DO ECOLOGISTS SAMPLE HARMLESSLY?
by Whit Gibbons
September 2, 2002
Amid the clamor about protecting the world's wildlife, efforts by
some ecologists to preserve animals go unnoticed by many. I am not
referring to strategies employed by environmentalists but to those
of researchers exploring biological mysteries while trying to preserve
the research specimen. That is, how do you explore certain aspects
of an animal's biology without killing the animal?
Killing animals for research was once considered routine and essential
to answer certain questions. Numerous scientific publications refer
to the dissection of hundreds of turtles to find out what they were
eating or how many eggs they were going to lay. Thousands of mammals,
birds, reptiles, and amphibians have been killed to determine how
much fat they stored, what their reproductive condition was, or what
kind of parasites they had.
Finding out the answers to such questions is not a trivial pursuit.
Such information is essential to understanding the structure and organization
of different species, as well as their role and importance in an ecosystem.
But many species can no longer tolerate unlimited destruction. The
dissection of a fifty-year-old alligator snapping turtle results in
the removal of an important member of a habitat--one that has required
half a century to produce. Ecologists now have a variety of techniques
that produce answers while leaving the animal intact.
One approach is x-ray photography, a tool in human medicine for decades.
Today, x-rays reveal phenomena about animals other than humans, particularly
reptiles that lay eggs. This includes all crocodilians and turtles
as well as most snakes and lizards. Knowing the reproductive characteristics
of a species is essential to understanding its biology. X-ray photography
enables ecologists to gather pertinent data about the number and size
of eggs, and then return the animal unharmed to its original habitat.
A more recent advancement is the use of ultrasound technology to count
eggs or embryos in wild animals without harming them.
These nondestructive sampling methods are important to many ecological
studies. The advantage in the study of rare or endangered species,
when the loss of a single specimen is undesirable, is particularly
clear. For example, research in New Zealand on the internationally
endangered tuatara, which looks like a large lizard, relied on x-ray
photography. Thus reproductive information was obtained, but none
of the tuataras were dissected or harmed in any way. The findings
were critical for understanding population growth patterns in these
unusual animals that are on the verge of extinction.
The dietary habits of wild animals are also an important ecological
characteristic for determining how each adapts to and affects its
environment. Such information is necessary for proper wildlife management
of some species or to understand the position of a species in the
food web of a community. One approach used with some reptiles, mainly
turtles, is the stomach pump. No ecologist would go so far as to say
a turtle likes to have its latest meal flushed out of its stomach,
but the approach beats the old-fashioned alternative--dissection.
Dietary preferences have been determined for many individual turtles
that continue to live happily in their native habitats.
Nondestructive sampling in research ecology is now common for many
species of animals, particularly those that are rare, endangered,
or that naturally live for many years. For example, few turtles of
any species are killed for dissection by ecologists anywhere in the
world today because of the advent of these techniques and others.
The field of ecology, not to mention many species of animals themselves,
has benefited greatly from the development and use of nondestructive
However, this is not an indictment of researchers who have killed
animals in the past or those who kill animals today under certain
circumstances. Although research ecologists should proceed in the
spirit of modern-day efforts to preserve natural populations, they
sometimes have to dissect specimens or place them in permanent museum
collections for future study. If such decisions are made judiciously,
with an awareness of the impact on the total environment, destructive
sampling can make useful contributions to science and society. Today's
ecologists are getting better and better at making such decisions.
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