Author: Kurt Treftz, Cascade Pest Control

Secondary poisoning by second generation anticoagulant rodenticides (SGARs) to birds of prey and wildlife.

A Responsible Approach to Rodenticides—particularly SGARs—and Our Concern for Birds of Prey and Wildlife

We at Cascade Pest Control recognize raptors as beautiful and wondrous creatures of our local environment, and that they are perhaps most susceptible to secondary poisoning by certain rodenticides.

Introduction

There is growing evidence that certain rodenticides can cause “secondary poisoning” to non-target species, particularly birds of prey such as owls.

Cascade Pest Control has a long-standing reputation of environmental efforts and IPM (Integrated Pest Management) approaches to pest control. As a result, Cascade Pest Control is a leader in carefully selecting rodent control measures and the judicious use of rodenticides.

We at Cascade pest control love living in the greater Northwest region (Idaho, Oregon, Washington) and we have an awareness and affinity for our abundant wilderness and its wildlife. We also cannot help but appreciate our responsibility to balance protecting people, their homes, and their pets from rodent pests while avoiding impact on the greater environment. Cascade’s celebrated adoption of Integrated Pest Management (IPM) demonstrates the solution to these issues.

A Brief History & Context of Rodent Control & Rodenticides

Rodents—particularly rats and mice—have a long-standing history with humans, clearly resulting in the spread of disease and damage to our food and habitat. While the most infamous case of rodent-borne disease was the Black Plague long ago, there have been a few human deaths attributed to rodents (via Hantavirus) in the Greater Northwest Region as recent as 2017.

Rodents are a constant threat to food supplies from harvest, food production, shipping, storage, and distribution. Damage to homes, particularly insulation, and to electrical wiring, amounts to millions of dollars annually in the northwest states of Idaho, Oregon & Washington alone. Additionally, rats themselves threaten wildlife as they are an invasive species.

Rodent Control & Rodenticides

Prehistorical rodent control amounted to little more than people catching or clubbing rats and mice. The advent of domesticating dogs and cats helped early human settlements a good deal. Rodent traps were conceived over the centuries ever searching for a “better mousetrap.” Nevertheless, rodent damage and their spread of disease continued.

The earliest rodenticides contained arsenic and strychnine, both highly toxic and a risk to people, pets, livestock and wildlife. Believe it or not rodenticides containing strychnine for residential use were still available until 1989!

FGARs (First Generation Anticoagulant Rodenticides)

Anticoagulant rodenticides were first developed around 1950 to avoid the accidental poisoning of strychnine, arsenic and other toxic products. First-generation anticoagulant rodenticides (FGARs) were warfarin & diphacinone, which came with certain advantages and disadvantages:

FGAR Advantages: Lower toxicity, less rodent bait shyness, less risk to non-target animals and people (and antidotes are present for people and pets).

FGAR Disadvantages: Multiple feeding requirements were more labor intensive and not appropriate during initially addressing a rodent infestation which required rapid reductions of rats or mice. Rodents developed resistance to FGARs in some cases.

SGARs (Second Generation Anticoagulant Rodenticides)

With FGARs showing decreased effectiveness second generation anticoagulant rodenticides (SGARs) were developed from the late 1970s. Examples are bromadiolone and brodifacoum. Their improved effectiveness was celebrated in light of rodent damage and rodent-borne spread of disease, especially in urban and suburban areas, however there would prove to be downsides as well.

SGAR Advantages: Single-dose efficiency. Far more effective in controlling infestations.

SGAR Disadvantages: Presence in dying rodent can lead to secondary poisoning of non-target animals. Stricter regulations as a result.

Non-Anticoagulant Rodenticides

So the risks and benefits of rodenticides played out with additional research and the resulting development of non-anticoagulant rodenticides. Recent non-anticoagulant rodenticides include bromethalin and cholecalciferol. These products provide better alternatives when secondary poisoning is to be avoided.

Non-Anticoagulant Rodenticide Advantages: Low risk of secondary poisoning; Quick acting on rodents.

Non-Anticoagulant Rodenticide Disadvantages: Limited antidote makes them less suitable when pets are present.

