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Radio collars are vital tool for game management |
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January 27, 2016 |
by Roger Phillips
Idaho Fish and Game
Idaho Fish and Game biologist Craig White
recently got a message telling him two elk died,
but it didn't come from a colleague or a
citizen, it was from a satellite. White is Idaho
Fish and Game's Southwest Region Wildlife
Manager, and he got an email telling him two elk
with radio collars stopped moving.
A "mortality" signal was relayed from each
collar to a satellite and beamed back to the
earth, and White was notified.
How had they died? It's an important question
biologists need to know, so White and his crew
loaded trucks, snowmobiles and snowshoes and
headed to the Lowman area between Garden Valley
and Stanley.
Another crew headed by regional wildlife
biologist Michelle Kemner drove and hiked into
the Boise Foothills west of Bogus Basin.
Within 36 hours of getting the email, White and
his crew were performing a necropsy on the elk,
which is an autopsy performed on animals. They
discovered the elk calf was killed by wolves.
Kemner's team had to contact several private
landowners and get permission to cross their
land, but they also arrived within 30 hours and
found a dead calf partially obscured by brush
after a mountain lion tried to conceal it. They
also found two others sets of small tracks, so
they suspect it was a female with two kittens.
The first few days after an animal dies are
critical for biologists to learn the cause of
death and any extenuating circumstances that
might have affected it, such as if it was in a
weakened state from malnutrition, disease or
injury. Did one predator kill it and others
drive it away and feed on the carcass? Or was a
predator even responsible for killing it?
"There are a whole bunch of things we can look
at that are important to know," Kemner said.
"After three or four days, we're losing lots of
that critical evidence."
Within a few days, a wolf pack or black bears
can reduce a carcass to bare bones, and what
they miss scavengers can consume, as well as
scatter the remains. Mountain lions are
notorious for dragging a carcass into rugged,
inaccessible places and stashing them so they
can return later and continue feeding for
several days.
When White joined Fish and Game in 2001,
traditional radio collars were less high-tech,
Back then, he said, biologists and technicians
would drive around several times a month and
track animals via radio signal emitting from the
collars, or fly in aircraft to locate them.
When an animal died, unless the timing was
perfect, it might take days or weeks to discover
it had died and find the carcass. By then, a
necropsy was difficult, not to mention smelly,
and getting good information on what killed the
animal was a challenge.
This time, White's crew was there so quickly
they could see tracks, and even drops of blood
in the snow where a chase occurred. And in an
unexpected coincidence, the same pack of wolves
had killed a cow elk nearby, and that cow had an
ear tag. It had been radio collared in 2009, and
collar dropped off the animal about a year
later, which it was designed to do.
Looking back through Fish and Game's database,
White discovered the cow elk was 14 years old
when it was captured, collared and tagged, which
meant it lived to age 20.
White said it's uncommon to have to have two
mortality signals on the same day, but he
expects more out of the 130 collared elk in
Southwest Idaho because winter is typically when
most die.
Radio collars allow biologists to use signals
and/or satellites to monitor animals across
thousands of square miles. Modern radio collars
blend old and new technologies by sending radio
waves and Global Positions System (GPS) signals
so Fish and Game personnel can track animals and
monitor them from afar, and collars also let
computers do some of the most labor-intensive
and previously costly work.
Fish and Game currently has hundreds of animals
radio collared throughout the state. Collars
give the department the ability to
simultaneously track different animals across
all types of terrain during in any weather
conditions, year round, and track individual
animals for years in some cases. They're an
important tool for ensuring the state has
healthy, sustainable wildlife populations now
and into the future.
Wildlife mortality from malnutrition, predation,
accidents and disease is expected. What is
critically important is the rate at which
animals die, and what causes may restrict a
population from remaining abundant and healthy.
Radio collars make it easier, safer and
cost-effective to identify important pieces of
information.
"It certainly has improved the quantity and
quality of the data," White said.
Deer
In 1998, Fish and Game started intensively using
radio-collared deer as a cornerstone of its mule
deer management program. Fish and Game currently
has about 400 deer with radio collars across 33
hunting units in the state. About half of those
are fawns born last spring. Winter is their most
vulnerable time of year, and fawns are the first
animals in the herd to die during a tough
winter.
Fawn survival typically determines whether a
herd is growing or decreasing. As a rule of
thumb, if at least 45 percent of fawns survive
winter, the herd will grow, and with less it
will decline.
