Our latest scientific paper, published this week in the Journal of Wildlife Management, documents the resilience of Spotted Owls to fire in California. Fire is a natural process that western forests and the animals living there have adapted to over thousands of years. Fire is necessary to the dynamics of these ecosystems providing important habitat to many plants and animals and does not threaten sensitive populations such as California Spotted Owls.
Fire over the past decade has affected forests in the San Bernardino Mountains of southern California, providing an excellent opportunity to examine how this disturbance, and subsequent post-ﬁre salvage logging, inﬂuenced California spotted owl (Strix occidentalis occidentalis) breeding-season site occupancy dynamics there and in the nearby San Jacinto Mountains. Using occupancy survey data from 2003 to 2011, we estimated annual extinction and colonization probabilities at 71 burned and 97 unburned breeding-season sites before and after ﬁre, while controlling for confounding effects of non-ﬁre-related temporal variation and among-site differences in habitat characteristics. We found no statistically signiﬁcant effects of ﬁre on occupancy dynamics of spotted owls of southern California. However, we found some evidence that ﬁre and logging effects could be biologically meaningful. We documented a threshold-type relationship between extinction and colonization probabilities and the amount of forested habitat (conifer or hardwood tree cover types) that burned at high severity within a 203-ha core area around spotted owl nests and roost centroids. Sites where approximately 0–50 ha of forested habitat within the core area burned at high severity had extinction probabilities similar to unburned sites, but where more than approximately 50 ha of forested habitat burned severely, extinction probability increased approximately 0.003 for every additional hectare severely burned. The majority (75%) of sites burned below this threshold. Sites where high-severity ﬁre affected >50 ha of forested habitat could still support spotted owls, so all burned sites should be monitored for occupancy before management actions such as salvage logging are undertaken that could be detrimental to the subspecies. We also recommend that managers strive to reduce human-caused ignitions along the wildland–urban interface, particularly at lower elevations where owl sites are at higher risk of extinction from ﬁre.
LINK to Journal page for this article.
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