Skip to Main Content
Site occupancy and reproductive dynamics of California spotted owls in a mixed-ownership landscapeAuthor(s): Brendan K. Hobart; Kevin N. Roberts; Brian P. Dotters; William J. Berigan; Sheila A. Whitmore; Martin G. Raphael; John J. Keane; R.J. Gutiérrez; M. Zachariah. Peery
Source: Forest Ecology and Management. 437: 188-200.
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
View PDF (6.0 MB)
DescriptionBiodiversity conservation in mixed-ownership landscapes often depends on contributions from privatelyowned lands, where natural resource development can alter and produce novel habitat conditions for species of conservation concern. A lack of research on private lands stemming from access issues and concerns over regulatory outcomes, however, often limits evaluation of the impact of land management. The California spotted owl (Strix occidentalis occidentalis), for example, often occurs in mixed-ownership landscapes but research on this species has occurred primarily on public lands. Therefore, we conducted the first large-scale private-public cooperative and comparative analyses of California spotted owls inhabiting mixed-ownership landscapes in the Sierra Nevada, California, USA. We surveyed 151 spotted owl sites from 2013 to 2017 within two study systems: one comprised primarily of public lands (national forests) where the owl population has declined over the last ∼20 years and a set of study areas comprised mostly of private lands on which relatively high estimates of site occupancy were recently reported. Multistate occupancy modeling indicated that the probability of occupancy and successful reproduction by owls depended on site status in the previous year, with both probabilities highest at sites where owls successfully reproduced in the previous year, intermediate at occupied sites where owls had not successfully reproduced, and lowest at previously unoccupied sites. Site occupancy probability was higher at low-elevation sites and lower at sites that contained more open area and younger forest. Successful reproduction by owls was also more likely at lowelevation sites and at sites with more north-facing slope and younger forest with high basal area of hardwoods. Study areas with more private lands tended to occur at lower elevations and have greater amounts of younger forest with high basal area of hardwoods, which may have contributed to higher occupancy and reproductive probabilities than the study area with more public land. Thus, differences in occupancy and reproductive probabilities between study areas appeared to be the result of differences in topographic and vegetation conditions that likely promote populations of key spotted owl prey species. Our results suggest that private lands in mixed-ownership landscapes may contribute to spotted owl conservation by conferring different benefits to owls than public lands and, more broadly, highlight the importance of including private lands in conservation research and planning.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationHobart, Brendan K.; Roberts, Kevin N.; Dotters, Brian P.; Berigan, William J.; Whitmore, Sheila A.; Raphael, Martin G.; Keane, John J.; Gutiérrez, R.J.; Peery, M. Zachariah. 2019. Site occupancy and reproductive dynamics of California spotted owls in a mixed-ownership landscape. Forest Ecology and Management. 437: 188-200. https://doi.org/10.1016/j.foreco.2019.01.028.
KeywordsCalifornia spotted owl, mixed-ownership landscapes, multistate, occupancy modeling, private land, public land, Sierra Nevada.
- Associations between forest fire and Mexican spotted owls
- Barred owl occupancy surveys within the range of the northern spotted owl
- The past and future roles of competition and habitat in the range‐wide occupancy dynamics of Northern Spotted Owls
XML: View XML