|
| Tracks |
September 14th, 2003.
By Professor Fabio Cupul
Permanent Member of SOMEDICYT, the prestigious Mexican
Society for the Dissemination of Science and Techniques.
VERSION
EN ESPAÑOL |
During the Sixties, American zoologist
Marlin Perkins, famous for his “Wild Kingdom”
TV program, demonstrated that the impressive gigantic
humanoid tracks in the snowy lands of the Himalayas,
contrary to popular belief, were not left by the legendary
mythical Yeti (from “yeh-teh” in the Sherpa
language, meaning “that from over there”);
but rather they were fox tracks distorted when the ice
around them melted with the heat of the sun.
The preceding can give us an idea
of the imprecision that can arise in determining the
identity of a living being based on an erroneous identification
of its tracks. It is quite probable that animal tracks
do not provide any information for our reader who is
a member of an urbanized society. Nevertheless, for
some groups of contemporary humans in close contact
with nature, as it was with our ancestors, knowledge
of animal signs make the difference between getting
one’s daily food or spending another day with
an empty stomach.
Most animals are shy, meaning that
they are hard to observe. Thus their signs, which include
their tracks, provide important information about their
behavior and life history. Within those signs, that
could be defined as trails, traces, signs or indications
that living beings leave behind during their activities,
besides any sign, relics or vestiges that survive them,
there are also tracks, foot or paw prints, paths, burrows,
dens and lairs, excretions, food remnants, voices, sounds
or odors, among others.
The study of animal signs and tracks
is really detective work. It requires their meticulous
assessment in order to establish the subtleties that
differentiate them from one another (by species, sex
or age) and the behavior of the animal at the moment
when he left them in the mud, the sand, the dust or
the snow. In other words, to quote biologist Marcelo
Aranda, “tracking is a valuable method to learn
about animal habits as it is practically the same as
observing an animal for a long period of time under
natural conditions; tracks, traces or trails are a language
of signs that requires sure interpretation in order
to be understood.”
The study of tracks on the surface
of the earth is not limited to those left by living
beings presently inhabiting the planet, much research
has been done on the signs left by animals who lived
in the past, including man. They speak to us about their
evolution and way of life. With regard to the evolution
to today’s man’s biped walking (upright,
on two feet), there is evidence of the beginning of
this process in a series of fossilized footprints found
in Laetoli, Tanzania, that demonstrate that the beginning
of our ancestors’ biped locomotion occurred at
least 3.6 million years ago.
Although the fossilized remains of
dinosaurs are quite common, their footprints -called
fossil tracks (also known as icnites), only appear occasionally.
The tracks left by dinosaurs on fine clay would harden
under the sun and sometimes fossilize. Careful study
of those fossil tracks can reveal useful information
on how those dinosaurs walked, ran and hunted.
But animal paw prints are not
the only things that help our understanding of their
natural history. For native American Indians, the observation
of signs that proved the presence of wolves was an unequivocal
sign of good luck as they meant that deer or bison herds
were nearby. To thank them for helping them find prey
with which to feed themselves, the natives did not kill
a prey without first offering a piece of it to the wolves.
Vallarta's Nature Field Guide - File 7
The Booby Birds
 The
name booby derived from the bird’s limited experience
with human presence within its isolated islands, a fact
that caused its curiosity to surpass the alarm caused
by the famished sailors lying in wait. Due to their
innocence, and because they did not defend themselves
or fly away when pursued, sailors would hit them over
the head to kill them and eat them immediately or to
put them into the “booby depository”, a
small container below the deck of the boat that supplied
fresh meat, and which was continuously replenished.
But we shouldn’t assume that these are stupid
birds. This is a species that evolved in island environments
free of predators, reducing the need -within their instincts-
to remain alert to the occurrence of a potential hunter.
Within our Bay of Banderas, there are four species of
boobies, pelagic marine birds (i.e.: that live on the
open sea) measuring between 70 and 100 centimeters in
length. Their plumage is white, brown and black in contrast
with the bright colors of their face and feet. Among
those species, the most common are the blue-footed booby
(Sula nebouxii) and the brown booby (Sula leucogaster).
The former is larger than any seagull, mainly brownish-gray,
the head, throat and breast are usually spotted with
white, the lower part of the breast and abdomen is white,
the naked skin on the throat is slate-colored, the big
feet are blue and the tail is pointed. The latter’s
plumage is dark brown, nearly black, with white stomach
and sides in marked contrast with the dark breast, the
beak is yellowish to light blue, the feet are yellow,
the naked skin of the face and throat is also yellowish
to blue. Only the blue-footed booby is classified as
being in danger of extinction.
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