Habitat associations of cavity-nesting owls in the Sierra Nevada

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dc.contributor.advisor Morrison , Michael L . en_US
dc.contributor.committeeMember Wu , Xinyuan Ben en_US
dc.creator Groce , Julie Elizabeth en_US
dc.date.accessioned 2010 -01 -15T00 :11 :13Z
dc.date.accessioned 2014 -02 -19T19 :34 :17Z
dc.date.available 2010 -01 -15T00 :11 :13Z
dc.date.available 2014 -02 -19T19 :34 :17Z
dc.date.created 2008 -08 en_US
dc.date.issued 2009 -05 -15 en_US
dc.identifier.uri http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3086
dc.description.abstract Several species of small , cavity -nesting owls occur in the Sierra Nevada , including in areas impacted by human activities . The owls typically use standing dead trees (snags ) for nest sites . Although descriptive studies exist regarding habitats associations around nest and roost sites , few studies have examined habitat associations at larger spatial scales or relative to certain snag characteristics (e .g . , density , decay class ) . To improve our understanding of the habitat associations of these owls , I compared habitat characteristics at 2 spatial scales around areas of owl detection and non -detection . I also examined distances between conspecifics and heterospecifics to determine if clustering of conspecifics or avoidance of predators occurred . I conducted owl broadcast surveys and snag sampling during the spring and summer of 2006 and 2007 in the Lake Tahoe Basin of central Sierra Nevada . I measured additional habitat variables (e .g . , vegetation cover , distance to roadways ) from pre -existing geographical information system layers . I used stepwise logistic regression to ascertain which variables were influential in predicting owl occurrence . The northern saw -whet owl (Aegolius acadicus ) was the only species detected in sufficient numbers for statistical analysis , with a detection probability of 0 .25 . I detected saw -whets in a wide range of conditions and it appeared that few factors influenced their distribution in the basin . Areas dominated by white fir , however , were correlated with the absence of saw -whets at both the macrohabitat and microhabitat scales . White fir -dominated areas tend to occur on the west side of the basin and it is possible white fir was acting as a proxy for other factors not measured in this study , such as microclimate conditions or prey availability . I was also more likely to find a saw -whet within 1000 m of another saw -whet than within 1000 m of a non -use point , indicating clustering of conspecifics in the basin . While it appears saw -whet needs are being met in the basin , restoration projects are ongoing to decrease both the number of snags and relative abundance of white fir . Continued monitoring of the species is essential to understand potential effects of restoration activities . Suggestions are provided for appropriate timing and effort of future surveys . en_US
dc.format.medium electronic en_US
dc.format.mimetype application /pdf en_US
dc.language.iso en _US en_US
dc.subject owl en_US
dc.title Habitat associations of cavity -nesting owls in the Sierra Nevada en_US
dc.type Book en
dc.type.genre Electronic Thesis en_US
dc.type.material text en_US
dc.format.digitalOrigin born digital en_US


Habitat associations of cavity-nesting owls in the Sierra Nevada. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3086 .

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