2013 July Nature News – Second-generation rodenticides and wildlife: A deadly combination


Anticoagulant poisons work by inhibiting the proteins required for blood clotting. The result for any animal ingesting these poisons is internal hemorrhaging. The poisoned animal slowly dies from internal bleeding, all while being able to move around the environment – albeit slowly – for up to 10 days. That makes poisoned rodents easy prey and more likely to be caught and ingested by a predator – owls, foxes, cat, dogs, hawks, etc. These unlucky predators then face the same fate as their prey – a slow death by internal bleeding.

If you have a rodent problem, PLEASE consider alternatives to poison.

Things you can do:

  • Limit rodent access to your home.
  • Fill small outside holes with steel wool.
  • Make sure all food sources are covered and in metal containers (dog/cat food, livestock feed, bird seed).
  • Clean up under bird feeders regularly.
  • Keep compost bins covered.If possible on your property, encourage natural rodent control by putting up barn owl, screech owl or kestrel boxes to provide predator nesting sites. A pair of barn owls raising even one clutch of five youngsters a year can eliminate thousands of mice and rats in a safe, environmentally sensitive way.
  • Use snap traps for catching rodents – they are quick and considered humane. Avoid glue traps, as they are a particularly inhumane way to die. It might be distasteful having to see and dispose of the results of a successful snap trap – but after all, you ARE trying to kill them. This way you know you are successful; you know the rodents are not dying in your wall or poisoning the predators in your area.
  • Trapping should be undertaken with care. Traps should never be set where children, pets, wildlife or domestic animals can be injured by them. Set traps in a safe, covered spot. Two of the most effective baits to use are peanut butter or pumpkin seeds. Give rats and mice time to enter traps and take baits in traps, so be patient.

Poisons should always be used as a last resort rather than a first line of defense. If the problem is such that you must resort to using a poison, please consider selecting a first-generation bait with these active ingredients: chlorophacinone, diphacinone, diphacinone sodium salt, warfarin, and warfarin sodium salt. Whenever you use a poison, always follow the safety precautions.

Remember that the use of poison can cause the natural balance to actually tip in favor of the pest if the poison is secondarily killing keystone predators such as hawks and owls.

Please consider the impact on the environment before reaching for any toxic chemical, whether it is a weed-and-feed product or rodenticide. Your wild neighbors will be grateful!

Resources for this article: Audubonmagazine.org (Jan/Feb 2013 “Building A Better Mousetrap”; eraptors.org; raptorsarethesolution.org; hungreyowl.org


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