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Grant's Gazelle

Grant's gazelles resemble Thomson's gazelles, and the two species
are often seen together. They are similarly colored and marked, but
Grant's are noticeably larger than Thomson's and easily distinguished
by the broad white patch on the rump that extends upward, beyond the
tail and onto the back. The white patch on the Thomson's gazelle stops
at the tail. Some varieties of Grant's have a black stripe on each side
of the body like the Thomson's gazelle; in others the stripe is very
light or absent. A black stripe runs down the thigh.
Physical Characteristics
The various types of Grant's gazelle differ mainly in color and in
the size and shape of the horns. Grant's are large, pale, fawn-colored
gazelles with long legs. The males are larger and heavier and their
horns longer than the females.
The lyre-shaped horns are stout at the base, clearly ringed
and measuring from 18 to 32 inches long. The width of the spaces
between the horns and the angles of growth differ among the various
types of Grant's gazelles. One type, in northwest Tanzania, has widely
diverging horns, with the tips directed downwards.
On the females black skin surrounds the teats, with white hair
on the udder. This probably helps the young recognize the source of
milk. When a fawn is older and moving about with its mother, the dark
stripe on the white background may serve as a beacon for it to follow.
Habitat
Grant's gazelles are especially fond of open grass plains, and
although they frequent bushy savannas, they avoid areas of high grass.
Behaviour
Grant's gazelles may remain in areas where food is plentiful.
Mature males establish territories they may hold as long as eight
months. A male tries to detain the female herds of 10 to 25 individuals
as they pass through these territories while they move about to feed.
At the same time males chase off rival males and try to mate with
females in estrus.
Grant's gazelles have developed several ritualized postures.
For example, the territorial male stretches and squats in an
exaggerated manner while urinating and dropping dung. This apparently
warns other males to stay away and reduces the number of
confrontations. Younger males will fight, but as they grow older the
ritualized displays often take the place of fights. When fighting does
occur, it also is ritualized. It starts with "pretend" grooming,
repeated scratching of the neck and forehead with a hind foot and
presenting side views of the body. If neither combatant is intimidated,
they may confront one another and clash horns, trying to throw the
other off-balance.
Diet
The gazelles vary their diet according to the season. They eat
herbs, foliage from shrubs, short grasses and shoots. Grant's gazelles
are not restricted to certain habitats by a dependency on water, but
obtain the moisture they need from their food. Grant's have unusually
large salivary glands, possibly an adaptation for secreting fluid to
cope with a relatively dry diet. They typically remain in the open
during the heat of the day, suggesting an efficient system to retain
the necessary fluid in their bodies.
Caring for the Young
Breeding is seasonal, but not firmly fixed. Gestation is
approximately 7 months, and the young are born in areas that provide
some cover. The newborn fawn is carefully cleaned by the mother who
eats the afterbirth. Once the fawn can stand up and has been suckled,
it seeks a suitable hiding place. The mother watches carefully and
evidently memorizes the position before moving away to graze. She
returns to the fawn three to four times during the day to suckle it and
clean the area. The lying-out period is quite long-two weeks or more.
The fawn eats its first solid food at about 1 month, but is
nursed for 6 months. Grant's become sexually mature at about 18 months.
By that time the young males will have joined an all-male bachelor
herd, but it will be some time before they become territory holders, if
at all. Males from the bachelor herds challenge the territorial males,
but only the strongest win territories, which they mark with combined
deposits of dung and urine.
Predators
All the major predators kill Grant's gazelle, but cheetahs and
African hunting dogs are the most prevalent. In some areas jackals prey
on the young. Because of its adaptation to semi-arid and subdesert
ranges as well as its good meat and valuable skin, Grant's gazelle has
been one of the species that scientists consider as a potential source
of protein for humans.