BEAVERS: NATURE’S ECOSYSTEM ENGINEERS   By Torrey Ritter

Beavers exert profound influence on the wetland and riparian habitats they occupy through the construction of dams and lodges, digging of tunnels and channels, and removal and redistributionof woody riparian vegetation.While the effects of beavers occupying an area can vary widely, in smaller headwater stream systems beaver activities expand and maintain healthy and productive riparian and wetland habitats. Beavers have been identified as a keystone species and an ecosystem engineer because they drastically modify the habitats they occupy and in doing so create environmental conditions that allow certain plant and animals species to inhabit an area where they may not otherwise occur. Bird species are especially impacted, as beaver activity creates patches of wetland habitats in what are many times dry and arid landscapes. These habitat patches support a variety of nesting and brood-rearing habitats for birds as well as productive foraging areas. It has been postulated that ecosystem engineers such as beavers contribute significantly to patch-level and landscape-level habitat heterogeneity and can therefore increase overall species richness and diversity at the landscape scale. As a result, the use of beavers or beaver mimicry for wetland and riparian habitat restoration has dramatically increased in popularity over the past 30 years.

Juvenile beavers disperse from their natal colonies at 1−3 years of age and head out on their own to start a new colony. The natural dispersal and settlement process provides the best opportunity to study an aspect of beaver life history that is most relatable to restoration projects. Beaver restoration projects often involve encouraging beavers to colonize an area that is relatively un-modified by previous beaver activity and is suboptimal in terms of habitat quality, a situation encountered by many dispersing beavers. In 2015, researchers at Montana State University undertook a 2.5-year project aimed at better understanding the ecology of beavers in relation to habitat restoration strategies. Researchers radio-marked dispersal-age beavers and followed them throughout the dispersal process to evaluate dispersal distances, timing, and outcomes. Concurrently, the researchers mapped beaver activity in the headwaters of two major river drainages to evaluate habitat preferences of beavers starting new colonies in novel areas. This mapping effort also allowed the researchers to assess the influence of colony densities and the availability of territories on the dispersal and settlement process. Torrey Ritter, the graduate student leading this project, will present the results of this project as well as outline the impact of beavers on ecosystems in the western United States and associated wildlife species.

Torrey grew up in Wyoming and Idaho but has spent most of his life in the Bitterroot and Gallatin Valleys in Montana. Torrey grew up with a wildlife biologist mom and a forester dad, and spent most of his childhood fishing and hiking in the mountains and learning about the natural world from his wonderful parents. Torrey graduated from MSU in 2009 with a degree in Organismal Biology and spent the next 6 years working on a wide variety of wildlife-related research projects. Torrey started his wildlife work on Region 3 MWFP Wildlife Management Areas conducting survey and inventory of game and non-game species, trapping small mammals to evaluate the influence of rest-rotation grazing systems, and conducting beaver occupancy and distribution surveys. He also worked as a Block Management technician, evaluated pre-nesting diet selection in sage grouse, surveyed nest occupancy and success for bald eagles and peregrine falcons, tracked pregnant radio-collared elk to evaluate disease dynamics, surveyed whitebark pine in high elevations within the Greater Yellowstone Ecosystem, and conducted hair snare sampling for grizzly bears in Grand Teton National Park. In 2015, Torrey was hired for his dream project investigating dispersal and habitat selection of beavers in the context of beaver-mediated habitat restoration. Torrey just completed his graduate degree in Animal and Range Sciences at Montana State University under the guidance of Dr. Lance McNew in the Wildlife Habitat Ecology Lab. Torrey plans on remaining in Montana and continuing to research beavers and advocate for beaver restoration.

TO HEAR TORREY DESCRIBE THIS FASCINATING RESEARCH AND WHAT WAS LEARNED, JOIN BITTERROOT AUDUBON MONDAY, APRIL 16^TH7:00 P.M. AT THE FOREST SERVICE/NATURAL RESOURCES BUILDING, 1801 NORTH 1^ST(north end of Hamilton west side of HWY 93). Enter the building on the west side. THE PUBLIC IS INVITED. Contact Kay Fulton for additional information (360-8664).