Biology Reference
In-Depth Information
In the meantime, George has looked at the tracking data for the male jaguars to see whether
they follow the same patterns. It turns out that males tend to wander more widely over the
floodplain than do the females, perhaps moving from female to female in search of breeding
opportunities as large cats are typically known to do. George speculated that the big males, al-
most twice the size of females, can more easily bring down the tusk-laden peccaries—which
themselves are nearly the size of female jaguars—with less dependence on the element of
surprise. This may support the view that females prowl the riverbanks because the dense un-
derstory gives them more cover from which to launch an attack. If the males, on the other
hand, depend less on short-range surprise attacks, they can focus on their second most im-
portant drive, cherchez la femme.
For assembling a picture of jaguar movements, a missing piece was knowledge of the dens-
ity of jaguars far from river channels, where peccaries are few. To address this, George and
his team needed a research site in the upland forest. He found a well-managed timbering op-
eration where hunting was prohibited and obtained the local landowner's permission to use
the concession as home base, allowing the team access to the vast uplands. Although this
study is still under way, initial data indicate the big cats use larger home ranges in the upland
areas, perhaps because of the near absence of their preferred prey, the white-lipped peccary.
“My data clearly show that white-lipped peccaries are super common in the floodplain hab-
itats, but rare in the upland forest away from the flooding,” George wrote in his journal. “I
will be curious to see if plant sampling data show that the extensive upland forest is largely
devoid of the large palms whose nuts the white-lippeds depend on. At least that is what we
expect.”
George's inquiry into how jaguars and pumas share the range, or avoid each other entirely,
was only partially answered. His preliminary data indicate that pumas seem to be similar to
jaguars in their preference for riverine habitats but with the caveat that there is little or no
overlap between male territories. Unfortunately, female pumas turned out to be too small to
carry a TrackTag collar. (Typically, researchers try to keep telemetry devices within 5 per-
cent of an animal's body mass, to avoid interfering with its behavior.) Thus, greater insight
into how these two cats fit together in ecological space awaits yet another advance in the
technology of animal tracking.
One can infer only so much about the causes of rarity by mapping jaguar or puma dis-
tributions. Perhaps greater understanding comes from looking across the ocean at another
pair of large feline predators: tigers and leopards in South Asia. A common saying among
old jungle-wallahs there is that “where tigers are common, leopards are scarce.” Tigers are
known to kill leopards, and in areas of high tiger density, leopards stay close to the margins
of wildlands and closer to human settlements, where tigers tread less frequently. Perhaps pu-
mas, especially the smaller females, are strongly influenced by the movements and ranging
of jaguars and stay in areas avoided by jaguars.
