Impact of exotic mammals on biodiversity and health in the French West Indies: focus on Felis catus

Abstract

Island ecosystems are facing numerous threats, among which biological invasions stand out as a major concern. Invasive species impact biodiversity in various ways, including competition, predation, hybridization, and the transmission of diseases and parasites (Simberloff et al. 2013). Besides, free-ranging or feral domestic species can exert similar pressures on native ecosystems, further amplifying ecological impacts (Doherty et al. 2016). Beyond these ecological consequences, invasive and feral species also induce significant economic losses, both through damage to agriculture and the costs associated with their control or eradication (Bodey et al. 2023). These ecological issues are particularly significant in the Caribbean islands, where all islands are impacted by at least one invasive and/or feral species (Kairo et al. 2003). In the French West Indies, several invasive and feral species have become common across various habitats. However, their exact impacts on native ecosystems and their spatial distribution remain poorly documented. To address these gaps, a recent project led by Caribaea Initiative (CIMBA - Controlling the Impact of Exotic Mammals on Biodiversity in the Antilles, https://cimba-project.org/en/the-project/), supported by the Interreg program, aims at studying exotic predatory mammals in the Caribbean region. Studied species include the domestic cat ( Felis catus ), originally introduced as a pet; the small Indian mongoose ( Urva auropunctata), introduced to control rat populations and now one of the most invasive species in the Caribbean; and the raccoon ( Procyon lotor minor ), introduced in the early 19th century. As part of this project, my Ph.D. project is investigating the spatial distribution and the impact of these species in Guadeloupe and Martinique based on an extensive camera trap survey deployed across both natural and semi-natural environments. Statistical analyses are used to estimate the relative abundance of each species and their spatial and temporal co-occurrence patterns. The co-occurrence with ground-dwelling bird species, which could be preyed upon by the studied feral and invasive species, is also examined. In parallel, we conduct additional investigations focusing specifically on cats. First, dietary analyses based on stomach contents or feces are conducted to identify prey species and evaluate predation pressure on local biodiversity using metabarcoding approaches. Additionally, bacteriological cultures performed on the same samples aim to detect antibiotic-resistant Escherichia coli strains in order to identify potential reservoirs in wild fauna and assessing the risk of dissemination to human health. In this presentation, we share preliminary findings on the abundance and distribution of cats, mongooses, and raccoons in Guadeloupe, as well as ongoing approaches to quantify the ecological impacts and the level of carriage of extended-spectrum β-lactamase-producing E. coli in cats . This work provides new insights into the dual ecological and sanitary impacts of invasive mammals in island ecosystems and contributes to informing conservation and management strategies in the Caribbean.