Driving Route 1 between Camden and Portland has always been one of my quiet pleasures. For decades, those trips were punctuated by the silhouettes of red‑tailed hawks, hunched and alert on roadside trees. On a typical drive I would count three to six hawks without trying very hard. In the past few years, that has changed. Now I may see a single red‑tail every three or four trips south. Among my rural neighbors, the chorus of barred owls that once called regularly has thinned, as well.

Those are anecdotal observations, and as a scientist I am cautious about reading too much into any one person’s field observations. But what is not anecdotal is the growing body of hard data showing that predatory birds and mammals across our region—and across North America and beyond—are carrying an increasing toxic load of rodenticides. Pesticide use remains widespread, and the evidence increasingly links it to wildlife declines. This week I had the opportunity to present both oral and written testimony to the Maine Board of Pesticides Control, and that experience left me convinced that we need to rethink rodent control from the ground up.

I am a resident of Camden, a Certified Senior Ecologist through the Ecological Society of America, and I hold a doctorate in wildlife ecology. I’ve spent my career working at the intersection of human activity and wildlife conservation. When I started digging into the State’s own rodenticide report, and the recent science it cites, I came away with a stark conclusion: slow‑acting anticoagulant rodenticides have no place in Maine’s outdoor environments — whether in the hands of homeowners or professionals.

Anticoagulant rodenticides are designed to be attractive, slow‑acting poisons. They cause internal bleeding over days, not minutes. That delay means rodents continue to move and feed after eating the bait. From a product‑design standpoint, the slow action is intended to prevent “bait shyness.” From an ecological standpoint, it’s a disaster. Because these compounds are fat-soluble and can persist for months in the liver, poisoned rodents often become impaired before they die, making them easy prey for hawks, owls, foxes, fishers, bobcats, and other scavengers and predators. In so doing, the poisons concentrate up the food chain ironically killing the very species whose job it is to control rodents. 

State and regional data now show just how pervasive that contamination has become. Studies in New England have found that nearly all sampled red‑tailed hawks—96 to 100 percent—carry residues of one or more anticoagulant rodenticides, often several different compounds in the same bird. Similar surveys of fishers show more than half of Maine animals tested positive, with even higher rates in neighboring states. Sampling by Maine’s Department of Inland Fisheries and Wildlife detected rodenticides in every bear they tested and in most of the hawks. Nationally, large studies of eagles and other raptors are showing exposure rates routinely above 80 percent.

At the same time, a different set of studies has highlighted a larger pattern that should be especially sobering to a coastal community like ours.

A new analysis published in the journal Science this February mapped “acceleration hotspots” of bird declines across North America. The authors found that the places where bird losses are speeding up fastest are strongly associated with intensive agricultural activity — specifically, in areas where pesticides are in use. In these hotspots, heavy pesticide and fertilizer use emerged as a dominant predictor of accelerating declines. Comparable work in Europe has reached similar conclusions: modern farming practices, and particularly pesticide use, are now primary drivers of farmland bird declines.

Taken together, the rodenticide data and these large‑scale bird studies paint a consistent picture. Across landscapes already stressed by climate and habitat change, we are adding additional, avoidable toxic pressure through the widespread use of rodenticides.

For predators like hawks and owls and fishers that sit at the top of food chains, rodenticides are especially insidious.

There is another problem with our reliance on rodenticides: they do very little to address the root causes of rodent infestations. Rodent populations are driven overwhelmingly by food, shelter, and access to buildings. During the COVID‑19 lockdowns, when restaurant and food‑service waste briefly plummeted, rat activity predictably declined—even though rodenticide policies did not change. When food waste and access returned, so did the rats. Similar studies in several U.S. cities show the same dynamic: poisons produce limited declines in rodent numbers, and rat populations rebound quickly unless food availability and access is addressed. 

Rodenticides do not work when the underlying problems—food waste, leaky trash and open entry points—are unaddressed. Meanwhile, repeated doses of poison select for resistant rodents and progressively contaminate the predators we rely upon to provide natural control.

Please avoid purchasing and applying anticoagulant rodenticides, especially outdoors.

For indoor infestations, prioritize Integrated Pest Management (IPM) and mechanical control first; consider professional, tightly controlled indoor use only as a last resort. IPM starts with exclusion—sealing cracks and gaps in foundations, installing door sweeps and placing screening over any vents.

Next, address sanitation and waste management: secure trash, avoid permanent outdoor pet feeding, manage bird feeders so the seed doesn’t spill on to the ground.

Instead of rodenticides, use mechanical methods like snap traps, multi‑catch traps Havahart-style traps.  If you use live traps, follow Maine wildlife guidance and local rules for humane handling; in many cases relocation is discouraged.

The most durable solution is still exclusion + sanitation. Electric traps that kill quickly and do not introduce persistent toxins into the environment are also good options. IPM has repeatedly been shown to reduce pesticide use by 90 percent, much better result than any rodenticide use.

At the hearing, the Board proposed a prudent intermediate step: classifying the most potent second‑generation anticoagulants as “restricted use,” available only to licensed applicators. That is an important recognition that these compounds pose disproportionate risk and should not be on hardware‑store shelves. But the science—and, frankly, common sense—suggests we should go further.

First‑generation anticoagulants also accumulate in predators. No amount of training can stop a poisoned rat from leaving a bait station and dying in a hedgerow, where an owl or hawk or bald eagle can eat it. As long as we are relying on slow‑acting poisons outdoors, we are guaranteeing a steady leak of toxins into the food web.  It really is that simple.

For that reason, my written testimony to the Board argues for a complete phase‑out of anticoagulant rodenticides for outdoor use in Maine, including professional applications, coupled with strong support for IPM and preservation of tightly controlled indoor structural use as a true last resort.

That means focusing our collective effort on exclusion, sanitation, mechanical control, and, where appropriate, newer non‑lethal tools like fertility control. It also means investing in education so that landlords, municipalities, and homeowners know how to do IPM well—and are not left thinking poison is the only answer.

As neighbors along the Midcoast, we have to decide what kind of landscape we want to inhabit. One in which rodent problems are managed naturally and ecologically, with hawks and owls doing their quiet work along our fields and roadsides? Or one in which persistent poisons amplify up the food chain, and killing the wildlife that are sentinels of a healthy ecosystem?

When I drive Route 1 now and see fewer red‑tailed hawks or when March nights arrive with fewer barred owls hooting in the woods, I am reminded that widespread rodenticide exposure in predators is very likely contributing to wildlife declines.

The choices we make in Maine over the next few years—about rodenticides, about IPM, about how seriously we take the emerging science—will determine whether hawks and owls remain a familiar part of our sojourns and our nights, or just things we remember seeing more of when we were younger.

Please consider signing Maine Audubon’s Petition “Reducing Rodenticides In Maine” no later than March 8 when the petition closes: https://maineaudubon.org/news/reducing-rodenticides-in-maine/ and volunteering with our new group, Rodenticide-Free Maine Coalition by emailing: jacquie.gage@gmail.com

If you want more information on the underlying science covered in this article, write to me here: podolsky@att.net