Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats

Abstract

Free-roaming cat populations have a high intrinsic growth rate, and euthanasia is estimated to be more effective at reducing cat populations than trap-neuter-return programs.

An Evaluation of Feral Cat Management Options Using a Decision Analysis Network

“…A brief internet search through Google turned up less than five cat sanctuaries in the U.S. today. http://www.ecologyandsociety.org/vol15/iss4/art10/ Andersen et al (2004) predicted effective cat control through annual spaying/neutering of at least 75% of the population. Simulation exercises conducted to develop the population dynamics within this model also predicted that a 75% monthly capture rate would allow for population stabilization, whereas 50% monthly capture rates would fail to prevent chronic population increases unless supplemented with kitten removal.…”

“…Norris et al (2007) found rates of feline immunodeficiency virus (FIV) to be more than twice as high in unowned cats and Nutter et al (2004a) recorded significantly higher rates of bacterial infection and parasites in feral cats when compared to pet cats. Feral cats are subject to environmental extremes, vehicle trauma and predation, all of which contribute to high mortality rates (Nassar and Mosier 1982, Warner 1985, Andersen et al 2004, Nutter et al 2004b) and relatively short lifespans (Warner 1985). This has led some animal rights groups to promote euthanasia as the most humane management option Whether stakeholders are motivated by concerns for wildlife, cat welfare, or human health, there is general agreement that the number of abandoned and feral cats must be reduced.…”

Evaluation of euthanasia and trap - neuter - return (TNR) programs in managing free-roaming cat populations

“…Inclusion of both sexes is also important if male and female vital rates are different (Andersen et al 2004). For our study population, we found evidence that male and female mortality rates differed (Schmidt et al 2007a), thus requiring a population model evaluating male and female contributions to population growth rates.…”

“…Lethal and non-lethal population-control strategies are expected to alter vital rates (Conover 2002); therefore, the evaluation of population-control methods for unmanaged cat populations ideally should be conducted a priori using vital-rate estimates from unmanaged cat populations (White 2000). Wildlife ecologists commonly use population models as decision-making tools to assess various management scenarios to control invasive and introduced species (Gogan et al 2001), including free-roaming cats (Andersen et al 2004;LaFever et al 2008).…”

“…Implementation of euthanasia or TNR would realistically include treatment of male and female cats. The effects of each control scenario on male and female vital rates and the subsequent effects on population growth have not been considered in prior modelling attempts (Andersen et al 2004).…”