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Cottonwood Heights Journal

You Dirty Rat

Apr 09, 2018 11:11AM ● By Aspen Perry

Two great-horned owl babies, treated at Wildlife Rehabilitation Center of Northern Utah (WRCNU). (WRCNU)

For anyone who has resided in Holladay for some time, it is no secret the city has no shortage of rodents that enjoy lurking near the many creeks and streams throughout the city.

 What may be less prevalent in the minds of residents is how attempts to kill rats and mice could be negatively affecting the urban wildlife population they come in contact with, such as owls.   

“This is an issue that needs to be brought to the attention of citizens,” said Heather Dove, president of the Great Salt Lake Audubon, in a recent email sent to City Journals staff to alert all unaware of the unintended consequences of rodenticides.

 Dove said many residents would welcome the knowledge of the potential trade-offs when using rodent poison.

 In November 2017 and January 2018, the Great Salt Lake Audubon received two resident reports of owls found either already dead or unresponsive with no apparent signs of foul play.

 In the November case, the great horned owl, found in Big Cottonwood Regional Park, was taken to the Wildlife Rehabilitation Center of Northern Utah (WRCNU). The WRCNU noted the owl’s internal bleeding was likely due to the owl ingesting rodenticide.

 During a mid-March phone interview, Neil Paprocki, conservational biologist with, cautioned against the assumption that all owl deaths were due to poisoning. 

 “It’s certainly a concern, but there is still of lot of research that needs to take place,” Paprocki said.

 Paprocki said one hurdle in acquiring better data is the cost of testing, which can range between $100–150 for each bird tested. A cost DaLyn Erickson-Marthaler, executive director of WRCNU, clarified could go up to $300 if further testing was needed.

 For WRCNU — a nonprofit that takes in roughly 2,500 wildlife animals a year — the cost of testing means less funds for life-saving medical attention.

 “We can’t afford to test all of them, because there is no state or public funding. We want to focus our funds into the medical cost of saving them,” Erickson-Marthaler said.

 Despite rehab centers being unable to test, both Paprocki and Erickson-Marthaler noted WRCNU is able to look for signs of poisoning, such as internal bleeding — as noted in the November case of the great horned owl found in Cottonwood Regional Park.

 “The Wildlife Rehabilitation Center of Northern Utah is the best and closest center for people to go to,” Paprocki said.

 In accordance with, second-generation anticoagulants rodenticides (SGARs) are particularly harmful and at the root of suspicion regarding the death of predatory birds.

 As Paprocki explained, the SGARs do not kill rodents right away, which allows rodents to transfer the poison to other rodents.

 “But that also becomes problematic to the predator animals,” Paprocki said.

 The potential threat to non-targeted mammals due to rodenticide is being studied throughout the nation, as well as in Canada.

 In July 2014, California’s Department of Pesticide Regulation adopted a regulation to restrict the purchase of rodenticides containing the active ingredients commonly found in SGARs due to “overwhelming evidence of wildlife weakened or killed by SGARs.”

 Erickson-Marthaler expressed her concern regarding poisoning as a form of rodent control. “(When unintentionally) killing owls that are eating the rodents, you’re shooting yourself in the foot.”

 In addition, Erickson-Marthaler explained the devastation to the future owl population, since babies eat three times more than adult owls do.

 “The barn owl, for instance, grow incredibly fast — they have to eat about three to four times the amount of the adults,” Erickson-Marthaler said.

 In lieu of poisons, which can harm not only owls but other non-target animals, Erickson-Marthaler recommended removing the food source to rodents as a preventative measure in addition to removing toxins, and creating an owl box for safe sanctuary.

 For more information, Dove recommends citizens visit to help keep non-target animals safe.