urban naturalist
It Takes a Village Rat poison causes a slow, cruel death, and kills wildlife too. Better sanitation and upkeep of homes — easier said than done — controls rat populations effectively by bernard brown
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n march 19, 2019, Mom, the redtailed hawk matriarch of the Benjamin Franklin Parkway, disappeared. A post by Carolyn Sutton on the Franklin Hawkaholics Face� book page described how, over the previous weekend, Mom had been looking unwell, sitting listlessly on a branch and showing no interest in a dead rat delivered by her mate, T4 (“T” for tiercel, the word for a male hawk, and “4” because he was Mom’s fourth documented mate). In 2016, her previous mate, T3, had died of suspected rodenticide 10 GR ID P H I L LY.CO M JU LY 2 0 22
poisoning. Mom’s body was never recovered, but the hawkaholics suspected that she had suffered the same fate. The most commonly used rat poisons are slow-acting anticoagulants. The rats eat the bait but get sick gradually, eventually dying from internal bleeding. Older poisons like strychnine had the drawback of acting too quickly. Rats that saw others die soon after eating bait learned to avoid it. Anticoagulant poisons introduced in the mid-1900s killed more slowly but required rats to eat several doses to build up a lethal dose. The
“second-generation” anticoagulants now in use deliver a lethal but slow-acting dose in one feeding. One major downside of the slower death is that rats can wander out into the open after eating the bait, where they can fall prey to pets such as dogs or to wild animals such as hawks. The slow action of the poisons leaves the rats able to eat even after they have ingested a fatal dose. That high load of poison can then be ingested by rat predators or scavengers. Sutton draws a connection with the rats
I S TO C K P H OTO
A Cooper’s hawk dismembers a rat.
