Abstract Between 2007 and 2021 we monitored adult hawks (Buteo spp.) nesting in the upper Columbia River Basin of Washington and Oregon using global positioning system (GPS) telemetry on 17 Ferruginous Hawks (B. regalis), 9 Red-tailed Hawks (B. jamaicensis), and 14 Swainson's Hawks (B. swainsoni). Our main objectives were to: (1) provide contemporary home-range estimates using fixes generated by the global positioning system to better inform protective buffers on Buteo ranges in the Columbia River Basin; and (2) describe prey analyzed from pellets collected at 47 Buteo territories. Breeding home ranges (Brownian bridge movement model, 95% isopleths) of Ferruginous Hawks (B. regalis) were substantially larger (x̄ = 378, sx = 133 km2) than those published previously, as were home ranges of Swainson's Hawks (x̄ = 276, sx = 146 km2) and Red-tailed Hawks (x̄ = 28, sx = 12 km2). Diets of Ferruginous Hawks on the study area were dominated (60%) by Northern Pocket Gophers (Thomomys talpoides), whereas Swainson's Hawks primarily (83%) ate grasshoppers (Apote notablis and Melanoplus spp.). Red-tailed Hawks ate a less-specialized diet of reptiles (40%), mammals (38%), and birds (13%). We provide models that show the probable degree of protection afforded by different-sized buffers when applied to species-specific home ranges and core areas for hawks in the Columbia River Basin.
{"title":"CONTRASTING HOME RANGE CHARACTERISTICS AND PREY OF SYMPATRIC HAWKS (BUTEO SPP) NESTING IN THE UPPER COLUMBIA RIVER BASIN","authors":"J. W. Watson, Robert W Davies, Patrick S. Kolar","doi":"10.1898/NWN22-07","DOIUrl":"https://doi.org/10.1898/NWN22-07","url":null,"abstract":"Abstract Between 2007 and 2021 we monitored adult hawks (Buteo spp.) nesting in the upper Columbia River Basin of Washington and Oregon using global positioning system (GPS) telemetry on 17 Ferruginous Hawks (B. regalis), 9 Red-tailed Hawks (B. jamaicensis), and 14 Swainson's Hawks (B. swainsoni). Our main objectives were to: (1) provide contemporary home-range estimates using fixes generated by the global positioning system to better inform protective buffers on Buteo ranges in the Columbia River Basin; and (2) describe prey analyzed from pellets collected at 47 Buteo territories. Breeding home ranges (Brownian bridge movement model, 95% isopleths) of Ferruginous Hawks (B. regalis) were substantially larger (x̄ = 378, sx = 133 km2) than those published previously, as were home ranges of Swainson's Hawks (x̄ = 276, sx = 146 km2) and Red-tailed Hawks (x̄ = 28, sx = 12 km2). Diets of Ferruginous Hawks on the study area were dominated (60%) by Northern Pocket Gophers (Thomomys talpoides), whereas Swainson's Hawks primarily (83%) ate grasshoppers (Apote notablis and Melanoplus spp.). Red-tailed Hawks ate a less-specialized diet of reptiles (40%), mammals (38%), and birds (13%). We provide models that show the probable degree of protection afforded by different-sized buffers when applied to species-specific home ranges and core areas for hawks in the Columbia River Basin.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122552649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Reported herein is the behavior of an American Crow (Corvus brachyrhynchos) that was photographed dunking and paddling a cracker in a birdbath. It is reasonable to assert that the birdbath's water was used to moisten and/or soften the hard and dry cracker prior to consumption. Additionally, this problem-solving behavior appears to have been premeditated, given how deliberate the crow was with each step of its behavior.
