Quantifying the presence of feral cat colonies and Toxoplasma gondii in relation to bird conservation areas on O'ahu, Hawai'i

Abstract

Free-ranging feral cats (Felis catus) are increasingly found in colonies loosely managed by people. These colonies increase cat densities and, hence, pose threats to wildlife via disease and predation, particularly in insular ecosystems where native species have smaller populations and reduced pathogen exposure compared to continental systems. Given such concerns, our objectives were to: (a) identify feral cat colonies on the island of O'ahu in the vicinity of important native bird sites;and (b) test for Toxoplasma gondii, a parasite-causing disease (Toxoplasmosis) of concern to native birds, at cat colony sites. We identified 32 important native bird locations and surveyed public lands near these sites to determine presence of cat colonies. Where cat colonies were present, we collected feces and used molecular tools to identify the presence of T. gondii. We identified 25 cat colonies near an important bird area and collected feces at four of these colonies, with three testing positive for T. gondii. The presence of cats near a majority of native bird areas suggests that cats may impose a serious threat to bird species. Our finding of T. gondii at three of the four colonies where cat feces were collected raises serious health concerns for humans, birds, and many other terrestrial and aquatic organisms. Native birds in Hawai'i, including highly endangered species, are susceptible to both predation and T. gondii, and finding its presence in locations relatively near to important native bird areas provides further evidence that reducing freeranging feral cat numbers is critical for reducing impacts on birds. K E Y W O R D Scat colony, Felis catus, invasive species, island ecosystems, Toxoplasma gondii

Epidemiologic significance of Toxoplasma gondii infections in turkeys, ducks, ratites and other wild birds: 2009–2020

“…Thus, 11 geese died of toxoplasmosis. The presence of cats in colonies near the native bird sites is thought to be a source of T. gondii oocysts for the birds (Lepczyk et al , 2020).…”

Identification of the population source of free-ranging cats threatening endemic species on Tokunoshima Island, Japan

“…In particular, the impact of predation on native species by cats is serious on islands where no predatory mammals were historically present (Bonnaud et al 2011;Medina et al 2011;Nogales et al 2013;Courchamp et al 2003), contributing to the extinction of at least 63 vertebrate taxa (Loss and Marra 2017). Other issues related to free-ranging cats include the transmission of infections, such as toxoplasmosis and toxocariasis (Deplazes et al 2011;Macpherson 2013;Gerhold and Jessup 2013;Lepczyk et al 2020;Wilson et al 2020) or hybridization with the wildcat (Felis silvestris) (Pierpaoli et al 2003).…”

Dynamics and epidemiology of Toxoplasma gondii oocyst shedding in domestic and wild felids

“…Four domestic cat shedding studies were identified in island countries or continents where native wild felid species are absent, specifically New Zealand, Australia, and St. Kitts. In addition, two recent studies from the island of O'ahu (Hawaii, USA), where wild felids are also absent, detected T. gondii DNA in faeces from domestic cats (7% and 10.7% of cats tested), but these studies did not examine faeces microscopically for the presence of oocysts (Davis et al., 2018; Lepczyk et al., 2020).…”