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Mountain beaver are a primitive rodent species endemic to the Pacific Northwest and California. In Oregon and Washington, mountain beaver are managed as a pest species due to the damage they inflict to Douglas-fir seedlings as well as 10- to 15-year-old trees. Available biological information on the mountain beaver is limited, thus hampering the ability of managers to develop new tools and techniques to reduce damage. We conducted a series of studies to increase our knowledge of mountain beaver biology and the influence of environmental attributes and stand management practices on demographics. Although mountain beaver damage Douglas-fir and western red cedar seedlings, observations suggest that these tree species are not preferred forage. In one pen study, pens void of preferred vegetation (i.e., salal and sword fern) had significantly more damage than pens with additional forage. Damage did not occur when animals were allowed access to pens with preferred forage, even with increased population pressure. In addition to pen trials, we radio-collared 62 mountain beaver in 3 different harvest units, which varied in vegetation management and stand age, to assess movements and seedling damage. Home ranges were larger on the chemically prepared site with reduced forage than on the non-treated site. Although mountain beaver can inhabit older timber stands, home ranges were relatively large in such stands because of the reduced preferred forage in closed-canopy habitats (3.66 ± 1.49 ha). Once units were harvested, population size increased and home range size decreased (0.88 ± 0.27 ha). Seedling damage and reproductive success were only slightly related to available forage, which was in turn affected by site preparation. Information on home range use, habitat requirements, and the difference in carrying capacity for mountain beaver under varying site preparations, can assist managers in manipulating habitats in order to minimize colonization and reduce seedling damage. We

Mountain beaver are a primitive rodent species endemic to the Pacific Northwest and California. In Oregon and Washington, mountain beaver are managed as a pest species due to the damage they inflict to Douglas-fir seedlings as well as 10- to 15-year-old trees. Available biological information on the mountain beaver is limited, thus hampering the ability of managers to develop new tools and techniques to reduce damage. We conducted a series of studies to increase our knowledge of mountain beaver biology and the influence of environmental attributes and stand management practices on demographics. Although mountain beaver damage Douglas-fir and western red cedar seedlings, observations suggest that these tree species are not preferred forage. In one pen study, pens void of preferred vegetation (i.e., salal and sword fern) had significantly more damage than pens with additional forage. Damage did not occur when animals were allowed access to pens with preferred forage, even with increased population pressure. In addition to pen trials, we radio-collared 62 mountain beaver in 3 different harvest units, which varied in vegetation management and stand age, to assess movements and seedling damage. Home ranges were larger on the chemically prepared site with reduced forage than on the non-treated site. Although mountain beaver can inhabit older timber stands, home ranges were relatively large in such stands because of the reduced preferred forage in closed-canopy habitats (3.66 ± 1.49 ha). Once units were harvested, population size increased and home range size decreased (0.88 ± 0.27 ha). Seedling damage and reproductive success were only slightly related to available forage, which was in turn affected by site preparation. Information on home range use, habitat requirements, and the difference in carrying capacity for mountain beaver under varying site preparations, can assist managers in manipulating habitats in order to minimize colonization and reduce seedling damage. We

The mountain beaver is a fossorial rodent species endemic to the Pacific Northwest and portions of California. This herbivore is managed as a pest species because of the impact it has on newly planted Douglas-fir seedlings. Currently, managers are limited to trapping for population control; however, in Washington trapping has been further curtailed by anti-trapping legislation. Presently there are no registered underground toxicants for mountain beaver control. We have documented the efficacy of chlorophacinone, presented in daily doses, as a possible alternative for mountain beaver control. Daily baiting would be unreasonable and costly alternative for timber managers, so we conducted a series of tests to determine if a single or double baiting was efficacious. In addition, we tested the caching behavior of the mountain beaver when offered bags of oats. This behavior may help reduce impacts to non-target species as well reduce environmental exposure and degradation. Mountain beaver readily cached bags of chlorophacinone within their artificial burrows, and efficacy of a one-time and two-time dose was 100%. We determined that even with the highest chlorophacinone residuals (0.354 ppm) that the risk quotient for mink and red-tailed hawk was exactly at the level of concern that EPA recognizes for endangered and threatened species.