{"title":"CORVID WANTS A CRACKER","authors":"P. Gorman","doi":"10.1898/nwn22-11","DOIUrl":"https://doi.org/10.1898/nwn22-11","url":null,"abstract":"Abstract Reported herein is the behavior of an American Crow (Corvus brachyrhynchos) that was photographed dunking and paddling a cracker in a birdbath. It is reasonable to assert that the birdbath's water was used to moisten and/or soften the hard and dry cracker prior to consumption. Additionally, this problem-solving behavior appears to have been premeditated, given how deliberate the crow was with each step of its behavior.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116811080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Facultative mutualism between a Black-billed Magpie (Pica hudsonia) and a Rocky Mountain Elk (Cervus canadensis nelson) is reported. This interspecific interaction was observed in Yellowstone National Park, Wyoming, and was documented photographically.
{"title":"MAGPIE AND MUTUALISM: PHOTOGRAPHIC EVIDENCE","authors":"P. Gorman","doi":"10.1898/NWN21-06","DOIUrl":"https://doi.org/10.1898/NWN21-06","url":null,"abstract":"Abstract Facultative mutualism between a Black-billed Magpie (Pica hudsonia) and a Rocky Mountain Elk (Cervus canadensis nelson) is reported. This interspecific interaction was observed in Yellowstone National Park, Wyoming, and was documented photographically.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117254029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laura B. Guderyahn, E. M. Stewart, S. Beilke, C. D. de Rivera, M. Hayes
Abstract Western Painted Turtles (Chrysemys picta bellii) are 1 of only 2 native turtles in the Pacific Northwest. In October 2021, we recaptured an adult male 21 y after it was initially marked. In 2000, it had at least 9 annuli, indicating an age of at least 30 y in 2021. This approximates only half the maximum known age for the larger C. picta species complex east of the continental divide (61 y). Further, in 2000, this adult male was 37–43 mm larger than the largest or oldest males recorded from eastern populations of C. p. bellii, which suggests that fundamental differences may exist in growth between eastern and western populations that may reflect different age-size relationships. These relationships, along with longevity data, are foundational to conservation that seeks to understand demography and survival in western populations. Study of eastern populations shows that determination of age limits may span decades, so collaboration for data-sharing over long timelines to understand the patterns in western populations will be crucial.
{"title":"LONG-TERM RECAPTURE OF WESTERN PAINTED TURTLE (CHRYSEMYS PICTA BELLII): LONGEVITY IMPLICATIONS","authors":"Laura B. Guderyahn, E. M. Stewart, S. Beilke, C. D. de Rivera, M. Hayes","doi":"10.1898/NWN22-09","DOIUrl":"https://doi.org/10.1898/NWN22-09","url":null,"abstract":"Abstract Western Painted Turtles (Chrysemys picta bellii) are 1 of only 2 native turtles in the Pacific Northwest. In October 2021, we recaptured an adult male 21 y after it was initially marked. In 2000, it had at least 9 annuli, indicating an age of at least 30 y in 2021. This approximates only half the maximum known age for the larger C. picta species complex east of the continental divide (61 y). Further, in 2000, this adult male was 37–43 mm larger than the largest or oldest males recorded from eastern populations of C. p. bellii, which suggests that fundamental differences may exist in growth between eastern and western populations that may reflect different age-size relationships. These relationships, along with longevity data, are foundational to conservation that seeks to understand demography and survival in western populations. Study of eastern populations shows that determination of age limits may span decades, so collaboration for data-sharing over long timelines to understand the patterns in western populations will be crucial.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129815823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carter J Johnson, J. Hale, M. Tinker, Erin U Foster, J. Samhouri, A. Shelton, K. Laidre
