Owl Decline Due to Multiple Factors

Once a thriving population, Northern spotted owl populations are now declining. ScienceDaily, a well-known online science  magazine, published an article covering this topic, Northern Spotted Owl Decline Linked to Invasive Owl, Habitat Loss, and Climate. This article covers the reasons why Northern spotted owl populations are on the decline as well as some history behind the population. The first reason listed is because of invasive owls. This, according to researchers, is “a pivotal role in the continued decline of spotted owls.” The main invasive owl, the barred owl, fight the spotted owls for food, habitats, and space. Since the Northern spotted owl has been started to be monitored in Washington, Oregon, and California, researchers have discovered that populations “declined 55-77 percent in Washington, 31-68 percent in Oregon and 32-55 percent in California.” This shows that invasive owls, such as the barred owl, alone have a huge impact on spotted owl populations. According to Dr. Katie Dugger, a research biologist at the USGS Oregon Cooperative Fish and Wildlife Research Unit at Oregon State University as well as one of the leaders on the report, she stated that the study “provides strong evidence that barred owls are negatively affecting spotted owl populations.” When, however, barred owl removals began in California in 2009, spotted owl populations as well as survival rates “increased on the latter area since the removal of barred owls started” showing that the spotted owl is unable to handle an influx of barred owls. She also goes on to tell about the importance of suitable habitats for the owls. The owls need these habitats to nest and roost. These are important “because spotted owl survival, colonization of empty territories, and number of young produced tends to be higher in areas with larger amounts of suitable habitat.” The preference of habitat for the spotted owl, old-growth forest, seems to be on the decline, unfortunately. According to the U.S. Fish and Wildlife Service, the spotted owl was listed as ‘threatened’ in 1990 due to the “declines in old-growth forest habitat throughout its range in Washington, Oregon and northern California.” Hopefully, after many of the barred owls are removed, these owls will once again be able to thrive. I do wonder, however, how the barred owl impacts the spotted owl? If the barred owl is responsible for most of the spotted owl population decline, then why does the article not cite how the barred owl is impacting the spotted owl? I can only hope, however, that the removal of barred owls, along with the continued protection of  old-growth forests continued so that this species is not lost to time completely.


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