Page 50 - BBC Wildlife Volume 36 #04

GHARIALS

SUPER

SNOZZLE

elop
Mature male gharials develop a
large lump called the gharra (Hindi
for ‘earthen pot’) at the end of their
n
s
snouts. This cartilaginous structure,
k
covering the nostrils, makes the
males visibly different from females.
Often, it is distinctive enough to tell
individual males apart. Its internal
architecture includes many folds.
When a male demonstrates his
machismo, he squeezes air through
these nasal passages, adding a buzz
to his snorting. Without opening
their jaws, male gharials also make
a popping sound underwater,
audible to their rivals within 500m.
Experts speculate that the ghara
may act as a resonator, advertising
an animal’s identity and location.

days, until he finally realises that he cannot unseat the use rivers. It is supported by international zoos through
winner and gives up. theMadras Crocodile Bank Trust, an Indian reptileand
Female gharials watch the outcome of the titanic battle amphibian conservation organisation, and over the past
with keen interest, because the victorious male will father decade has attached radioandGPS transmitters to more
their offspring. But Jeffrey Lang, a retired professor of than 50 gharials and installed trail cameras at nesting sites
biology from the University of North Dakota, saysit’snot to study their behaviour. Lang’s main finding: these animals
so simple. Some females may not settle for just one mate, are unlike any other crocodilian in the world.
instead travelling along the river to visit other dominant As spring lifts the low-lying mist from the Chambal,
males. In 2008 Lang founded the Gharial Ecology Project flocks of winter migrants – bar-headed geese and Brahminy
after a mysterious die-off the previous winter, when more ducks – take to the skies heading for their summer homes.
than 100 gharials were found floating lifeless in the And egg-heavy female gharials labour up steep sandbanks
ChambalRiver. to dig nests under the cover of darkness. Their stubby
legs barely support their weight. Females of most other
UNCERTAIN FUTURE crocodilian species put distance between each other. But
When vets cut through thecadavers, they saw uric acid gharials do it differently. Each nest is no more than a gharial
crystals caked on the internal organs and solidified in body-length or two away, and as many as 20 or 30 females
the joints. Gout. Their kidneys had failed. Some toxin may share a sandbank, often the same one year after year.
had killed gharials of a particular size: 2–4m in length. Lang has observed the females don’t make nests at the
Mugger crocodiles, turtles, Ganges river dolphins, fish very top of a sandbank but about two-thirds of the way
and waterbirds escaped its clutches. It didn’t even affect up. This strategy makes it difficult for predators such as
small gharials or the big adults. In 2006, experts had jackalsandhyenas to reach them. Gharial eggs, as big as
declared that only 200 adultgharials survived in India geese eggs, are the largest of any crocodilians. An average
and Nepal, so the catastrophe had severe implications for clutch has between 35 and 50 – a feast for any egg thief
the species’ future. that manages to dig its way into a nest. But the predator
Despite being a tributary of the holy but polluted has to bolt as many as it can, for the mother gharials aren’t
Ganges, the Chambal is a relatively clean river. How far away. They lie soaking in the deep waters below the
were the gharials poisoned then? Suspicion pointed to sandbank, keeping an eye out for prying claws.
the Yamuna River, which drains industrial effluents and Although they have sharp teeth and could seriously injure
sewerage from cities like Delhi and Agra. Did gharials their enemies, gharials do not eat them. Their teeth have
of the Chambal swim 50–60km downriver to the septic custom-evolved to grab slipperyfish. Despite their enormous
Yamuna? No one knew. size, these reptiles have no gastronomic interest in birds or
By setting up the Gharial Ecology Project, Lang hoped to mammals (including humans), alive or dead. No other big
gha
how
find out. One of its key aims is to understand how gharials crocodilian eschews mammalian flesh to this degree.
50 BBC Wildlife