Dale Matson
Click On Photographs To Enlarge
I was backpacking near Reflection Lake and took a photograph
of a deer with two tracking collars. Why would there be a need for two collars?
From: "Gammons, Daniel"
<daniel_gammons@nps.gov>
Date: Friday, September 5, 2014 at 11:29 AM
To: Dale Matson <dematson@comcast.net>
Cc: NPS SEKI Interpretation
<seki_interpretation@nps.gov>
Subject: Fwd: From NPS.gov: Deer with two tracking collars
Mr. Matson,
Each radio collar serves a different purpose--one is a GPS
(Global Positioning System) collar and the other is a VHF (Very High Frequency)
collar. The GPS collars collect spatial
data through the satellite system, which is used to study space use and
migration patterns. These collars have a
relatively short lifespan, lasting only a year or two. The VHF collars have the advantage of a much
longer battery life, lasting several years, but they do not collect any data
themselves. Their primary purpose is to
indicate to a remote observer, who can listen to the signal produced by the
collar with a receiver (similar to listening to the radio) whether the deer
remains alive or not. The VHF collars
have a tip-switch in them with a ball-bearing that rolls back and forth. If that ball-bearing stops moving, the signal
transmitted by the collar changes, indicating that the collar is no longer
moving. Researchers can then locate the
collar to determine whether it simply came off the animal or if the animal is
dead.
These deer were originally radio-collared by the California
Department of Fish and Wildlife in the Owens Valley, but their annual migration
brings them upslope into Sequoia and Kings Canyon National Parks.
Sincerely,
Daniel Gammons
Wildlife Biologist
Sequoia and Kings Canyon National Parks
47050 Generals Highway
Three Rivers, CA 93271
(559) 565-3124
daniel_gammons@nps.gov
Daniel,
I appreciate the prompt reply and the rationale for the two
collars. It seems to me that if the deer migrate that far, the VHF would no
longer reach the remote observer. Additionally, I would suggest (and hope the
technology is available) that when the GPS collar is no longer functional that
the collars could have an 'on board' mechanism to release the collar from the
neck of the deer. I am not a member of an animal rights group but believe
scientific investigation should be as humane as possible. I have attached a
photograph of the deer.
Thanks,
Dale Matson
Mr. Matson,
You are correct in that there is a
limited distance at which VHF signals can be detected remotely. This is overcome by listening for signals
from aircraft. At several thousand feet
in elevation above the signal, it can be detected from many miles away. The GPS collars are programmed to be
automatically released after 1 year of data collection or just before the
battery dies, whichever comes first.
Thanks very much for the
photograph. Out of about 100 deer that
were radio-collared last spring, only 5 received both VHF and GPS collars. In a way, you were lucky to see one. The reason only a small number received GPS
collars is because since deer travel in social groups, fine scale location data
will be quite similar between animals, while survival rates will vary (which is
why all of them have VHF collars).
Sincerely,
Daniel Gammons
Wildlife Biologist
Sequoia and Kings Canyon National
Parks
47050 Generals Highway
Three Rivers, CA 93271
(559) 565-3124
daniel_gammons@nps.gov
Daniel,
Thanks again for your response. Your information has made me
more understanding and sympathetic to the process. As someone who conducted
research with humans, I needed informed consent and realize the importance of
humane treatment of the subject in data gathering. Thanks for the work that you
do.
Pax,
Dale Matson
Note: I appreciate the quick response I received from Daniel Gammons and his respectful willingness to explain in detail the rationale for the two collars even though it was the CDFW that installed the collars on the deer.
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