The demographic consequences of fertility reduction in rats and voles

Abstract Rodent population control is a global problem, complicated by evolved non-responsiveness to rodenticide treatment. Contraceptives could help mitigate this challenge, but questions remain about their efficacy, especially for rodenticide-resistant populations. We used an age-dependent demographic model generate two hypotheses: Fertility reduction applied early in female lifetimes (1) more effective controlling rodent populations than when later lifetimes, and (2) that are expanding. Compared controls, fertility early, mid-life, late decreased, matched, accelerated, respectively, the rates of growth. was reducing size only sustained over multiple generations ineffective application episodic. Substituting classic Rattus norvegicus Microtus agrestis life history data into our simulation framework confirmed growth, including expanding both species. These simulations generated additional hypotheses field applications control: Over treatment durations, (3) fraction consisting juveniles, (4) overall size, will decrease. tested these predictions using 12-month contraceptive bait on rats urban US locations (Washington, DC) where rodenticides were already deployed. Consistent with predictions, showed marked decreases proportion juvenile adult rats, total number observed camera traps study period. Our results support as method managing