Beavers are well established and moving through the Oregon Coast Range


Date:
August 30, 2021
Source:
Oregon State University
Summary:
Beavers are often translocated to restore populations in areas,
reduce their conflicts with humans and to take advantage of their
ability to improve ecosystems. However, few studies have accessed
the impacts of dispersing beavers, making it difficult to determine
best practices for translocations.



FULL STORY ========================================================================== Beavers are often translocated to restore populations in areas, reduce
their conflicts with humans and to take advantage of their ability to
improve ecosystems.


========================================================================== However, few studies have accessed the impacts of dispersing beavers,
making it difficult to determine best practices for translocations. A new
study from scientists at Oregon State University and the U.S. Department
of Agriculture's National Wildlife Research Center begins to change that.

The scientists, who collected genetic samples from almost 300 beavers in
the Coast Range of western Oregon, sought to understand whether landscape features, such as slope and distance to water, influenced gene flow
among beavers.

They detected relatively strong genetic differentiation of beavers, which
they believe is shaped by watershed boundaries and past relocations of
the rodents.

This led them to recommend that relocation efforts of beavers in topographically complex landscapes, like the Coast Range, occur within watersheds when possible.

"We wanted to see if there were things that are limiting beaver
dispersal in western Oregon, whether they are not able to disperse
because of geography or some physical limits," said Jimmy Taylor,
a research wildlife biologist with the U.S.D.A's National Wildlife
Research Center in Corvallis and a courtesy faculty member at Oregon
State. "Our findings indicate that doesn't seem to be the case. They
seem to be moving freely within watersheds, with at least occasional
movements between watersheds." The overharvest of beavers during the
16th to 19th centuries in North America is well documented. This legacy, however, sometimes overshadows the restoration of beaver populations
throughout North America in the 20thcentury.



========================================================================== Spurred by the population restoration, there has been growing interest
in the western United States in using beavers for stream restoration
projects that can restore floodplain connectivity, improve grazing opportunities for livestock, mitigate increasing aridity and provide
habitat for threatened species, such as Oregon Coast coho salmon.

In the recently published paper, the researchers focused on beavers in
the Coast Range of Oregon, a region characterized by multiple watersheds,
dense forests and steep hillside slopes.

The team reviewed the limited scientific literature and historical
documents about beavers in the region and concluded not much is known
about beaver history or ecology in the area. They did, however, find
records showing more than 700 beavers were released in the area between
1939 and 1951 by the state to provide optimal distribution of the species.

"Beavers are a really storied part of this landscape and they are an
iconic species for Oregon," said Clint Epps, a wildlife biologist at
Oregon State and co-author of the paper. "For me, it was kind of a mystery
of how beavers have persisted in this Coast Range landscape. How much of
that was influenced by translocation? How much of it was just beavers persisting on their own? I can't say we directly tested this. But from
looking at the translocation records and the genetic structure it looks
to me like they hung on in this landscape." The researchers collected
genetic samples from 292 beavers from 12 counties along the Oregon
Coast. They live-trapped 232. The remainder were either road kill or
supplied by trappers.



==========================================================================
They then mapped records of beaver translocations during the 20th century
to consider the effect of those movements on the genetic structure
of beavers.

They concluded that slope and distance to water did not strongly limit dispersal and gene flow by beavers in this system, but that dispersal
is more common within watersheds, as opposed to between watersheds.

"This is a native species" Taylor said. "I'm pleased we see gene
flow. This is an animal that's well established and dispersing in its
native ecosystem." Taylor is also hopeful that this research will lead
to a greater appreciation of beavers in the Coast Range, where they
are not as visible because they don't tend to build dams or lodges in
that landscape.

"There are a lot of beavers on the landscape but people don't know that
because they don't see the classic signs that they learned in children's books," he said. "Part of what I'm trying to do is politely, respectfully educate people that there are a lot more on the landscape out there,
and they are not all providing the cascading series of dams that people
are looking for, but they still contribute to ecosystem services."
Other authors of the paper are Vanessa Petro, a senior faculty research assistant in Oregon State's College of Forestry, who did most of the
trapping; Rachel Crowhurst, a senior faculty research assistant in Oregon State's College of Agricultural Sciences, who did the genetic analysis;
Tyler Creech, who worked with Epps at Oregon State and is now at the
Center for Large Landscape Conservation in Bozeman, Montana; and Matthew
Weldy, a Ph.D. student in the Department of Forestry, Ecosystems, and
Society at Oregon State.

========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Sean Nealon.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Clinton W. Epps, Vanessa M. Petro, Tyler G. Creech, Rachel
S. Crowhurst,
Matthew J. Weldy, Jimmy D. Taylor. Landscape Genetics of American
Beaver in Coastal Oregon. The Journal of Wildlife Management,
2021; 85 (7): 1462 DOI: 10.1002/jwmg.22102 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210830140246.htm

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