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Nancy E. Karraker, David S. Pilliod, Michael J. Adams, Evelyn L. Bull, Paul Stephen Corn, Lowell V. Diller, Linda A. Dupuis, Marc P. Hayes, Blake R. Hossack, Garth R. Hodgson, Erin J. Hyde, Kirk Lohman, Bradford R. Norman, Lisa M. Ollivier, Christopher A. Pearl, Charles R. Peterson
Tailed frogs (Ascaphus spp.) oviposit in cryptic locations in streams of the Pacific Northwest and Rocky Mountains. This aspect of their life history has restricted our understanding of their reproductive ecology. The recent split of A. montanus in the Rocky Mountains from A. truei was based on molecular differentiation, and comparisons of their ecology are limited. Our objectives were to provide a range-wide summary of information on Ascaphus oviposition, compare some aspects of the reproductive ecology of the 2 species, and examine geographic variation in their reproductive traits. Reproductive ecology of the 2 species differed. Ascaphus truei had smaller clutches, oviposited later in the summer, and had a longer duration of oviposition than A. montanus. A greater number of communal oviposition sites were attributed to A. montanus. These ecological differences support the recent taxonomic revision of Ascaphus and suggest that different management strategies may be necessary for each species where conservation is a priority.
Augmentation is a viable method of increasing the size of small populations if habitat quality is adequate. We examined a hierarchy of demographic responses to habitat quality, including individual nutritional condition, juvenile survival, adult fecundity, and adult survival to determine if the habitat of the Nooksack elk herd, a remnant elk population located in the northern Cascade Mountains of Washington, could support additional elk. Total ingesta-free body fat levels of lactating cow elk (11.5–13.6%), the most nutritionally challenged segment of the population, indicated that elk consumed diets at the high end of marginal quality. Juvenile survival during summer was moderate (0.66) relative to other elk populations, while annual adult survival was high (0.94). Pregnancy averaged 0.89, and early autumn calf:cow ratios ranged from 60 ± 9 to 69 ± 15 calves/100 cows. Levels of condition (approximately 56% of potential), juvenile survival (73% of potential), adult fecundity (99% of potential), and adult survival (equal to or greater than previously published survival rates) indicated habitat impacts only on the population vital rates most sensitive to nutritional stress in the Nooksack area. We conclude that the Nooksack area is capable of supporting additional elk, albeit at less than optimal levels of individual and population productivity. Further, because only a small portion of the Nooksack area that was used historically by elk is currently used, colonization of these areas used formerly by elk may also have the potential to increase numbers of elk in the Nooksack area.
Populations of western toad (Bufo boreas) have declined or disappeared from much of the species' range in the United States. To assess distributions and densities of the western toad in the foothills of west-central Alberta, Canada, we conducted visual surveys of 130 natural water bodies in watersheds encompassing a range of human-disturbance levels in early and late summer 2000. Encounter rates were consistently low throughout the study area (0.2 to 0.3 toads/h) and were one-tenth the rate for the co-occurring wood frog (Rana sylvatica). Pitfall trapping of breeding and non-breeding sites during 2001 and 2002 showed differences in age structures between western toad and wood frog populations and low recruitment of newly metamorphosed juveniles into western toad populations. On ponds, more toads of ≥1 y old were captured than recently emerged juveniles. The difference between the 2 age classes was greater on ‘borrow pits’ (human-created roadside ponds) than on beaver ponds, suggesting that borrow pits might be population sinks providing poor larval habitat. Borrow pits either dried prior to juvenile emergence or had oligotrophic to mesotrophic waters compared to eutrophic conditions in beaver ponds. Pond creation as a mitigation strategy or by-product of road construction may put western toad populations at risk of decline in the foothills of Alberta.
Information on fisher (Martes pennanti) densities is needed for the management and conservation of this mid-sized carnivore in British Columbia. To address this knowledge gap, we estimated the density of fishers in an industrial forest in north-central British Columbia between 1996 and 2000 using a minimum number alive estimate derived from live-trapping and radio-telemetry data. Density estimates averaged (± s) 11.2 ± 2.1 fishers/1000 km2 (n = 4 capture sessions) on 31 October and 8.8 ± 1.1 fishers/1000 km2 (n = 4 capture sessions) on 31 March. In comparison, the densities of fisher populations in eastern regions of North America were documented to be 6 to 49 times higher than our estimate for north-central British Columbia. The density of fishers in north-central British Columbia may be lower due to larger home range sizes and more widely dispersed individuals than elsewhere. Low-density fisher populations, such as in our study area, will require more conservative management strategies by trappers and wildlife agencies to ensure population persistence in these areas.
The objectives of this study were to document the presence of breeding populations of wood frogs (Rana sylvatica) in Denali National Park and Preserve and to examine landscape and habitat factors associated with population distribution. Surveys were conducted within 41 circular plots, each 1 km in diameter. All lentic sites were surveyed within each 1-km plot to determine the presence of wood frogs and to collect habitat data. Of the 219 sites surveyed, breeding activity (the presence of eggs or larvae) was observed at 98 sites (45%). Larger and less isolated sites had a higher incidence of observed breeding activity. Also, breeding activity was more frequently observed at sites with more emergent vegetation and more woody vegetation in the riparian zone, especially riparian zones with alder and spruce. Breeding activity was less often observed at deeper sites, sites with a permanent stream connection, sites where sphagnum (peat) dominated the substrate, and sites with beaver activity. A multifactor habitat model was developed using classification trees and parsimonious model selection protocol. The final model identified proportion of woody vegetation in the riparian zone, dominant substrate type, presence of alder in the riparian zone, and observed beaver activity as 4 habitat factors that accurately described breeding activity patterns in the study area. The results show that breeding populations of wood frogs saturate the landscape in the Wonder Lake region with nearly half of the lentic habitat sites being used by wood frogs. The majority of the sites were well into the shrubby tundra and >1000 m from boreal forest, suggesting that wood frogs in Alaska may frequent non-canopied areas at higher elevations as long as shrubby vegetation is present in riparian areas.
The largest Pacific Northwest population of bald eagles occurs in the urbanized Puget Sound. Most research and management recommendations for bald eagles have been done for forested or rural habitats. In Washington, bald eagles have been nesting in residential developments and other disturbed habitats. As required by State laws, bald eagle management plans were developed for private landowners planning on developing or clearing areas within bald eagle territories. We tested the potential effectiveness of the management plans by comparing occupancy, activity, and productivity between 30 nests with plans and 332 nests without plans. We found no significant differences between territories with and without a management plan. For another 37 nests with management plans, we found no significant change between present productivity of each nest and productivity prior to human disturbance or development near the nest area. The bald eagle plans appear to be effective in mitigating the potentially negative effects of development. Management plans prevented decreases in productivity, occupancy, and activity for Puget Sound bald eagles. Although the management plan process appears to work in the short term, there are limitations. The small core buffer areas (100 m) may not manage for long-term nest stand viability and integrity.
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