Each winter, crews across Idaho capture deer,
and their goal is to put collars on about 200
fawns and enough does to offset the number of
radio-collared does that died the previous year.
Because fawns are growing so fast, collars are
designed to detach and fall off so they don't
eventually choke the deer.
Knowing how many fawns and does survive winter
helps biologists know whether they can offer
more hunting opportunity, or cut back on the
number of antlerless tags offered for fall
hunts.
Elk
Elk are less prone to winter kill than deer, but
Fish and Game still needs to know how they're
faring throughout winter and whether herds are
growing or decreasing.
That's why last year, Fish and Game started a
similar project with radio-collared elk in six
areas in different parts of the state, including
different habitat types, and different predator
densities. This year, it added two areas, one in
the Frank Church/River of No Return Wilderness
and another in the Diamond Creek area of Eastern
Idaho.
The project includes putting radio collars on 30
adult cow elk and 30 calves in each of the
areas. When the elk are collared, Fish and Game
personnel also check their body condition,
conduct a health and disease assessment and
determine whether cows are pregnant.
"In these first few years, we are keenly
interested in the causes of mortality," said Jon
Rachael, Fish and Game's state wildlife manager.
Knowing how elk die helps biologists understand
what's driving or limiting elk populations in
the different areas of the state.
If animals are in poor condition and a small
percentage of calves are born and survive
through their first year, it could signal
problems with habitat. If elk are healthy and
habitat is good, but herds are shrinking,
predators may be the limiting factor.
If it's predation, information on which
predators are involved is also needed.
While wolves are often thought of as the primary
elk predators, data gathered with the help of
radio collars have shown mountain lions and
bears are also effective elk predators.
Rachael said bears typically prey on newly born
elk calves because the two often inhabit the
same areas during spring, and newborns are a
fairly easy source of protein for hungry bears
coming out of hibernation.
But within a few months, elk calves can elude
bears. Then predation tends to turn toward
wolves and/or mountain lions. Since wolves were
reintroduced, many folks have overlooked the
proportion of elk killed by lions.
In several areas of the state, mountain lions
led wolves in elk predation last year.
Biologists suspect that could change seasonally,
so it may take two or three years to understand
which predators are responsible, and whether
predation is a limiting factor for growing elk
herds.
If wildlife managers learn predators are driving
elk populations below the department's
objectives, and they know which predators are
most responsible, they can adjust hunting
seasons, bag limits, etc. to reduce the predator
population in that area.
Using data from radio collars also allows game
managers to respond quicker to population
changes. In the past, aerial surveys were the
department's best tool for surveying herd sizes
and understanding population trends. Surveys are
still an important tool, but aerial surveys are
only done every three to five years in most
hunting units because of cost limitations.
Monitoring radio-collared animals allows Fish
and Game to monitor populations every year.
"The real strength in using this different type
of data is to improve our ability to predict
deer and elk population sizes between aerial
surveys," Rachael said. "These tools let us do
that much quicker than in the past, which allows
us to be much more responsive to changes."
While surveys can determine what direction
populations are heading, they can't explain why,
so monitoring radio-collared animals is key to
understanding changes.
Wolves
Many wolves have been radio collared since they
were reintroduced into Idaho in 1995. Fish and
Game currently has collars on about 75 wolves,
and crews are in the process of adding about 20
more this month.
Radio collaring wolves provides valuable
information about these nomadic animals that's
important to know for both population estimates
and the knowing where animals gather during key
times of year, such as denning, birthing and
raising pups.
Fish and Game estimates conservatively that
there were about 770 at the end of 2014, and the
counts for 2015 will be tabulated by April.
The animals are spread across most of Idaho from
the Canada border south to the Snake River
Plain. Tracking wolves across that vast area is
extremely difficult without the aid of radio
collars.
The collars help biologists know where to find
wolves, and in some cases, help locate those
responsible for killing livestock; a
rare-but-important use of radio collars to
ensure targeted removal of offending animals.
Radio collaring wolves is time-consuming and
labor intensive, and like other animals, there's
annual wolf mortality, including those wearing
radio collars.
In addition to focused efforts to radio collar
wolves, Fish and Game takes advantage of
incidental encounters with wolves during routine
deer and elk capturing each year to radio collar
enough wolves to offset those that died, or were
killed, the previous year. |
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