Pit Tag Fact Sheet
animals, one of the biggest technological challenges in wildlife biology,
is easier now at the Savannah River Ecology Laboratory (SREL) with the
recent use of passive integrated transponder (PIT) tags on non-poisonous
snakes, researchers said.
In their mission to conduct long-term monitoring of reptiles and other
wildlife populations on the Savannah River Site, researchers must capture
animals, mark them with some sort of unique identification, release them
and then recapture them periodically. With the use of PIT tags, researchers
are better able to study the individual growth, reproduction, survival
and movement patterns of reptiles and other wildlife.
"PIT tags are one of the biggest breakthroughs in identification
of wildlife," said Dr. Whit Gibbons, a senior research ecologist
at SREL. "Identifying individual snakes especially has been a problem
SREL researchers began using PIT tags on reptiles in October 1991 and
have tagged more than 1,500 non-poisonous snakes to date. The technology
-- at $3 per tag, still very expensive -- has been available since the
mid-1980s and has been used in other U.S. ecology laboratories on fish
and turtles. SREL is among the first laboratories to use PIT tags on snakes.
The tag, about the size of a grain of wild rice, consists of a coded
microchip encased in glass. Researchers inject the tag into a snake's
body cavity through a syringe poked between its lower belly scales. This
procedure causes no known discomfort. When they recapture the snake researchers
use a decoder to read the individual reptile's unique identification number.
"PIT tags have made identification a lot easier," said Tracy
Lynch, a former research technician at SREL. "There is much less
error involved. We don't have to take the time to count a snake's scales
to identify them. Now we can ID a snake in seconds."
Before using PIT tags, SREL researchers identified snakes by counting
a snake's belly scales from its anal opening and clipping the scale edges
at a different numbered location on each snake. This method is not as
accurate as PIT tags because of the possibility for human error, as well
as the deletion of researchers' markings caused by snakes getting injured
or killed by vehicles and/or predators, Ms. Lynch said.
PIT tags, because of their durability, are particularly suited for use
at SREL, where long-term research is made possible by the Savannah River
Site's controlled public access and its designation as a National Environmental
Research Park, Dr. Gibbons said.
Researchers at SREL also will continue to use PIT tags because of the
importance of monitoring the snake population, Dr. Gibbons said.
"Snakes are an important link in ecological food chains," Dr.
Gibbons said. "It's clear from research that diverse biological systems
are interrelated. If you remove one link, it can devastate the system.
Also, snakes are important predators of organisms that carry human diseases,
such as Lyme disease. For example, mice, which some snakes eat, are carriers
during the intermediate stage of the Lyme tick.
"Another reason for studying snake population dynamics and movement
patterns is to give land managers guidance in how forest management practices
affect snake populations. . . . Snake population dynamics provide insight
into subtle environmental changes stemming from land management,"
Dr. Gibbons said.
Researchers at SREL have conducted ongoing reptile studies for more than
25 years. Such a long-term perspective has revealed that snakes thrive
on the SRS because of its large areas of natural habitats, Dr. Gibbons
"The snake populations on the SRS may be at levels perhaps comparable
to what they were well before colonial settlement," Dr. Gibbons said.
"And we hope the snake populations in the surrounding area will someday
attain comparable undisturbed levels because local residents are learning
through SREL's Outreach and Education programs that snakes are not nasty
creatures and shouldn't be killed."