Since the 1970s, California Spotted Owls (Strix occidentalis occidentalis [CSO]) have been documented on private forest lands currently owned by Sierra Pacific Industries (SPI) in the Sierra Nevada of California. In 2012, SPI began an occupancy study on a portion of the CSO population known to occur on or near its managed forests in 5 watershed study areas averaging 110 km2 each. These watersheds occur from the southern end of the Cascade Range to just north of Yosemite National Park. We concluded that 57 historical CSO sites existed in these areas at the beginning of the study. During 2012 through 2016, the survey effort increased the total number of known CSO sites in the study areas to 65. During the same period, the yearly occupancy of the CSO sites within the study areas ranged from 70 to 86%, with 98% of the sites occupied during at least 1 y. Crude densities during the study period were calculated to be 0.117 CSO-occupied sites km−2. Compared to other studies in the Sierra Nevada, the CSO populations on our 5-yr study areas showed relatively high occupancy rates and a wide range of crude densities.
New report authored by SPI Senior Wildlife Biologist, Kevin Roberts. ACCG does not have access to the full text version of this article. Check with Jay Francis to see if he can get you a copy.
Here’s something worth watching: a great video on the SPI site showing Kevin doing some GREAT owl calls. Really… watch this! Link: http://www.spi-ind.com/OurForests/WildlifeAndPlantSpecies