The mountain beaver is a semi-fossorial rodent of the Pacific Northwest and is among a variety of herbivores that retard plant growth and cause tree seedling deformities and mortality. Douglas-fir seedlings are planted in the Pacific Northwest from February through March, a period coinciding with mountain beaver parturition. Previous research suggested that in spring, lactating females depend more on conifers than do non-lactating females and males. We conducted experiments to determine if female reproductive condition influenced seedling damage, and if physiological stage of the seedling affected damage. Dormant and flushing trees were offered to 6 pregnant and 6 non-pregnant females in 2002 and 2003. We found no difference between female condition and damage in 2002, but there was a significant difference between type of tree and damage (F6,79 = 6.75, P < 0.001). In 2003, we found a difference in seedling damage (F3,95 = 16.41, P < 0.001), with tree type (P < 0.001) and female condition (P = 0.02) contributing to the model. More flushing trees were damaged in both years than dormant trees, once bud break occurred. Statistical analyses of fructose (F5,23 = 12.07, P < 0.001) and glucose (F5,23 = 12.86, P < 0.001) concentration data indicate that tree type (dormant or flushing) was a significant effect (P < 0.001). The interaction between tree type and week sampled was also significant in both the glucose (P = 0.002) and fructose response (P = 0.009). Both fructose and glucose concentrations were the lowest in new flushing trees, and mountain beaver did not appear to be selecting flushing trees for their needle sugar content. Water concentration also varied between tree type but was not affected by the sampling time (F5,20 = 35.46, P < 0.001). New and dormant growth tissues had similar water concentrations that were greater than old growth tissue. Mountain beaver are dependent upon a constant water source, although it does not appear that damage

The mountain beaver is a semi-fossorial rodent of the Pacific Northwest and is among a variety of herbivores that retard plant growth and cause tree seedling deformities and mortality. Douglas-fir seedlings are planted in the Pacific Northwest from February through March, a period coinciding with mountain beaver parturition. Previous research suggested that in spring, lactating females depend more on conifers than do non-lactating females and males. We conducted experiments to determine if female reproductive condition influenced seedling damage, and if physiological stage of the seedling affected damage. Dormant and flushing trees were offered to 6 pregnant and 6 non-pregnant females in 2002 and 2003. We found no difference between female condition and damage in 2002, but there was a significant difference between type of tree and damage (F6,79 = 6.75, P < 0.001). In 2003, we found a difference in seedling damage (F3,95 = 16.41, P < 0.001), with tree type (P < 0.001) and female condition (P = 0.02) contributing to the model. More flushing trees were damaged in both years than dormant trees, once bud break occurred. Statistical analyses of fructose (F5,23 = 12.07, P < 0.001) and glucose (F5,23 = 12.86, P < 0.001) concentration data indicate that tree type (dormant or flushing) was a significant effect (P < 0.001). The interaction between tree type and week sampled was also significant in both the glucose (P = 0.002) and fructose response (P = 0.009). Both fructose and glucose concentrations were the lowest in new flushing trees, and mountain beaver did not appear to be selecting flushing trees for their needle sugar content. Water concentration also varied between tree type but was not affected by the sampling time (F5,20 = 35.46, P < 0.001). New and dormant growth tissues had similar water concentrations that were greater than old growth tissue. Mountain beaver are dependent upon a constant water source, although it does not appear that damage

The mountain beaver is a fossorial rodent species endemic to the Pacific Northwest and portions of California. This herbivore is managed as a pest species because of the impact it has on newly planted Douglas-fir seedlings. Currently, managers are limited to trapping for population control; however, in Washington trapping has been further curtailed by anti-trapping legislation. Presently there are no registered underground toxicants for mountain beaver control. We have documented the efficacy of chlorophacinone, presented in daily doses, as a possible alternative for mountain beaver control. Daily baiting would be unreasonable and costly alternative for timber managers, so we conducted a series of tests to determine if a single or double baiting was efficacious. In addition, we tested the caching behavior of the mountain beaver when offered bags of oats. This behavior may help reduce impacts to non-target species as well reduce environmental exposure and degradation. Mountain beaver readily cached bags of chlorophacinone within their artificial burrows, and efficacy of a one-time and two-time dose was 100%. We determined that even with the highest chlorophacinone residuals (0.354 ppm) that the risk quotient for mink and red-tailed hawk was exactly at the level of concern that EPA recognizes for endangered and threatened species.

High deer densities increase vehicle collisions, damage agricultural crops, and amplify the spread of zoonotic and animal diseases, intensifying human-deer conflict. In addition, deer impact on forest vegetation can influence the distribution and abundance of other wildlife species. Greater demand for non-lethal means of animal damage control has led to an interest in contraception as a wildlife management tool. The development of a single-injection Gonadotropin-Releasing Hormone (GnRH) contraceptive vaccine by NWRC reduces logistical limitations and cost of using immunocontraception as compared to a vaccine that requires two injections. This study assessed the efficacy of two different GnRH-KLH (keyhole limpet hemocyanin) vaccine designs in a single-injection study, to determine if Mycobacterium avium bacterium in the adjuvant is necessary for the success of a single-injection contraceptive vaccine. Forty-two captive female black-tailed deer were divided into 3 groups. Control deer were injected with saline solution, one treatment group received GonaCon™ (a GnRH-KLH vaccine paired with AdjuVac™ adjuvant that contains a small quantity of killed M. avium bacterium), and the second treatment group received GnRH-KLH vaccine with DEAE-Dextran/oil as the adjuvant. Contraceptive success was evaluated by monitoring progesterone, pregnancy specific protein, antibodies to GnRH-KLH conjugate and to Johne’s bacterium (M. avium), and actual pregnancy rates. Pregnancy rates were significantly different based on treatment (X² = 9.389; df = 2; P = 0.009). Pregnancy rates in deer treated with GonaCon™ were significantly reduced as compared to saline controls (P = 0.006), but there was no significant difference between GnRH-DD compared to saline (P = 0.297). Significant difference was found between GonaCon™ and GnRH-DD (P = 0.055). Results suggest that M. avium in the AdjuVac™ adjuvant is essential for the success of the single-injection GnRH vaccine GonaCon™. The development of a s

