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North Bend, OR, United States

Broms K.,University of Washington | Skalski J.R.,University of Washington | Millspaugh J.J.,University of Missouri | Hagen C.A.,1374 Parrell Road | Schulz J.H.,Columbia College at Missouri
Journal of Wildlife Management | Year: 2010

Statistical population reconstruction offers a robust approach to demographic assessment for harvested populations, but current methods are restricted to big-game species with multiple age classes. We extended this approach to small game and analyzed 14 years of age-at-harvest data for greater sage-grouse (Centrocercus urophasianus) in Oregon, USA, in conjunction with radiotelemetry data to reconstruct annual abundance levels, recruitment, and natural survival probabilities. Abundance estimates ranged from a low of 26,236 in 1995 to a high of 39,492 in 2004. Annual abundance estimates for adult males were correlated with a spring lek count index (r 0.849, P < 0.029). We estimated the average annual harvest mortality for the population to be 0.028, ranging from 0.021 to 0.031 across years. We estimated the probability of natural survival of adult females to be 0.818 (SE = 0:052), somewhat higher than that of adult males (Ŝ 0.609,SE ). Our precision in reconstructing the population was hampered by low harvest rates and the few birds tagged in the radiotelemetry investigations. Despite these issues, our analysis illustrates how modern statistical reconstruction procedures offer a flexible framework for demographic assessment using commonly collected data. This approach offers a useful alternative to small-game indices and would be most appropriate for species with 5 or more years of age-at-harvest data and moderate-to-heavy harvest rates. © The Wildlife Society. Source


Hagen C.A.,1374 Parrell Road | Loughin T.M.,Simon Fraser University | Budeau D.A.,406 Cherry Avenue NE | Reishus B.S.,406 Cherry Avenue NE
Journal of Wildlife Management | Year: 2012

Ratio of immature (young of the year) grouse to adult birds (I:A) in the harvest of upland game birds is commonly used as an index to annual reproduction; however, I:A ratios can vary as the season progresses producing biased estimates. We analyzed I:A ratios in the daily harvest of dusky grouse (Dendragopus obscurus) and ruffed grouse (Bonasa umbellus) in northeastern Oregon over 28 years (1981-2008) and found that I:A ratios in the harvest declined for both species as the hunting season progressed. We also analyzed ratios of adult female to adult male (AF:AM) grouse to determine if female and male grouse were harvested in equal numbers throughout the harvest season. We found that more males than females of both species were harvested, but that AF:AM ratio of both dusky and ruffed grouse did not change during most of the hunting season. Approximately 50% of the annual harvest occurred during the first 14 days of the hunting season. Therefore, we recommend using the ratios of I:A birds in the first 14 days of the harvest season as the best index to annual reproduction of forest grouse in northeast Oregon. © 2011 The Wildlife Society. Source


Dusek R.J.,U.S. Geological Survey | Hagen C.A.,1374 Parrell Road | Hagen C.A.,Oregon State University | Franson J.C.,U.S. Geological Survey | Hofmeister E.K.,U.S. Geological Survey
Wildlife Society Bulletin | Year: 2014

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) are highly susceptible to infection with West Nile virus (WNV), with substantial mortality reported in wild populations and in experimentally infected birds. Although sage-grouse are hunted throughout much of their range, they have also recently been considered for protection under the Endangered Species Act. We used blood samples collected on filter-paper strips during the 2006-2010 Oregon, USA, annual sage-grouse hunt to survey for specific WNV-neutralizing antibodies that indicate a previous infection with WNV. During this period, hunters submitted 1,880 blood samples from sage-grouse they harvested. Samples obtained were proportional for all 12 Oregon sage-grouse hunting units. Laboratory testing of 1,839 samples by the WNV epitope-blocking enzyme-linked immunosorbent assay (bELISA) followed by plaque reduction neutralization test on bELISA-positive samples yielded 19 (1%) and 1 (0.05%) positive samples, respectively. These data provided early baseline information for future comparisons regarding the prevalence of WNV-specific neutralizing antibodies in sage-grouse in Oregon. This methodology may provide other states where sage-grouse (or other species) populations are hunted and where WNV constitutes a species conservation concern with a viable option to track the relative prevalence of the virus in populations. © 2014 The Wildlife Society. Source


Hagen C.A.,1374 Parrell Road | Hagen C.A.,Oregon State University
Wildlife Society Bulletin | Year: 2015

Biologists in Oregon, USA, have routinely collected information on forest grouse populations over a 31-year period (1981-2011) by 3 methods; however, it is unknown how well these methods detected variation in forest grouse abundance over time. We compared brood surveys, collection of hunter-harvested grouse parts (wings and tails), and hunter-harvest surveys to determine which annual survey was most useful as an index to forest grouse population trends in northeastern Oregon. All 3 surveys tracked both dusky (Dendragapus obscurus) and ruffed grouse (Bonasa umbellus) through 2 peaks in abundance separated by 14 years; however, stochastic variation resulting from small sample sizes reduced annual correlations among the methods. Grouse wing and tail collection was more informative than the other 2 indices because it exhibited the least annual variation, as well as provided estimates of both reproductive success and population size. Usefulness of hunter surveys was limited by funding, quality control, and lack of information on reproductive success. Brood surveys were the least useful of these indices because of inadequate sample sizes, particularly for ruffed grouse. The primary advantage of the brood survey was that it was available prior to the hunting season and could potentially help forecast the number of grouse available for the autumn hunting season. We recommend that grouse wing collections be continued, that consistency of hunter surveys be emphasized, and that sample size of brood surveys be increased to provide more reliable data. © The Wildlife Society, 2015. Source


Hagen C.A.,1374 Parrell Road | Willis M.J.,Eastern Oregon Agricultural Research Station | Glenn E.M.,Oregon State University | Anthony R.G.,Oregon State University
Western North American Naturalist | Year: 2011

The distribution and geographic range of Greater Sage-Grouse (Centrocercus urophasianus) have been reduced by 56% since European settlement. Although loss and fragmentation of sagebrush (Artemisia spp.) habitats have been cited as the primary causes for the decline of the species, degradation of existing habitat also has been considered an important factor. Guidelines for protection and management of breeding and winter habitat have been developed for land managers, but winter habitat use has not been thoroughly described throughout the species' range, particularly for the western portion of its range in Oregon. We examined vegetation-type selection and use by Greater Sage-Grouse during winter (Nov-Feb) at 3 study areas in southeastern Oregon (19891992). Elevation gradients and vegetative communities differed among these 3 areas. Our objective was to examine the geographic variation in the selection and use of various vegetation types during winter, when sage-grouse distributions may be most restricted. We described differences in vegetation structure at the microhabitat scale among 3 areas and differences in vegetation-type selection at the macrohabitat scale. We found that the use of mixed sagebrush (basin big sagebrush [Artemisia tridentata tridentata]) and other shrubby vegetation types by sage-grouse was greater than expected at all 3 study areas. At the low- and high-elevation study areas, low sagebrush (Artemisia longiloba) vegetation types were selected more often than expected at random, which was contrary to our original hypotheses. Basin big sagebrush vegetation types were used in proportion to their availability at the 2 low-elevation study areas, and big sagebrush steppe was used less than available (avoided) at the low-elevation areas; these results were contrary to our original predictions. Such differences in selection among the study areas in southeastern Oregon create additional challenges for land managers, who are charged with managing habitats for sage-grouse use during autumn and winter in this portion of the species' geographic range. Source

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