California Spotted Owls Benefit From Forest Restoration

Forest restoration can help California spotted owls that typically depend on old-growth forests, new research finds.

Years of heavy logging, droughts, and fires have transformed forests in western North America. Instead of large, old trees with high canopy cover, they are now filled with smaller, newer growth. Scientists were worried that restoration efforts would harm the spotted owls that relied on this habitat.

“Forest restoration often involves some removal of live trees—mostly small and medium-sized trees in the forest understory that have grown in because of fire exclusion. These smaller trees increase fire risk to owl habitat, and removal of these smaller trees will protect the rare, larger trees that owls use for nesting,” lead author Gavin Jones, Ph.D., a research ecologist with the USDA Forest Service (USFS) Rocky Mountain Research Station, tells Treehugger.

“Yet there is a long-standing belief that removal of any trees (of any size) in spotted owl habitat will be detrimental to the owl, and therefore should not be done—it is this perspective that leads to the conclusion that forest restoration activities cannot be done in owl habitat and is antithetical to the conservation of the owl. Our work, and that of others, has shown this dichotomy is overly simplistic.”

About Spotted Owls

Spotted owls have been the subject of several conservation and protection battles. Spotted owls are classified as near threatened by the International Union for the Conservation of Nature (IUCN) with their numbers decreasing.

The Northern spotted owl (Strix occidentalis caurina) and Mexican spotted owl (Strix occidentalis lucida) are listed as endangered under the federal Endangered Species Act. Efforts to protect those owls met with resistance, as the interests of loggers clashed with the goals to protect old-growth forests.

Their cousin, the California spotted owl (Strix occidentalis occidentalis), has not earned endangered status on the ESA.

California spotted owls typically live in older forests that have the habitat needed for nesting and foraging. Their nests are generally made in areas with high canopy cover, old, abandoned trees, or in large trees. They rotate through foraging sites and prey on a variety of species including woodrats, flying squirrels, birds, and insects.

Modeling Fire and Owls

For their study, researchers developed a simulation with two elements: a fire model and an owl model. They predicted future severe fires across the Sierra Nevada through the mid-century.

“Both were statistical models developed using decades of data to ensure they would perform realistically,” Jones explains.

They linked the models together and simulated them into the future under climate change and forest restoration scenarios.

“When simulated fires occurred in the fire model, they fed into the owl model and influenced the owl population,” Jones says. “This type of interdisciplinary work is rare—this was a collaboration between applied climatologists, fire modelers, and wildlife ecologists. The resulting simulation model is quite unique in that way and produced an incredibly useful result.”

They found that the amount of severe fire predicted changed with a reduction in simulated fuels and forest restoration treatments. Owls responded to the potential effects of those treatments on their habitat.

“We found the direct, and potential negative effects of forest restoration to owl habitat (that is, removal of trees in owl habitat) were small relative to the positive effects that restoration had on reducing fire risk to owls,” Jones says. “So even though in some cases we found that restoration could have negative short-term impacts to owls, it reduced the long-term impacts of severe fire. These long-term benefits led to better outcomes for owls.”

In some scenarios, the findings suggest that placing restoration treatments inside owl habitats would cut the predicted amount of severe fire almost in half compared to treating the same area outside of their territories.

“In essence, placing treatments inside of owl territories had an outsized effect on reducing future severe fire in the Sierra Nevada bioregion,” Jones says.

“This leads to some important conclusions. First, if one goal of management is to reduce future stand-replacing wildfire, then placing treatments in owl habitat will help achieve that goal. Second, if treatments are done in owl habitat—yet avoid removal of large, old trees—treatments are likely to lead to much larger benefits to owls, too.”

The results were published in the journal Frontiers in Ecology and the Environment.

The researchers are now looking beyond the spotted owl to see how other forest wildlife might respond to fires and forest management.

“We think these findings have the potential to be transformative as managers attempt to increase the pace and scale of forest restoration activities in dry forest ecosystems,” Jones says.

“The idea that spotted owl conservation and forest restoration are ‘in conflict’ is an overly simplistic, and now outdated notion. Our work suggests not only that forest restoration may provide co-benefits to owls, but actually that the two goals (forest restoration and owl conservation) may be codependent.”

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