Frequent, heterogenous fire supports a forest owl assemblage.

Area of Science:

• Ecology
• Forestry
• Wildlife Conservation

Background:

• Fire is a natural disturbance in many forest ecosystems, influencing biodiversity.
• Altered fire regimes, driven by climate change and historical management, result in larger, more severe fires.
• The ecological impact of changing fire severity and frequency on forest owl species and assemblages remains poorly understood.

Purpose of the Study:

• To investigate the effects of fire severity, history, and spatial configuration on a forest owl assemblage in the Sierra Nevada.
• To determine the short-term and long-term impacts of different fire severities on various owl species.
• To assess the adaptability of forest owls to historical fire regimes versus novel "megafire" conditions.

Main Methods:

• Utilized ecosystem-scale passive acoustic monitoring over 35 years in the Sierra Nevada, California.
• Analyzed the impact of fire severity, history, and configuration on six forest owl species.
• Compared species responses to low-, moderate-, and high-severity fire events.

Main Results:

• Negative impacts of fire on the owl assemblage were generally ephemeral, lasting 1-4 years.
• Spotted owls exhibited avoidance of high-severity burn sites for up to two decades.
• Low- to moderate-severity fires positively influenced small cavity-nesting species and great horned owls.

Conclusions:

• Most forest owl species are adapted to historical fire regimes characterized by a mosaic of low- to moderate-severity fires.
• Novel "megafires" (larger, more frequent, and contiguously severe) pose a significant threat by reducing suitable habitat and altering fire-severity distributions.
• Conservation strategies should focus on restoring historical fire patterns, promoting a mosaic of forest conditions, and managing for low- to moderate-severity fires to support owl assemblages.