Abstract As animal populations approach environmental carrying capacity, competition for food increases, generally leading to decreased individual energy intake rate. Energy-intake rate can therefore be used as one metric of population status relative to carrying capacity. Focal observations of Sea Otter (Enhydra lutris) foraging behavior have been used throughout their range to estimate energy-intake rates and infer population status. In Washington State, previous research has demonstrated that handling times for Kelp Crabs (Pugettia spp.) by Sea Otters are 1.5 to 2 times faster than those observed in California and British Columbia, resulting in higher energy-intake rate estimates for Sea Otters in Washington. We investigated potential causes for the difference in handling time by: (1) comparing Sea Otter handling times of Kelp Crab and non-Kelp Crab prey items in Washington, California, and British Columbia; (2) comparing the handling times of Kelp Crabs by a subset of Sea Otters in California, which are Kelp Crab specialists (2003–2012, n = 244 Kelp Crab captures) to those of Sea Otters in Washington (2015–2018, n = 541 captures) and British Columbia (2013–2017, n = 359 captures); and (3) comparing the biomass-to-width ratios of Kelp Crabs from Washington and California. We did not observe consistent differences between regions in Sea Otter handling times of non-Kelp Crab prey. Mean Sea Otter handling time of small Kelp Crabs (carapace ≤1 Sea Otter paw width) in Washington (32.7 s) was significantly faster than in British Columbia (52.0 s, P < 0.0001) and all of California (40.6 s, P < 0.0001), but was not significantly different from that of Kelp Crab-specialist Sea Otters in California (31.7 s, P = 0.313). Mean Sea Otter handling time of large Kelp Crabs (≥1 Sea Otter paw) in Washington (64.7 s) was significantly faster than in British Columbia (87.7 s, P= 0.003), in all of California (104 s, P < 0.0001), and in the subset of Kelp Crab-specialist Sea Otters in California (91.6 s, P = 0.007). Kelp Crabs in Washington had a larger biomass-to-width ratio than Kelp Crabs in California: in Washington, a Kelp Crab with a 20-mm maximum carapace width had a 3.8% greater predicted biomass than a Kelp Crab in California of the same width, and a 27.1% greater biomass for a 60-mm carapace. Our results suggest that Sea Otters in Washington are Kelp Crab specialists with behavioral differences allowing them to consume Kelp Crabs faster, a difference that may affect the inference of Sea Otter population status from energy-intake rates in Washington.
当动物种群接近环境承载能力时，对食物的竞争加剧，通常导致个体能量摄取率下降。因此，能量摄取率可以作为相对于承载能力的人口状况的一个度量标准。通过对海獭(Enhydra lutris)觅食行为的局部观察，可以估计其能量摄取率并推断种群状况。在华盛顿州，先前的研究表明，海獭处理海带蟹(Pugettia spp.)的时间比在加利福尼亚州和不列颠哥伦比亚省观察到的要快1.5到2倍，这导致华盛顿海獭的能量摄取率估计更高。本研究通过对华盛顿州、加利福尼亚州和不列颠哥伦比亚省海獭对海带蟹和非海带蟹猎物的处理时间进行比较，探讨了海獭处理时间差异的潜在原因;(2)比较加利福尼亚州海獭(2003-2012年，n = 244只海獭捕获海带蟹)与华盛顿州海獭(2015-2018年，n = 541只)和不列颠哥伦比亚省海獭(2013-2017年，n = 359只)对海带蟹的处理次数;(3)比较华盛顿州和加利福尼亚州海带蟹的生物量与宽度比。我们没有观察到海獭处理非海带蟹猎物的时间在区域之间的一致性差异。华盛顿州小海带蟹(甲壳≤1海獭掌宽)的平均海獭处理时间(32.7 s)显著快于不列颠哥伦比亚省(52.0 s, P < 0.0001)和加利福尼亚州(40.6 s, P < 0.0001)，但与加利福尼亚州海带蟹专业海獭(31.7 s, P = 0.313)差异不显著。华盛顿州海獭处理大型海獭蟹(≥1个海獭爪)的平均时间(64.7 s)显著快于不列颠哥伦比亚省(87.7 s, P= 0.003)、加利福尼亚州(104 s, P < 0.0001)和加利福尼亚州海獭专业海獭亚群(91.6 s, P= 0.007)。华盛顿的海带蟹比加州的海带蟹具有更大的生物量与宽度比:在华盛顿，最大壳宽为20毫米的海带蟹的预测生物量比相同宽度的加州海带蟹高3.8%，60毫米的海带蟹的生物量比加州海带蟹高27.1%。我们的研究结果表明，华盛顿的海獭是海带蟹专家，它们的行为差异使它们能够更快地消耗海带蟹，这一差异可能会影响华盛顿海獭种群状况的能量摄取率推断。
