The rodent birth control landscape (Rethink Priorities)

At-a-glance

• Motivation: To understand the current practices in rodent pest control and identify levers to improve the welfare of the rodents.
• Scope: This paper describes the past and current rodent pest control landscape with a particular focus on harms of rodenticidal poisons and the possibilities for rodent birth control as a cruelty-minimizing alternative. Because rodent birth control is most available in the United States, the focus of this paper is primarily on the U.S.
• Welfare harms: Rodenticides, and in particular the anticoagulant rodenticides, are cruel to the rodents they are meant to kill as well as dangerous to humans, such as children, who accidentally ingest them and to predators who secondarily ingest the poisons their rodent prey have ingested.
• Ideal solutions: Controlling a “pest” population can also be achieved through reducing births, greatly reducing the need for lethal control means. Methods for reducing births include:
  • Resource reduction (by e.g. containing food waste)
  • Habitat reduction (by e.g. filling in abandoned burrows or filling in cracks that give access to the interior spaces of walls)
  • Effective birth control agents (such as EPA-approved ContraPest)
• Practical solutions: Rodent birth control can be used in concert with lethal control methods that are more humane than rodenticides, such as traps and asphyxiants that provide quick deaths. These methods and their relative humaneness and effectiveness are discussed.
• Ineffective solutions:
  • Most of the known chemicals that reduce rodent fertility have not been developed to be sufficiently effective, cost-effective, or safe to be competitive with lethal control agents.
  • Single-dose sterilants, which would completely abolish fertility in one dose, would come with a higher risk of overdose, bioaccumulation, and the evolution of resistance.
• Future directions: A follow-up post will focus on opportunities for impact via advocating the use of rodent birth control and the displacement of cruel pest control methods.