clipped from the U. S. Geological Survey general announcements:
 
Advances in telemetry benefit wildlife researchers
 
Monitoring: Technological advances enable researchers to track species more
accurately.  By Ori Nir Special to the Mercury News
 
David Mech of the U.S. Geological Survey's Minnesota office can document
the changes. In 1983 he published the Handbook of Radio Tracking and has
been involved in the science of telemetry for 40years.
 
Jerry Godbey, a biologist with the USGS in Fort Collins, Colo., uses
transmitters in collars weighing a quarter of an ounce to monitor
black-footed ferrets, a critically endangered prairie species and one of
the rarest mammals in North America.
 
These weasel-like creatures became so rare 20 years ago that scientists
thought they were extinct.  Now, experts are keeping a watchful eye to
protect the small population they managed to save.
 
Monitoring ferrets is not easy because they spend much of their life in
burrows and are nocturnal.  ``The transmitters allow us to tell when the
ferrets come up and when they go underground.  They tell us when they move
and when they are still,'' Godbey said.
 
Godbey uses a rather conventional method of receiving data from the
collared ferrets.  A very high frequency radio transmitter in the collar
sends out a steady beep, which is intercepted by receivers in three
trailers with large antennas.
 
Staffed by students in two shifts from dusk to dawn, the trailers are in
sites that make it easy to pinpoint the animal's precise location.  This
method, known as triangulation -- determining a specific location by
marking it on three axes -- is key to radio telemetry.
 
Once consecutive location points are determined, scientists can track the
animal's movement by connecting location dots.  Godbey records the ferret's
location every 10 minutes.  When the animal is underground, the signal is
gone.  When it's still, the signal's sound changes.
 
The transmitter is harnessed to the animal by a biodegradable woolen
collar, which drops off when the wool disintegrates after the transmitter's
battery runs out.  The scientist obtains the data, and the animal -- hardly
affected by the transmitter when it's in operation --doesn't have to carry
it around after it ceases to operate.
[Posted in FML issue 2925]