November 2013 - Parks & Recreation - 49

Beavers
Who doesn't love these large, endearing, semi-aquatic rodents with giant
teeth? Beavers build intricate marvels
of natural engineering and create
acres of valuable new habitat for wildlife. What's not to like about them?
Plenty, if you ask highway engineers,
landscape designers, golf course superintendents and park managers.
Beavers are remarkable animals.
They feed exclusively on plants, usually the inner bark of softwood tree
species that they cut down, and store
caches underwater for their winter
food supply. They also build dams
on the headwaters of streams for one
primary purpose - to submerge the
underwater entrance to their lodges.
Beavers were once widespread
through North America, but trapping
nearly extirpated this species from
its entire range. They have made a
significant comeback in most areas
of their historic range in the last 50
years, sometimes to the point of
overpopulation, causing no amount

of consternation to park managers
and public works employees.
Beavers are one wildlife species in
which creative management solutions
can sometimes work. When biologists
observed that the primary stimulus that
caused beavers to build dams was the
sound of running water, they devised
ingenious pond levelers and water-control structures that allow water to drain
almost silently in normal flow conditions. The beavers no longer hear running water, and as a result, they cease or
slow construction of their dams.
When beavers have filled their
available habitat, they will resort to
living in areas undesirable to man,
such as highway drainage culverts,
roadway crossings or golf courses.
Live trapping and relocating beavers is usually not a viable solution
for control for a number of reasons,
including state and local laws prohibiting transportation of these and other
furbearers.
Canada Geese
" Resident " Canada geese, as distinguished from migratory Canada
geese, have only become a nuisance
wildlife problem in recent decades.
Once a beloved wildlife species,
Canada geese numbers were greatly
reduced by overly permissive hunting laws and other factors, and the

populations in the major flyways
were reduced to much smaller wintering flocks. Dale Humburg, chief
scientist for Ducks Unlimited, says,
" Efforts to restore historic populations of Canada geese began in the
'60s and '70s. Giant Canada geese
had almost become extinct as a
subspecies. "
State natural resources agencies
actively tried to reintroduce them
within their historic wintering range
by trapping and translocating them
to parks, agricultural ponds, rivers
and lakes. Here, geese benefited
from the lack of predators, abundant local food supply and congenial climes. They bred very successfully, and then, not having the
ancestral knowledge of how to fly
home, no longer migrated back to
Canada each spring. They are now
year-round species throughout every flyway. " Wherever they wound

up, especially in a park, people really enjoyed them, " Humburg says.
" They had no idea of the potential
problem that would develop. "
Today, there are about 4 million
resident Canada geese in the U.S.,
grown from a population of about
250,000 in the 1970s. Resident geese

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Parks & Recreation

City of Atlanta Department of Parks and Recreation (beaver), Lee Aurich (geese)

ager for Columbus and Franklin County Metro Parks in central Ohio, says,
" Some of our parks had concentrations of 400 to 450 per square mile. "
Deer biologists say that concentrations of deer at 40 to 50 per square
mile can be considered overpopulated and can cause damage to natural
ecosystems. Watts described the development of a management program
that first started with gathering data,
engaging the public, and employing a
variety of control methods including
deer contraceptives, culling, managed
public hunts and continuous public
education. He says, " After our years
of experience, it is clear that there is
no one answer that solves all problems
or applies to every situation. We found
that we needed to keep all options on
the table, and that seems to work. "

November 2013 - Parks & Recreation

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