Northern Spotted Owl Found on Mt. Tabor Died Due to Rodent Poison 

By Stephanie Herman, Assistant Conservation Director-Wildlife Care Center Manager

On Monday, November 6, a distressed Northern Spotted Owl was discovered on the ground at Mt Tabor Park in SE Portland. Northern Spotted Owls are listed as threatened under Oregon State and the federal Endangered Species Act, and are rarely seen in developed areas. A Bird Alliance of Oregon employee rescued the bird and brought them to our Wildlife Care Center for treatment. Despite the best efforts of our trained wildlife medical professionals, the bird passed away overnight. We now know, after testing performed by the Oregon Department of Fish and Wildlife, that this bird was suffering from secondary rodenticide poisoning. 

Northern Spotted Owl found on the dirt pathway at Mt. Tabor Park
Northern Spotted Owl found at Mt. Tabor Park, photo by Tara Lemezis

Rodenticide poisoning is a common threat to many predatory animals, especially owls and other raptors, as they can ingest the toxin by eating poisoned rodents, or poisoned rodent carcasses. In addition, although rodenticides and rodenticide bait stations are often billed as only attracting their target mouse and rat species, other animals including pets, other small mammals, and omnivorous species like raccoons can also directly consume the poison. Wildlife can become sick or even die from a single exposure to rodenticide, but can also suffer chronic, low-dose exposure that leads to death over time. In this case, rodenticide was tragically responsible for the death of an imperiled species whose numbers continue to decline in Oregon.

There are many types of rodenticide on the market, both over-the-counter and only via licensed, commercial pest management companies, and while some are marketed as safer alternatives, none kill immediately and thus poisoned rodents can travel from the point of exposure and enter the wild food chain. Most rodenticides work over days, but even the fastest acting poisons work over hours, not minutes. Depending on the type, the effects of rodenticides vary widely and include excessive bleeding, respiratory failure, and other organ failure, and are not particularly humane even on the target species.

We don’t know where or when this bird was exposed to rodenticides, but the reality is that wide and unsafe use of these products puts wildlife at risk across the state. Residents, businesses, and government agencies can all do their part to reduce wildlife deaths by using alternative methods to manage rodent populations. If more people had acted, the Northern Spotted Owl might still be alive today.

Rodenticides are billed as an easy solution to rodent infestations, however the isolated use of rodenticide only temporarily reduces local rodent populations. Controlling rodent infestations long-term requires identifying and removing the access to or presence of attractants such as food, bedding, and safe hiding places that are supporting the rodent colony to begin with. Without addressing these things, some rodents will die, but the remainder of the rodent colony will continue to reproduce and other rodents will move into the area, drawn by available resources. And, while in some cases it may be necessary to decrease the population of a rodent colony through lethal means in conjunction with other control measures, snap and electric traps are a more humane option with fewer risks to non-target species and the ecosystem as a whole. Never use glue or sticky traps, as these are extremely inhumane and dangerous to non-target species.

Many were curious why a Northern Spotted Owl would be found so far outside of its normal range. While we can’t know how the owl ended up in Mt. Tabor Park, it’s possible that this hatch-year bird dispersed in the wrong direction. The species relies on old growth forest, and less than 10% of Oregon’s old growth forest remains.