Earth Notes: Mexican Spotted Owls And Forest Fires

Sep 9, 2020

Mexican spotted owls are an iconic bird in the pine forests of the Southwest. They are also a threatened bird. On the Colorado Plateau, one of the most significant threats to owls are large, severe forest fires, which are becoming more frequent.

File photo: Mexican Spotted Owl

From 2014 to 2016 researchers from the School of Forestry at Northern Arizona University surveyed spotted owl populations across 46,000 acres affected by the Rodeo-Chediski Fire – where almost half a million acres were severely burned in 2002. Combining that information with U.S. Forest Service data, they’ve been able to compare owl breeding success pre- and post-fire, at burned and unburned sites.

Their findings show that - locally - severe wildfires may depress spotted owl populations for many years, because owls avoid nesting and roosting up to a quarter of a mile from areas where fire killed a third or more of the tree canopy. And, the owls prefer mature mixed conifer forest with large trees, a habitat often found in canyons, which are especially vulnerable to severe fire.

But on a larger landscape scale, it’s likely the owls can tolerate fire if there aren’t too many large, severely burned patches. Which is why forest thinning measures to decrease the risk and size of high severity fires are likely to help spotted owl populations, provided those activities don’t cause too much disturbance around roosting and nesting sites.

The U.S. Fish and Wildlife Service and U.S. Forest Service are involved in ongoing Mexican spotted owl surveys in forests being treated by mechanical thinning and prescribed burns to better understand how fire affects these charismatic birds.