7 lbs), and has a wingspan of 2 m (6.5 ft). Its body
plumage
is mainly grey. The wings are predominantly white, but contain feathers
with a range of colours, with a distinctive black patch at the very
top. The head has a crown of stiff golden
feathers. The sides of the face are white, and there is a bright red inflatable
throat pouch. The
bill
is relatively short and grey, and the legs are black. They have long
legs for wading through the grasses. The feet are large, yet slender,
adapted for balance rather than defence or grasping. The sexes are
similar, although males tend to be slightly larger. Young birds are
greyer than adults, with a feathered
buff face.
This species and the black-crowned crane are the only cranes that can
roost in trees, because of a long hind toe that can grasp branches.
This trait is assumed to be an
ancestral trait
among the cranes, which has been lost in the other subfamily. Crowned
cranes also lack a coiled trachea and have loose plumage compared to the
other cranes.
[3]
Distribution and habitat
It occurs in dry savannah in
Africa south of the
Sahara, although it nests in somewhat wetter
habitats.
They can also be found in marshes, cultivated lands and grassy
flatlands near rivers and lakes in Uganda and Kenya and as far south as
South Africa. This animal does not have set
migration
patterns, and birds nearer the tropics are typically sedentary. Birds
in more arid areas, particularly Namibia, make localised seasonal
movements during drier periods.
[2]
Behavior
The
grey crowned crane has a breeding display involving dancing, bowing, and
jumping. It has a booming call which involves inflation of the red
gular sac.
It also makes a honking sound quite different from the trumpeting of
other crane species. Both sexes dance, and immature birds join the
adults. Dancing is an integral part of courtship, but also may be done
at any time of the year.
Flocks of 30-150 birds are not uncommon.
Diet and feeding
These cranes are omnivores, eating
plants, seeds, grain,
insects,
frogs,
worms,
snakes,
small fish and the eggs of aquatic animals. Stamping their feet as they
walk, they flush out insects which are quickly caught and eaten. The
birds also associate with grazing herbivores, benefiting from the
ability to grab prey items disturbed by
antelopes and
gazelles. They spend their entire day looking for food. At night, the crowned crane spends its time in the trees sleeping and resting.
Breeding
Eggs of
Balearica regulorum gibbericeps at the
MHNT
Grey crowned cranes time their breeding season around the rains,
although the effect varies geographically. In East Africa the species
breeds year-round, but most frequently during the drier periods, whereas
in Southern Africa the breeding season is timed to coincide with the
rains.
[2] During the breeding season, pairs of cranes construct a large
nest; a platform of
grass and other plants in tall wetland vegetation. The grey crowned crane lays a clutch of 2-5 glossy, dirty-white
eggs, which are incubated by both sexes for 28–31 days. Chicks are
precocial, can run as soon as they hatch, and fledge in 56–100 days.
Relationship with humans
Status and conservation
Although the grey crowned crane remains common over some of its
range, it faces threats to its habitat due to
drainage,
overgrazing, and
pesticide pollution. Their global population is estimated to be between 58,000 and 77,000 individuals. In 2012 it was uplisted from
vulnerable to
endangered by the
IUCN.
[4]
Symbolism
The grey crowned crane is the national bird of
Uganda and features in the country's
flag and
coat of arms.
[5]
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