Black-necked Crane - WWF-India

is often used to signal exchange
of duties at the nest. When either
parent suspects danger, it utters
a warning call, which precipitates
their departure. The oval shaped
eggs vary in size according to the
species. The smallest crane, the
Demoiselle, has eggs equal to the
volume of perhaps three chicken
eggs, while the larger cranes such
as the Sarus and the Wattled have
eggs more than double that size.
The colour of the eggs also vary.
Crowned Crane eggs are usually
light blue in colour, the small cranes
of the Gruinae genus produce dark
and heavily pigmented eggs, and
the larger cranes usually lay lightly
pigmented or white eggs.
Crane chicks remain with their
parents throughout winter, and
stay with them for part or all of
the journey back to the northern
latitudes. However, as the sexual
cycle of the adults begins anew,
the juveniles are driven away, often
forcibly. A pair redefi nes its breeding
territory, while the yearling birds join
the other non-breeding birds in the
fl ock. In their second
spring, the young birds begin to
exhibit sexual behaviour. Pairing and
nesting usually occur in the third or
fourth year.
In autumn, the cranes from the
northern latitudes gather in fl ocks.
Then, at mid-morning, on a clear
day with a southerly wind blowing,
the cranes begin to spiral skywards
and head south, beginning their
long migration. Continually emitting
loud calls, which presumably helps
to keep the fl ock together, they fl y
through the day in a ‘V’ formation
or in a line, sometimes at altitudes
over 18,000 feet. The chicks remain
beside their parents and must
remember the landmarks below to
follow in the years to come.
Late in the day, the fl ock descends
to roost at an available wetland,
Second egg still under incubation
where they rest for the night.
Weather permitting, they continue
their journey the next morning.
Some of these resting areas are
randomly visited by the cranes
and other wetlands are traditionally
used as staging areas and host the
migrating cranes for several weeks.
For example, Lake Ab-i-Estada in
Afghanistan is an important staging
area for the Siberian Crane which
used to migrate over the Hindu-
Kush mountains in their long journey
between breeding grounds on
the arctic tundras and wintering
wetlands within the Keoladeo
National Park in India. Unlike many
other birds, their fl ight paths are
regular and rigidly defi ned, so that
fl ocks are sighted every year over
the same regions. But in fi ne, clear
weather the cranes tend to soar
to such altitudes that it is almost
impossible to see them with the
naked eye! Only their harsh, strident
cries betray their presence and
position. When a large fl ock is fl ying
in formation, its progress appears
to be wavering and somewhat
unorganized. But more frequently
the cranes split up into smaller
groups of ten to fi fteen individuals,
arranged in neat V-shaped
formation, following one another
closely.
Some ornithologists believe that
the geometrical formations adopted
by the cranes in fl ight save energy,
because only the leader of each
group is obliged to battle against
wind resistance, the others taking
the advantage of the draught
produced by the wing beats of
the birds ahead of them. It is
noticeable, for example, that the
leading bird is replaced at regular
intervals by other members of the
fl ock, allowing it some respite.
This theory fi nds support from the
fi eld of aeronautics, for it has been
established that a squadron of
planes in formation use much less
fuel than planes fl ying separately or
in a straight line (Allan 1998).
During winter, cranes
live in groups near ponds, lakes and
arable land. While feeding on grains
and vegetation, one or two
individuals keep watch and at the
fi rst signal of alarm the whole colony
takes to air.
Distribution
Cranes are found on all continents
of the world, except South America
and Antarctica. Asia boasts
the highest diversity, with eight
breeding species. Two of these,
the Demoiselle and Eurasian
Ladakh Region India | 2000-2004 11