Biology Reference
In-Depth Information
spontaneum
), or wild sugarcane, is what rhinos really prefer. The wild cane remains green for
much of the year and sprouts anew in response to grazing, cutting, fire, or inundation. Year-
round, kans accounts for at least half the monthly diet of the rhino; of all the rhinos' potential
forage grasses, kans turned out to have the most protein and to be one of the most digestible.
So rhinos are not only grassland specialists but also kans connoisseurs. Using their prehensile
upper lips to wrap around the stems and their high-crowned molars to chew them up, rhinos
are highly proficient mowing machines.
The kans grasslands and some of the other short grasslands adjacent to them or mixed in
with them were also the preferred feeding areas for the tiger's prey. The density of deer and
wild boars in the kans and riverine forests was among the highest recorded wherever this hab-
itat occurs in Nepal and India.
Floodplains in Asia are among the most productive landscapes on Earth for rhinos, tigers,
and other animals as well. Such rich, fertile soil supports, for example, the endangered swamp
deer, extinct in Chitwan since 1950 but still present in small numbers in Bardia and abundant
in the Suklaphanta reserve. Rare across much of its range in Nepal and India, the deer forms
herds that number in the hundreds, until recently in the thousands, in open grasslands in Suk-
laphanta. The same is true for the endangered hog deer, which is rare elsewhere but quite
common in the kans, sometimes traveling in herds of thirty or more. And wild water buffalo,
which used to be common in Chitwan but now have been extirpated, were reportedly found
only in the riverine grasslands. The foraging patterns of all these large-bodied species illus-
trate how the highly productive kans, the first elephant grass in the line of succession along
riverbanks, is the keystone plant species offering the most critical habitat in this large-mam-
mal ecosystem.
Another critical habitat element for rhinos is water. During the hot, steamy monsoon, rhi-
nos are unable to sweat fast enough to cool off; to compensate, they become almost semi-
aquatic, spending up to eight hours a day submerged up to their nostrils. When they wallow
on their side, their broad bodies form perfect sundecks for rows of amphibians. When the rhi-
nos turn over, the frogs quickly shift to their new perch.
Rhinos concentrate close to rivers, near the ribbon of wild cane, and in areas pockmarked
by wallows. Chitwan offers all of these features. With rhinoceroses so locally abundant there,
I had to keep reminding myself just how globally rare these creatures truly are. On a typical
hot spring morning in 1987 in the Pipariya grassland, for example, rhinos, especially mothers
and calves, seemed to be everywhere. Within the span of two hours, in an area no bigger than
a shopping-mall parking lot, we counted thirty-five individuals, the highest concentration I
had ever seen. A morning stroll across the grassland would demonstrate the truth of local
abundance to any ecologist who doubted that such a thing was possible, even for a rhino.