Scientific Concern over Secondary Poisoning by SGARs on Non-Target Species (particularly raptors such as owls)

Recent studies demonstrate risks that second generation anticoagulant rodenticides can have on wildlife. The primary concern is over birds of prey as they may swoop to eat a dying rodent and their small size leaves them susceptible to smaller amounts of toxicants that may remain in a rodent.

This concern has prompted legislative efforts to change laws regarding the use of second generation anticoagulant rodenticides (SGARs), which has already happened in the state of California and elsewhere.

Dr Robert “Bobby” Corrigan, a PhD entomologist and “rodentologist,” is one of the few nationally-recognized leading experts in rodents. He understands both the threat rodents pose and also the very real problem regarding SGARs. In an article from Pest Management Professional Dr Corrigan recognizes “high-quality research” establishing (secondary poisoning as a rodenticide risk) and he said he believes these should become “restricted use pesticides” by the EPA and that routine use of SGARs in bait stations routinely, when not specifically warranted by present and acute rodent infestation is unprofessional.

Interestingly, he also made this point, “My ongoing experience is that the threat (of SGARs) to non-target (species) is mostly from two large aspects: rural (agricultural) applications and the lay public’s ready access to meant-for-professional SGARs from online purchases. The structural pest management industry, while the most visible and identifiable entity is, in my opinion, in third place after these two regarding posing risks to non-target(species.)”

The bottom line is that SGAR-rodenticides can pose a threat to wildlife—particularly to predatory birds. The key is to employ integrated pest management practices which utilize a number of control measures rather than solely utilizing rodenticides, and even then using the least invasive products. Utilizing IPM a balance is carefully weighed between environmental safety and safety from the treats rodents pose in terms of disease and structural damage. (more below)

Cascade and Our Responsible Approach to Rodent Control

Firstly, Cascade Pest Control earned a number of environmental awards since the 1980’s. Cascade is the only pest management company to have ever received an award by the EPA. In 1985 Cascade was recognized by EPA’s Region 10 in their Seattle headquarters. Cascade was also recognized by the Washington State Ecological Commission, and earned a Washington State Governor’s environmental award. We at Cascade Pest Control take seriously our responsibility to protect the wonderful northwest environment we love.

Secondly, Cascade has one of the highest numbers of personnel credentialed in Integrated Pest Management—a system that increases pest control while minimizing use of toxic products. Many of our personnel are Certified IPM Technicians and/or Associate Certified Entomologists as recognized by the Entomological Society of America.

Cascade’s IPM Approach to Rodent Control Minimizes Use of Rodenticides

Integrated Pest Management (IPM) addresses the whole picture rather than jump to usage of rodenticides alone. This approach minimizes reliance on rodenticides.

Inspection / Assessment – A careful and thorough inspection and assessment process is essential to understanding the scope and appropriate responses to any rodent infestation.

Exclusion – A step too easy skipped, exclusion is to make repairs and/or modifications to seal entry points where rodents easily gain access.

Sanitation and Education – No approach to pest management is complete without educating clients around various habits including sanitation. For example, excess pet food remaining in bowls or spills at a bird feeder attract and even nourish rats d mice. Client participation is critical for optimal IPM success.

Trapping – Traps, although more labor intensive, are an effective was to eliminate rodents without reliance on rodenticides.

Monitoring and Response – A crucial aspect of IPM is careful monitoring so as to know how, where and when to respond to rodent encroachment or infestation.

Rodenticide Selection and Use – Careful selection and use of rodenticides is called for, not the indiscriminate use of rodenticides that has occurred in the past.

Conclusion

The risks to us from infestations of rats or mice are not simply annoyances. They spread disease and they damage structures and automobiles. Plus, rodents are an invasive species directly affecting wildlife. At the same time, we at Cascade Pest Control recognize raptors as beautiful and wondrous creatures of our local environment, and that they could be most affected by secondary poisoning by certain rodenticides. As such Cascade is dedicated to a disciplined IPM approach to pest management to avoid harm to non-target animals.

Contact us today for more information or to schedule a service 888-989-8979.

Cascade’s Responsible Approach to Rodenticides