Biology Reference
In-Depth Information
trusion has been supposed to have magical properties: it has been prized as medicine to
quell life-threatening fevers, rumored in Vietnam to cure cancer, and nearly everywhere er-
roneously believed to elevate libido. In 2012, rhino horn was worth more than its weight in
gold, and its value skyrocketed to $100,000 a kilogram. For this object, rhinos have been a
favorite target of poachers, even though, as one wag put it, ingesting rhino horn has the same
medicinal value as gnawing one's fingernails, also made of keratin.
None of the claims hold up to scientific scrutiny, but myths linger. A most stubborn belief
surrounds the value of rhino urine, known as
muth
. Drinking the foul liquid, which fetches
five dollars a liter on the open market, supposedly cures asthma and tuberculosis, while ap-
plying a few drops is said to heal inner ear infections. My elephant driver, Gyan Bahadur,
and his colleagues routinely jumped off their mounts to gather up the spilled urine in a plastic
bag when a rhino happened to urinate in front of them.
We've now moved from the cool jack pine forests of the northern United States to the
steamy lowland jungles at the base of the Himalayas to investigate several new causes of
rarity. The 14-gram Kirtland's warbler was rare because of limited breeding habitat and nest-
ing disruption by cowbirds. But this bird can potentially nest anywhere across the jack pine
belt of the northern continental United States where the trees are young and the soil is sandy.
The 2,000-kilogram one-horned rhinoceros, in contrast, is much more range limited, rarely
wandering farther than two kilometers from water and feeding intensively on the thin strip of
wild sugarcane that borders the major rivers of lowland Nepal and northern India. The Kirt-
land's, like many other rarities, evolved as a fire-dependent species. The greater one-horned
rhino and some other narrowrange species evolved as floodplain specialists—those that per-
sist only close to the river's edge.
Another difference between the two habitat specialists is the level of competition with hu-
mans: agriculturalists covet the siltrich grasslands found along the riverbanks and have trans-
formed them into the rice bowl of South Asia. In contrast, the nutrientpoor, rapidly percolat-
ing soils in the jack pine zone deter farmers from the thought of grain production. The two
species lie at opposite ends of the demographic spectrum as well. A female Kirtland's typ-
ically dies by four years of age or younger, whereas a female rhino can live as long as fifty
years.
The greatest differences and most important new causes of rarity to explore are human
predation and breeding biology. As rare as Kirtland's warblers are, no Native American tribe
ever coveted their feathers for headdresses as we saw New Guinea highlanders use bird
of paradise feathers or Amerindians in Peru hunt macaws for the same purpose. Michigan
homesteaders never used Kirtland's warbler meat, beaks, or claws as cures or aphrodisiacs.
Poaching was simply never an issue, in contrast with what all rhinos face from Africa to
Asia. And as we shall see, the critical demographic feature that dictates recovery or doom
for a rhino population depends upon females living to a ripe age and producing as many
