By Ken Bevis, Stewardship Wildlife Biologist, Washington State Department of Natural Resources, ken.bevis@dnr.wa.gov
Round head, dark eyes, a big puffy owl looks down from mid canopy at curious humans. A loud call erupts, “Who Cooks for You. Who Cooks for You Alllllll.” Classic barred owl. I get an email from somewhere in lowland western Washington that reads, “I think we have a spotted owl on our property.” This has happened several times in the past 10 years. They look a lot alike.
Originally native to the forests of the eastern United States, barred owls (Strix varia) managed to cross the North American continent in the mid 20th century. It is thought this forest owl traversed the great plains by skipping from one forest patch to another (which did not exist in the distant past), including river bottoms, towns, and upland tree plantings. The first barred owl observation in Washington was in 1965, according to the U.S. Fish and Wildlife Service.
Barred owls are now commonly observed on forestlands in Washington. They live in a wide variety of habitats, including younger forests. They eat almost anything that moves and were called “flying coyotes” by wildlife biologist Dr. Peter Singleton in a memorable talk about barred owl diets.
In the WSU podcast, the Forest Overstory, Dr. Jerry Franklin, the de facto dean of Northwest forestry, posited that the ecological impact of this highly adapted and successful new predator on local fauna could be substantial. Barred owls, the ecological newcomer to our forests, are a big deal for multiple reasons, including their relationship to their closely related cousin, the spotted owl.
Note the spotting on the breast, light on dark. (Photo: William Meyer)
Northern spotted owls (Strix occidentalis caurina) are creatures of deep, mature forests, specializing in mid-sized, nocturnal, arboreal mammals, primarily the northern flying squirrel (Glaucomys sabrinus). Flying squirrels den in cavities in large trees, especially large hollow snags and eat mushrooms that they find. The primeval dance of the spotted owl and flying squirrel once occurred in all low and mid-elevation, fir-dominated forests of the Pacific Northwest (another sub-species of spotted owl lives in forest pockets in the Southwest). In this deep forest, uncommon goshawks were primary predators on spotted owls, working the proverbial day shift. Great horned owls, another avian predator, live along forest edges and in more open habitats so they generally didn’t threaten spotted owls.
Rarely would a mammal – such as a marten or fisher – have a chance at the arboreal owl, either. Predation was limited, they live a long time and don’t migrate far from dedicated territories. Hence, spotted owls evolved into the tame and mellow creatures I encountered as a spotted owl biologist. Sometimes while handling them, they would completely relax in our hands.
I admire barred owls – a species beautiful in appearance and adaptable in nature. They are scrappy critters that thrive in amazingly variable circumstances by being aggressive and opportunistic hunters. They have smaller home ranges than spotted owls and produce more young. Barred owls dine on a wide variety of prey, including insects, worms, squirrels (day and night), wood rats, rabbits, deer mice, snakes, salamanders, and even fish.
I found a remarkable 2023 paper wherein Ryan Baumbusch analyzed stomach contents and body condition of over 1,300 barred owls that had been lethally removed in the pilot barred owl removal projects over the past few years. Here are a few pithy quotes from the paper to bear out the differences between spotted and barred owl diets:
“Diet composition of barred owls differed substantially from that of northern spotted owls in that prey species that typically comprise the majority (>50%) of spotted owl diets (e.g., flying squirrels (Glaucomys spp.), woodrats (Neotoma spp.), and tree voles (Arborimus spp.) comprised <10% of barred owl diets in WA and <3% of diets in OR. ….
Ryan Baumbusch – “Foraging ecology of barred owls where they are outcompeting the threatened northern spotted owl”
Mammalian insectivores – shrews (Sorex spp.), shrew moles (Neurotrichus gibbsii), and moles (Scapanus spp.) – along with salamanders were consumed at a high frequency by barred owls, suggesting these taxa may be at risk from invasive predator at high density. These prey, as well as arthropods (insects), contribute little biomass to the diets of northern spotted owls, yet contributed 12-51% of the dietary biomass of barred owls in my study…..
The barred owl’s broad diet and generalist habitat use has likely allowed this invasive species to expand throughout the range of the northern spotted owl and outcompete the threatened congeneric. While the threats posed by barred owls are pressing and complex, these threats are likely not limited to northern spotted owls alone, as a variety of prey species may also be at risk from this new predator in the forests of the Pacific Northwest.”
Barred owls are here to stay and are also developing relationships with people. In 2020, I wrote an article about barred owls and their exciting habit of swooping on people out minding their own business.
