Assessing the impact of free-ranging cats ( Felis silvestris catus ) and dogs ( Canis lupus familiaris ) on wildlife in a natural urban reserve in Mexico City

Conservation of natural ecosystems embedded in urban contexts is a big challenge because diverse anthropogenic factors continuously impact native biodiversity and ecological processes. One such factor is the pervasive presence of free-ranging predators, especially cats ( Felis silvestris catus ) and dogs ( Canis lupus familiaris ), which may severely affect local wildlife. The “Reserva Ecológica del Pedregal de San Ángel” (REPSA), located within the main campus of the Universidad Nacional Autónoma de México (UNAM), in southern Mexico City, is an important natural area that protects a peculiar volcanic spill ecosystem holding native and endemic biodiversity. In 2012, UNAM launched a control program of cats and dogs in REPSA that is still active. To assess the potential impact of cats and dogs on wildlife species, we used live and camera traps coupled with capture-recapture analyses to evaluate changes in the vertebrate community, particularly in the presence and abundance of two medium-size native mammals ( Didelphis virginiana and Bassariscus astutus ), before (2008–2009) and during (2017–2019) the control program. Results showed that the abundance of dogs decreased between the two periods, but not so the abundance of cats, whereas the native vertebrate diversity increased from the pre-control stage to the control period. Furthermore, we found a negative, non-significant relationship between the abundance of D. virginiana and that of dogs, and a positive, also non-significant relationship between the presence and abundance of B. astutus with the abundance of dogs. We conclude that the control program of free-ranging predators has been beneficial for the conservation of native vertebrates and recommend its continuation and enhancement.