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

Abstract

Global estimates of the number of domestic cats (Felis catus) are >400 million. Issues associated with freeroaming cats are of global importance because of animal-welfare and public-health concerns and impacts on native wildlife through predation, competition and disease transmission. In the United States, proposed control solutions for managing urban free-roaming cat populations include euthanasia and trap-neuter-return (TNR) programs. We evaluated control methods using a demographic population model for a 25-year period, with parameters estimated from an unmanaged, free-roaming cat population in Texas. We modelled euthanasia and TNR at 25%, 50% and 75% implementation rates and a 50 : 50 combination of euthanasia and TNR at 25%, 50%, 75% and 100% implementation rates for 0%, 25% and 50% maximum immigration rates. We compared final population size, total number of cats treated and treatment effort relative to population reduction. Population decreases were comparable among euthanasia, TNR and a 50 : 50 combination for all treatment rates when the immigration rate was 0%; however, they were higher for euthanasia at 25% and 50% maximum immigration rates. Euthanasia required higher treatment effort than TNR. Our results indicate that immigration must be prevented and high (>50%) treatment rates implemented to reduce free-roaming cat populations.

Managing Feral Cats on a University's Campuses: How Many Are There and Is Sterilization Having an Effect?

“…High survival rate may indicate that feeding programs result in healthier and safer populations who are less at risk from trauma, disease, and starvation. Population models show that sterilization needs to exceed 50% (Schmidt et al, 2009) to 75% (Andersen et al, 2004) to effectively reduce cat populations, and even higher rates are needed to offset immigration.…”

“…Cat caretakers also reported a low immigration rate at the monitored colonies. Feeding programs may reduce competitive behavior for resources (Levy et al, 2003), increase carrying capacity, and lead to increased immigration (Schmidt et al, 2009); perhaps there are other factors explaining the low immigration rate. Cat caretakers' food was mostly eaten directly at feeding times with the remainder very well hidden.…”

Estimating feral cat densities using distance sampling in an urban environment

“…The study emphasized the need for scientific information to evaluate the effectiveness of this growing management method. The effectiveness of TNR programs on reducing cat populations has been found to be successful (Levy, Gale, & Gale, ; Lohr, Cox, & Lepczyk, ; Schmidt, Swannack, Lopez, & Slater, ). Trap‐euthanize programs are more effective at reducing colony size than TNR (Andersen, Martin, & Roemer, ; Lohr et al, ).…”

“…Trap‐euthanize programs are more effective at reducing colony size than TNR (Andersen, Martin, & Roemer, ; Lohr et al, ). However, Schmidt et al () found that both methods were comparable as long as treatment rates were greater than 50%. Domestic cat abandonment needs to be reduced for either method to be effective (Lohr et al, ; Schmidt et al, ).…”

Contraceptive Vaccines for the Humane Control of Community Cat Populations

“…Thus, a contraceptive treatment need not be effective in each animal, but a predictable effect at the population level is required. Most cat control models suggest that approximately 70–80% of female cats in a population must be rendered infertile to induce a decline in population size 22–25…”