Described as beautiful, aggressive and at once both soft and sharp, barred owls are an object of fascination and concern. Recent national news reports that barred owls are displacing spotted owls have the Sounder wondering just how the species fits into our island ecosystem, and did it force spotted owls from our isles?
Owl versus owl
According to the Cornell Lab of Ornithology in the Pacific Northwest barred owls are displacing and hybridizing with spotted owls – their slightly smaller, less aggressive cousins – which are already threatened from habitat loss.
That is why this year the U.S. Fish and Wildlife Service published an environmental impact statement explaining why it had approved the removal of about 3,600 barred owls from specific areas through Oregon, Washington and California.
According to Seattle-based nature writer Craig Welch, spotted owl populations in parts of Washington are half what they were in the 1980s.
“Throughout their range, from Canada to California, Northern spotted owls are disappearing three times faster than biologists had feared,” wrote Welch in his article “The Spotted Owl’s New Nemesis” in the Smithsonian Magazine.
Birds of a feather
Barred owls have vertical brown and light barring or streaking on the belly and lower chest, whereas the spotted owl has light spots on its chest. Both owls have dark brown, almost black eyes and their wings and tail are brown and white.
Barred owls live in large, mature forests made up of both deciduous trees and evergreens, often near water. They nest in tree cavities. In the Northwest, barred owls have moved into old-growth coniferous forests, where they compete with the threatened spotted owl. There is some data that suggests they are interbreeding, which is going to change the population, said Orcas biologist Kim Middleton.
In 1990, the Northern subspecies of spotted owl came under the Endangered Species Act (two subspecies in other parts of the country were not affected).
Both owls are not migratory birds, and generally stay in the same area. According to the Cornell Lab of Ornithology, of 158 birds that were banded and found later, none had moved farther than six miles away.
But what is interesting about the barred owl is that original populations were found in the East and during the 20th century the bird spread through the Pacific Northwest and southward into California.
Mark Lewis, the senior author of “Birding in the San Juan Islands,” said barred owls were first noted in the San Juan Islands in the early 1980s when they were considered “vagrants” but were actually the vanguard of a major colonization movement to the West Coast.
“They did not become established here until around 2000, a full decade later than Vancouver and Victoria [Canada] (they seemed to colonize parks and suburbs first),” he added.
According to the National Audubon Society’s Annual Christmas Count database, barred owls were not reported to be seen in the islands until 2007.
The mystery of the spotted owl
Local bird experts agree that spotted owls are not found here and there is little in the record books to suggest a significant population ever existed.
According to Lopez-based biologist Russel Barsh native people cleared and cultivated a large portion of the islands about 2,000 years ago. Barsh added that when the first wave of settlers arrived in the 1850s they burned the older coniferous forests that spotted owls would have chose for nesting.
Lewis agrees that when there were large area of virgin old-growth forests on the island it is likely that spotted owls dwelled and thrived here.
Middleton, who has lived on Orcas since 2006 and has participated each year in the Audubon Christmas Bird Count, concurs with Barsh and Lewis that spotted owls are closely linked to old growth.
“We do have old growth on the islands, but that section of forest on the island is small,” she said.
She also added that spotted owls rely heavily on flying squirrels for food.
More evidence to suggest the unlikely possibility of having a significant population of spotted owls is in the Audubon Christmas Count database where there are no statistics in the last 100 years to suggest that the species has lived on the islands.
According to the database, barred owls were not reported to be seen in the islands until 2007, meaning that it was almost impossible that the two species interacted, proving that barreds are not responsible for the lack of spotted owls in the San Juan Islands.
Barred owls
As barred owls are removed from the Pacific Northwest by wildlife officials in order to help boost the spotted owl population, should we be concerned over the barred owl moving in on animals indigenous to the island?
Middleton said that whenever you introduce a new predator to an ecosystem change will occur.
“When there are more predators the balance between predators may shift,” she said.
It is possible that the barred could kill and compete with smaller owls, Middleton added. Some islanders speculate that they have seen areas with barred owls where great horned owls used to live.
“I believe they are displacing great horned owls from former nesting sites, but that they will easily co-exist as they do in the Eastern U.S., said Lewis.
There is no data currently that can confirm these speculations.
In contrast to what may be happening on the island, according to the Cornell Lab of Ornithology in the Pacific Northwest the great horned owl is the most serious predatory threat to the barred owl.
She said when it comes to predators, their populations always fluctuate depending on food sources. According to the Audubon Christmas Count, two barred owls were reported in 2007 compared to the four counted last year.
As the rodent population increases, the barred owl population will rise, said Middleton and when the rabbit population rises so will great-horned owls.
These changes and the fact that the barred found its way across the rocky mountains to an entirely new habitat do not ruffle her feathers. She describes herself as a biologist that does not get wigged out by change.
“It’s way cool that people can see these predators. We’re getting to see evolution and migration changes in our lifetime,” said Middleton. “Nature is always moving and we are getting to see it.”