Population reduction measures need to be implemented to reforestation plots infested with pocket gopher in the Pacific Northwest. This 1-year investigation assessed the efficacy of 0.15% cholecalciferol (vitamin D3) bait application to reduce pocket gophers and the long-term effects on non-target small rodent populations within treated plots. The study site was a reforested clear cut containing pocket gopher populations of 10 to 14 animals per ha. Six plots (2.8 ha each) were randomly selected at the study site, 3 plots of untreated controls and 3 plots baited with cholecalciferol. A trap-and-release program was used to assess non-target populations. Radio telemetry and the open hole method were used to monitor pocket gopher activity before and after the fall application of cholecalciferol bait. A 70-80% reduction of pocket gopher activity from telemetered animals occurred in the treated plots, whereas only 10-20% mortality occurred on the control plots. Pocket gopher activity in most of the plots increased by June, and by September of the following year, activity was back to original levels. Time, not treatment, had a significant effect on yellow pine chipmunk, Townsend chipmunk, and golden-mantled ground squirrel populations. We conclude that 0.15% cholecalciferol bait appears to have application for pocket gopher control. Risks to non-target species may exist.

High deer densities increase vehicle collisions, damage agricultural crops, and amplify the spread of zoonotic and animal diseases, intensifying human-deer conflict. In addition, deer impact on forest vegetation can influence the distribution and abundance of other wildlife species. Greater demand for non-lethal means of animal damage control has led to an interest in contraception as a wildlife management tool. The development of a single-injection Gonadotropin-Releasing Hormone (GnRH) contraceptive vaccine by NWRC reduces logistical limitations and cost of using immunocontraception as compared to a vaccine that requires two injections. This study assessed the efficacy of two different GnRH-KLH (keyhole limpet hemocyanin) vaccine designs in a single-injection study, to determine if Mycobacterium avium bacterium in the adjuvant is necessary for the success of a single-injection contraceptive vaccine. Forty-two captive female black-tailed deer were divided into 3 groups. Control deer were injected with saline solution, one treatment group received GonaCon™ (a GnRH-KLH vaccine paired with AdjuVac™ adjuvant that contains a small quantity of killed M. avium bacterium), and the second treatment group received GnRH-KLH vaccine with DEAE-Dextran/oil as the adjuvant. Contraceptive success was evaluated by monitoring progesterone, pregnancy specific protein, antibodies to GnRH-KLH conjugate and to Johne’s bacterium (M. avium), and actual pregnancy rates. Pregnancy rates were significantly different based on treatment (X² = 9.389; df = 2; P = 0.009). Pregnancy rates in deer treated with GonaCon™ were significantly reduced as compared to saline controls (P = 0.006), but there was no significant difference between GnRH-DD compared to saline (P = 0.297). Significant difference was found between GonaCon™ and GnRH-DD (P = 0.055). Results suggest that M. avium in the AdjuVac™ adjuvant is essential for the success of the single-injection GnRH vaccine GonaCon™. The development of a s

Population reduction measures need to be implemented to reforestation plots infested with pocket gopher in the Pacific Northwest. This 1-year investigation assessed the efficacy of 0.15% cholecalciferol (vitamin D3) bait application to reduce pocket gophers and the long-term effects on non-target small rodent populations within treated plots. The study site was a reforested clear cut containing pocket gopher populations of 10 to 14 animals per ha. Six plots (2.8 ha each) were randomly selected at the study site, 3 plots of untreated controls and 3 plots baited with cholecalciferol. A trap-and-release program was used to assess non-target populations. Radio telemetry and the open hole method were used to monitor pocket gopher activity before and after the fall application of cholecalciferol bait. A 70-80% reduction of pocket gopher activity from telemetered animals occurred in the treated plots, whereas only 10-20% mortality occurred on the control plots. Pocket gopher activity in most of the plots increased by June, and by September of the following year, activity was back to original levels. Time, not treatment, had a significant effect on yellow pine chipmunk, Townsend chipmunk, and golden-mantled ground squirrel populations. We conclude that 0.15% cholecalciferol bait appears to have application for pocket gopher control. Risks to non-target species may exist.