Spotted owl populations were well studied and monitored over several recent decades, especially around the time the controversy erupted, and the federal government listed them as a threatened species. This meant that (for a while), crews of biologists and technicians, aka “hooters,” went out on prescribed routes, emitting spotted owl calls and locating territorial spotted owls. Follow up work in daytime forests would locate nest sites by finding roosting owls and offering them live mice. When the owl swooped to take the mice, the workers (like me) would follow and chase the owl as it flew through the forest canopy, listening closely for the transfer call sequence between the female, on the nest with eggs or owlets, and the male who usually took the bait. The ultimate success of this work was finding the nest tree, usually a dwarf mistletoe clump (in eastern WA), a big, hollow broken top tree, a pileated woodpecker cavity, or other type of platform in the dense forest canopy.
In late May and June, we would go back to the same nest groves and hopefully find fuzzy juveniles perching on branches. They often acted charmingly dumb, spinning their cute faces as we squeaked. The parents would sit close by the young ones, watching us intently, but not attacking even if we grabbed the juveniles off the branches to band them. I did this work, including catching, banding and radio marking spotted owls over eight years. This is how my career as a wildlife biologist began.
Known and discovered spotted owl nesting territories were mapped and sometimes used to designate either protected habitats, or as filters for timber harvest planning. In my work, we found the birds, put dots on the paper map, handed it off and went back out to the woods. It was interesting and fun.
When out looking for and monitoring spotted owls in the late ’80s and mid ’90s on the east slopes of the Cascades, it was unusual to encounter a barred owl. In fact, our crews would take note and be surprised when we found them. Today, in those same areas, spotted owls are rare. It is thought they have been outcompeted and overwhelmed by the barred owl. It is an interesting fluke of history that there was substantial work being done with these forest owls across the entire region as the barred owl populations grew.
I reached out to my friend and former colleague, Margy Taylor. She worked on the long-term owl monitoring project in and around Cle Elum, Washington, and knows first-hand about the population shift from spotted to barred owls. She responded via email and I quote her directly:
“From the time I began doing field work studying spotted owls in 1987 to when I retired in 2014, I was able to witness, first-hand, the crash of the population of spotted owls on the east slopes of the Central Washington Cascades. In the early 1990s we were monitoring well over 100 occupied spotted owl territories, and by the time I retired in 2014, the territories occupied by spotted owls had fallen to less than 10. Some of the territories were simply vacant. Others had been taken over by barred owls. We were once able to monitor a territory where a spotted owl was paired with a barred owl. The pair raised young that fledged and we verified the fledged hybrids as adults in subsequent years. The combination of loss of habitat and climate change has made life for spotted owls nearly impossible here where I live. Barred owls, with their more varied diet are much better able to make do in the compromised habitat available now.”
The controversy around spotted owls began when biological studies strongly indicated this bird’s habitat need for older forests. Forest Service harvest quotas at the time were leading to owl population problems and timber policies were changed. Adjustments in harvest levels, and listing as a federally threatened species in 1990, forced substantial modifications to planned forest management over a very short time frame. This resulted in economic displacement, and controversy. The “owl wars” are still a source of bad feelings in our region.
Fast forward: Habitat conservation on a large scale has apparently not been enough to save the spotted owl from rapid population declines. The U.S. Fish and Wildlife Service introduced a proposal for direct action to control barred owl populations through removal (i.e. killing). The introduction to this document gives another good overview of the biology of the situation, and rationale for this proposal. Here is a good summary of the relationship between spotted and barred owls on a National Park Service publication.
Would removing barred owls in spotted owl habitats improve the likelihood of northern spotted owl survival? Possibly. But the program would have to continue indefinitely, as the supremely well adapted barred owl has successfully permeated mid to low elevation forests across the Pacific Northwest. Funding levels for wildlife programs have always been variable, and it would be a long-term commitment.
Would this proposal have an impact on small forest landowners? Seems unlikely, as the core protected habitats of the spotted owls are on federal and some industrial lands. Conservation strategies around habitat protections (federal management and DNR implemented Spotted Owl Special Emphasis Areas) would likely stay in place (my opinion).
Many people object to the idea of direct intervention of any kind on wildlife populations, advocating for more passive approaches, where we let nature take its course. But, what if the situation in question is not “natural” and due to human activities? Some contemporary examples: Sea lions eat endangered spring chinook at Bonneville dam. Starlings compete with Lewis’ woodpeckers or bluebirds for nest cavities. Wolves are considered unwanted predators on elk in Idaho and Montana. Skunks live under someone’s chicken house. Where is the line for appropriate active management on wild populations?
If we are lucky, each of us has a moment in our lives, where we touch history. Mine was the chance to work with this remarkable bird, the Northern spotted owl. “Spotty” changed the course of my career, and my life.
Works Cited
Baumbusch, Ryan. 2023. Foraging ecology of barred owls where they are outcompeting the threatened northern spotted owl. Oregon State University, Phd Thesis. https://ir.library.oregonstate.edu/concern/parent/6395wg81m/file_sets/gb19ff47b
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