Choose Your Poison...Wisely!

Most people gaze a hawks and owls with a sense of awe – mice and rats, not so much. What you may not know is that rodents represent an important food source for wildlife, including birds of prey.

While many of us prefer to eradicate rodents when they share our living space, it is important to realize that the method we employ to remove these pests from our home environment can have a devastating effect on the pets we love so dearly, and on the birds of prey we find so mesmerizing. 

There are many different names for rodenticides available on the market, and although the use of several very toxic chemicals are restricted and considered a danger to the public, several of these products can still be found on store shelves and continue to be the poison of choice for some pest control entities as a successful method for rodent removal.

How Do Rodenticides Work And Why Do They Affect Birds Of Prey?

Anticoagulant rodenticides are used to control rodent populations. These poisons interfere with blood clotting, causing the rodent to bleed out internally, resulting in death. This is referred to as primary exposure. What you may not know is that as the rodent becomes sicker due to the effects of the poison, it also becomes slower and much easier to catch by birds of prey (hawks and owls), other mammals (foxes and raccoons) and our pets (dogs and cats). These animals ingest the poisoned rodents and begin to experience similar effects from the poison. This is referred to as secondary exposure.

Brodifacoum is the second-generation anticoagulant rodenticide found in many of the birds of prey necropsied in the Tufts Cummings School of Veterinary Medicine Study conducted by Clinical Assistant Professor Maureen Murray. Maureen presented at the Connecticut Wildlife Rehabilitators Association (CWRA) meeting last fall and her findings were very depressing to everyone who appreciates wildlife. The photographs we viewed illustrated the truly devastating effects of Brodifacoum – and you should know that this poison in particular presents a high secondary risk to birds of prey AND mammals. To learn more about various poisons, including Difethialone, Bromadiolone, Chlorophacinone, and Diphacinone and the effect they have on you and our ecosystem, visit the National Pesticide Information Center (NPIC).

What Happens To The Affected Birds Of Prey?

The affected birds of prey will often meet an untimely end, due to internal bleeding. Birds are often found lethargic with large areas of bruising but without an apparent injury or fracture to induce bleeding. To the untrained eye, the cause of the problem may not be diagnosed quickly enough to save the affected animals. If detected in time, the birds can receive treatment and are given the antidote, Vitamin K 1. However, even if treated successfully, many of these birds will continue to ingest these poisons when released back into the wild.

How Can You Make A Difference?

The easiest way to help is to make your home environment undesirable to rodents. Unclutter your living space – remove wood piles that are near your home unless they are enclosed in a rodent proof bin, remove available pooling water found in flower pots and drainage areas, repair all areas of access including broken basement windows, do not leave food around whether inside or outside your home (cat food on the porch for hours), and remove places that would appear inviting to a rodent as potential housing (old appliances on the lawn).

In addition, seek out accurate information when considering the use of a poisonous substance. Remember, all poisons are dangerous and we use them to obtain a desired result. However, those results may have unintended consequences – especially if your pet were to ingest the chemicals.

When hiring a pest control service, ask intelligent questions about the methods and chemicals that will be used to remove the rodents.

When you absolutely must use a toxic substance to remove pests, be aware of your timing. One of the Red-tailed Hawks necropsied by Tufts was carrying an egg and the well-developed blood vessels in her oviducts ruptured due to ingestion of the poison – she bled to death internally. Our actions do not only affect the current generation, but also generations to come.

Finally, seek out safer alternatives for pest removal. Visit the Audubon and the Department of Energy and Environmental Protection to learn more about the dangers of rodenticides and for additional information on safer alternatives and non-chemical solutions.

Credits for information:  The National Pesticide Information Center (NPIC), Department of Energy and Environmental Protection, the Audubon Magazine article “Poisons Used to Kill Rodents Have Safer Alternatives” by Ted Williams and Tufts Cummings School of Veterinary Medicine.