Implementation of a targeted trap-neuter-return programme to manage the population of free- roaming cats (Felis silvestris catus) on Flores Island, Azores

Abstract

Background The negative impact posed by the uncontrolled growth of free-roaming cat populations, namely spread of diseases, public nuisance, and predation of wildlife, has prompted the development of ethical solutions to control cat populations. Science-based solutions such as Trap-Neuter-Return (TNR) programmes are the most efficient way to humanely manage free-roaming cats populations. While Portugal has sporadically employed TNR initiatives, no formal evaluations of its effectiveness were performed. We report the implementation of a concerted and targeted TNR initiative to control free-roaming cats population. This large-scale study took place on Flores Island, Azores, where a survey was conducted across its eleven parishes to assess cat colonies location and population density. Free-roaming cats were captured and transported to the official animal collection center of Lajes das Flores, where they were weighted and screened for any potential contraindication surgery. After induction of anaesthesia, the veterinary surgeons assessed cats eligibility through clinical examination. Animal data was collected to record gender, weight, age, body condition score, presence of ectoparasites and endoparasites, respiratory and intestinal signs, skin, mouth and ocular lesions, pregnancy and lactation status and general health status. Results During this study, 751 targeted free-roaming cats were trapped, desexed and then returned to their original colonies. Previous to our intervention, Flores Island housed a population of approximately 981 free-roaming cats, with only 2.34% (23/981) being desexed. Following the extensive targeted TNR activities, the cat population decreased slightly to 961 individuals with 80.54% (774/961) having undergone spaying or neutering procedures. This achievement surpassed the threshold for successful TNR initiatives. Conclusions Our findings underscore the efficacy of targeted TNR programmes as a practical and valuable ethical solution to manage cat population growth. These results provide valuable insights and guidance for the large-scale implementation of similar initiatives on other regions grappling with free-roaming cat populations.