{"title":"RAPID CONSUMPTION OF KELP CRAB: IMPLICATIONS FOR SEA OTTERS IN WASHINGTON STATE","authors":"Carter J Johnson, J. Hale, M. Tinker, Erin U Foster, J. Samhouri, A. Shelton, K. Laidre","doi":"10.1898/NWN20-07","DOIUrl":"https://doi.org/10.1898/NWN20-07","url":null,"abstract":"Abstract As animal populations approach environmental carrying capacity, competition for food increases, generally leading to decreased individual energy intake rate. Energy-intake rate can therefore be used as one metric of population status relative to carrying capacity. Focal observations of Sea Otter (Enhydra lutris) foraging behavior have been used throughout their range to estimate energy-intake rates and infer population status. In Washington State, previous research has demonstrated that handling times for Kelp Crabs (Pugettia spp.) by Sea Otters are 1.5 to 2 times faster than those observed in California and British Columbia, resulting in higher energy-intake rate estimates for Sea Otters in Washington. We investigated potential causes for the difference in handling time by: (1) comparing Sea Otter handling times of Kelp Crab and non-Kelp Crab prey items in Washington, California, and British Columbia; (2) comparing the handling times of Kelp Crabs by a subset of Sea Otters in California, which are Kelp Crab specialists (2003–2012, n = 244 Kelp Crab captures) to those of Sea Otters in Washington (2015–2018, n = 541 captures) and British Columbia (2013–2017, n = 359 captures); and (3) comparing the biomass-to-width ratios of Kelp Crabs from Washington and California. We did not observe consistent differences between regions in Sea Otter handling times of non-Kelp Crab prey. Mean Sea Otter handling time of small Kelp Crabs (carapace ≤1 Sea Otter paw width) in Washington (32.7 s) was significantly faster than in British Columbia (52.0 s, P < 0.0001) and all of California (40.6 s, P < 0.0001), but was not significantly different from that of Kelp Crab-specialist Sea Otters in California (31.7 s, P = 0.313). Mean Sea Otter handling time of large Kelp Crabs (≥1 Sea Otter paw) in Washington (64.7 s) was significantly faster than in British Columbia (87.7 s, P= 0.003), in all of California (104 s, P < 0.0001), and in the subset of Kelp Crab-specialist Sea Otters in California (91.6 s, P = 0.007). Kelp Crabs in Washington had a larger biomass-to-width ratio than Kelp Crabs in California: in Washington, a Kelp Crab with a 20-mm maximum carapace width had a 3.8% greater predicted biomass than a Kelp Crab in California of the same width, and a 27.1% greater biomass for a 60-mm carapace. Our results suggest that Sea Otters in Washington are Kelp Crab specialists with behavioral differences allowing them to consume Kelp Crabs faster, a difference that may affect the inference of Sea Otter population status from energy-intake rates in Washington.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127900833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-17DOI: 10.1898/1051-1733-103.3.236
A. Stratton, Read Barbee, K. Sager-Fradkin, Bethany Tropp Ackerman, L. Elbroch
Abstract Anecdotal and quantitative evidence of the Cougar's (Puma concolor) ability to swim across large bodies of water remains limited in the scientific literature. Here we report a 1.1-km swim by a dispersing male Cougar from the Olympic Peninsula to Squaxin Island in Puget Sound, Washington. We then predict the total number of islands in the Salish Sea that may be accessible to Cougars via swimming, using this Cougar's movement as a potential upper threshold distance, and present sightings records from islands in the Salish Sea to confirm or refute our results. We estimated that 3808 of 6153 islands in the Salish Sea could be accessible to Cougars with ≥1 or more 1.1-km swims, and we confirmed Cougar presence on 18 of those islands. Four islands with confirmed sightings required swims closer to 2 km. Increasing the threshold distance to 2 km yielded an additional 775 potentially accessible islands, including the 4 not captured by the 1.1-km threshold. Cougars are an umbrella species used to identify wildlife corridors across their range. We believe that improving our understanding of Cougar swimming abilities will aid us in determining the extent of habitat connectivity existing in the Pacific Northwest, where current habitat fragmentation characteristic of the Anthropocene may threaten Cougar metapopulation connectivity important to maintaining genetic health of the species.
