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| AP Photo, Courtesy of The Nature Conservancy |
The efficiency of any conservation plan depends on how well it
coincides with the movement of wildlife. And what wildlife movement is more
common than that of migration? Migration is probably the most basic kind of
movement. It’s regular and predictable, season after season. Seasonal
migrations are hard-wired in animals such as deer, elk, and pronghorn. They travel the same paths, to and from the
same regions, year after year. According to The Nature Conservancy(TNC)-Montana Director of Science Brian Martin, “They’re willing to push
through pretty crummy conditions to get to these well-known destinations.”
However, wildlife can reach its breaking point if we put up enough barriers
between them and their migration grounds. If that happens, the migration flow
will stop abruptly and have serious side effects like the loss of genetic
diversity in the population. In order to prevent this, the best option is to
identify established migration routes and try to protect them (Wildlife in
Motion).
Another important aspect to remember is connectivity. In simple
terms, connectivity enables wildlife to move across lands to the places they
need for food, shelter, mating, and nurturing their young. What isn’t simple is
the task of maintaining connectivity through wildlife and migration corridors
(Wildlife in Motion). In Montana, TNC is currently working on a project
“documenting barriers conventional fences pose to wildlife [in an attempt] to
spur modifications that are more ‘wildlife friendly’” (Puckett). The focus
animal for this project is the pronghorn that “have roamed the continent for
millennia. They were contemporaries of the long-extinct Wooly Mammoth and
Saber-toothed cat.” Scientists theorize that the major trait that allowed them
to survive was their undeniable speed. A pronghorn’s “ability to run up to 60
miles an hour makes [them] second only to cheetahs as the planet’s fastest land
animals.” It’s because of their speed that they've earned nicknames such as “speed
goat” and “sagebrush rocket;” however, they are more commonly referred to as
“antelope” (Built for Speed).
An interesting fact not many people know is that “taxonomically,
the pronghorn is the only animal left in its family,” according to Andrew
Jakes, wildlife researcher and Ph.D. candidate at the University of Calgary.
Actually, the “pronghorn’s closest relatives, genetically, are giraffes, not
deer, elk, and moose” (Built for Speed).
In addition to the pronghorn’s speed, its ability to travel great
distances has served it well since herds migrate hundreds of miles to reach
their seasonal grazing grounds. Based on data from his current project, Jakes
and his colleagues have discovered that the “longest pronghorn migrations in
the world-300-500 miles annually, occur in the Northern Great Plains of
Alberta, Saskatchewan and Montana.” And with no current predators, the
pronghorn’s greatest threat is human development in the form of “roads,
irrigation canals, and hundreds of thousands of miles of fences, which are
serious obstacles that pronghorn won’t jump over the way deer and elk will”
(Built for Speed).
Many wonder why pronghorn don’t just jump over the fences; well,
Jakes says jumping is a learned trait that they’ve never needed before. The
terrain the pronghorn call home doesn’t necessitate the need to jump over
anything larger than sagebrush (Built for Speed). As a result, the pronghorn
crawl underneath the fences instead of jumping over them but in doing so they “often
catch their backs on the barbs when they wiggle through. The repeated
scratching causes scarring and wears away the fur, which Martin says makes the
animals more susceptible to cold weather” (Puckett).
So, how can we help?
Andrew Jakes and TNC have come up with a plan of action in which
small changes to the fencing can make a world of difference to the pronghorn
and help make their migration much smoother. It’s completely out of the
question to replace all the fencing in Montana, but “switching out or modifying
fences so that pronghorn can crawl under” without injury and “leaving certain
gates open during times of migration” are better options. Doing this will make
pronghorn migration easier because they “naturally follow particular migration
corridors and learn where there are breaks in barriers like fences,” knowledge the
pronghorn will pass on to their young (Built for Speed).
The guidelines for wildlife friendly fences include making the
fences not too tall for animals to jump over, allowing more space between wires
so animals don’t get entangled, and making the bottom wire tall enough that
animals can successfully crawl under. In more specific terms, “wire fences
should be no higher than 40” with 12” between the top two wires and 18”
clearance between the bottom strand and the ground. Ideally, the bottom wire
should be smooth rather than barbed.” Simply removing the bottom wire and
replacing it with a smooth one is an easy way to modify old fences along the
migration route. Some fences can even include a gate to be opened during
migration season (Built for Speed).
Another aspect of the project includes installing remote cameras
placed at fence “modification points to record how animals are using them”
(Built for Speed). The cameras are motion activated from up to 21 feet away
every second. Even before modifications were made, some fences already had
cameras set up to record pronghorn movements, some of which “show antelope
standing at the fence[s] or walking along them. Data from Jakes’ pronghorn
migration study, which involved tracking animals with GPS collars, showed that
antelope sometimes spent a week or longer walking back and forth along fence
lines” which uses up valuable energy. “They’re burning a lot of calories, which
may not directly kill them but makes their chance for mortality much higher,” Martin
said. These pictures show a clear need for wildlife friendly fencing along the
migration routes which run north-south so the focus is on fencing that runs
east-west (Puckett).
The important thing to remember is that animals were here first
and as we encroach on their habitats and make their movements to migration
regions more difficult there are small changes we can make to give them an
easier and safer commute.
References:
Built for Speed: Pronghorn Migration, The Nature
Conservancy-Montana, Alison James and Bebe Crouse
Group documents wildlife barriers: The Nature Conservancy aims to make fences ‘wildlife friendly,’ Karl Puckett of The Great Falls Tribune
Wildlife in Motion, The Nature Conservancy-Montana