{"title":"ISLAND HOPPING COUGARS (PUMA CONCOLOR) IN THE SALISH SEA","authors":"A. Stratton, Read Barbee, K. Sager-Fradkin, Bethany Tropp Ackerman, L. Elbroch","doi":"10.1898/1051-1733-103.3.236","DOIUrl":"https://doi.org/10.1898/1051-1733-103.3.236","url":null,"abstract":"Abstract Anecdotal and quantitative evidence of the Cougar's (Puma concolor) ability to swim across large bodies of water remains limited in the scientific literature. Here we report a 1.1-km swim by a dispersing male Cougar from the Olympic Peninsula to Squaxin Island in Puget Sound, Washington. We then predict the total number of islands in the Salish Sea that may be accessible to Cougars via swimming, using this Cougar's movement as a potential upper threshold distance, and present sightings records from islands in the Salish Sea to confirm or refute our results. We estimated that 3808 of 6153 islands in the Salish Sea could be accessible to Cougars with ≥1 or more 1.1-km swims, and we confirmed Cougar presence on 18 of those islands. Four islands with confirmed sightings required swims closer to 2 km. Increasing the threshold distance to 2 km yielded an additional 775 potentially accessible islands, including the 4 not captured by the 1.1-km threshold. Cougars are an umbrella species used to identify wildlife corridors across their range. We believe that improving our understanding of Cougar swimming abilities will aid us in determining the extent of habitat connectivity existing in the Pacific Northwest, where current habitat fragmentation characteristic of the Anthropocene may threaten Cougar metapopulation connectivity important to maintaining genetic health of the species.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134382947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-17DOI: 10.1898/1051-1733-103.3.266
P. Gorman
Abstract Reported herein is the demonstration of flock and pair bonds by members of a Wild Turkey (Meleagris gallopavo) rafter. This demonstration was observed following the fatal vehicle strike of one of the rafter's members.
{"title":"WHY DID THE TURKEY CROSS THE ROAD? EVIDENCE OF BONDS AMONG WILD TURKEYS","authors":"P. Gorman","doi":"10.1898/1051-1733-103.3.266","DOIUrl":"https://doi.org/10.1898/1051-1733-103.3.266","url":null,"abstract":"Abstract Reported herein is the demonstration of flock and pair bonds by members of a Wild Turkey (Meleagris gallopavo) rafter. This demonstration was observed following the fatal vehicle strike of one of the rafter's members.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121395641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-17DOI: 10.1898/1051-1733-103.3.250
Marie I. Tosa, D. B. Lesmeister, Taal Levi
Abstract The potential for trophic cascades triggered by recent range expansion of the Barred Owl (Strix varia) to the Pacific Northwest has caused concern among conservationists and managers. Barred Owl predation of small forest carnivores is a particular concern because these carnivores typically have low population growth rates relative to their body size owing to long interbirth intervals, which may result in sensitivity to increased mortality. The Western Spotted Skunk (Spilogale gracilis) is a common small carnivore in forests of the Pacific Northwest that may be a prey item for Barred Owls, and previous research suggests that avian predation can be a primary cause of mortality for congeneric spotted skunks (Spilogale spp.). We report a confirmed predation event of a Western Spotted Skunk by a Barred Owl and 3 additional predation events that we suspect were due to Barred Owls based on circumstantial evidence. During a Western Spotted Skunk research study, we recovered the radio collar of an adult male skunk from the top of a tall snag and located intestines and avian feces at the base of this snag. DNA metabarcoding revealed that the avian feces contained Western Spotted Skunk and Barred Owl DNA. Barred Owls are a novel predator of the Western Spotted Skunk in forests of the Pacific Northwest and may have both direct and indirect negative impacts on Western Spotted Skunk populations.
{"title":"BARRED OWL PREDATION OF WESTERN SPOTTED SKUNKS","authors":"Marie I. Tosa, D. B. Lesmeister, Taal Levi","doi":"10.1898/1051-1733-103.3.250","DOIUrl":"https://doi.org/10.1898/1051-1733-103.3.250","url":null,"abstract":"Abstract The potential for trophic cascades triggered by recent range expansion of the Barred Owl (Strix varia) to the Pacific Northwest has caused concern among conservationists and managers. Barred Owl predation of small forest carnivores is a particular concern because these carnivores typically have low population growth rates relative to their body size owing to long interbirth intervals, which may result in sensitivity to increased mortality. The Western Spotted Skunk (Spilogale gracilis) is a common small carnivore in forests of the Pacific Northwest that may be a prey item for Barred Owls, and previous research suggests that avian predation can be a primary cause of mortality for congeneric spotted skunks (Spilogale spp.). We report a confirmed predation event of a Western Spotted Skunk by a Barred Owl and 3 additional predation events that we suspect were due to Barred Owls based on circumstantial evidence. During a Western Spotted Skunk research study, we recovered the radio collar of an adult male skunk from the top of a tall snag and located intestines and avian feces at the base of this snag. DNA metabarcoding revealed that the avian feces contained Western Spotted Skunk and Barred Owl DNA. Barred Owls are a novel predator of the Western Spotted Skunk in forests of the Pacific Northwest and may have both direct and indirect negative impacts on Western Spotted Skunk populations.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123871215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Grizzly Bears (Ursus arctos) are protected in the contiguous United States under the federal Endangered Species Act. The conservation strategy for the species encourages population connectivity between isolated Grizzly Bear Recovery Areas through Demographic Connectivity Areas. Another goal is reestablishment of a breeding population in the Bitterroot ecosystem through natural immigration. Using the locations of 362 verified Grizzly Bear den sites and Maxent as a resource selection function, we predicted 21,091 km2 of suitable denning habitats. Terrain features, distance to roads, and land cover best explained suitable denning habitats in northern Idaho and western Montana. The results support the demographic model for population connectivity, and independent of other factors there is suitable denning habitat for hundreds of Grizzly Bears in the Bitterroot analysis area. We suggest additions to the Bitterroot Grizzly Bear Recovery Area, and that more effective motorized-access management be applied to demographic connectivity areas.
{"title":"GRIZZLY BEAR DENNING HABITAT AND DEMOGRAPHIC CONNECTIVITY IN NORTHERN IDAHO AND WESTERN MONTANA","authors":"Michael Bader, Paul Sieracki","doi":"10.1898/NWN21-17","DOIUrl":"https://doi.org/10.1898/NWN21-17","url":null,"abstract":"Abstract Grizzly Bears (Ursus arctos) are protected in the contiguous United States under the federal Endangered Species Act. The conservation strategy for the species encourages population connectivity between isolated Grizzly Bear Recovery Areas through Demographic Connectivity Areas. Another goal is reestablishment of a breeding population in the Bitterroot ecosystem through natural immigration. Using the locations of 362 verified Grizzly Bear den sites and Maxent as a resource selection function, we predicted 21,091 km2 of suitable denning habitats. Terrain features, distance to roads, and land cover best explained suitable denning habitats in northern Idaho and western Montana. The results support the demographic model for population connectivity, and independent of other factors there is suitable denning habitat for hundreds of Grizzly Bears in the Bitterroot analysis area. We suggest additions to the Bitterroot Grizzly Bear Recovery Area, and that more effective motorized-access management be applied to demographic connectivity areas.","PeriodicalId":142406,"journal":{"name":"Northwestern Naturalist","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116663975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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