Species composition, abundance and diet of a squamate assemblage from the Carnaval stream headwaters (Buenos Aires, Argentina)

Abstract

The present work summarizes 10 years of field observations of an exurban squamate assemblage occupying a 1200 ha patch in the suburbs of La Plata City (Los Porteños, Buenos Aires, Argentina). Crossed by two streams (Martin and Carnaval), the area is characterized by intensive horticulture and floriculture, poultry and pig farming, exhibits a low housing density (1 house/ha), and the roads are largely unpaved. This area is under stress due to continuous expansion of the neighboring city in detriment of rural areas, determining a stressing environmental scenario. Field data were complemented and contextualized with museum records of the squamates present in the area and in neighboring departments of La Plata. The field-based species list of squamates from Los Porteños comprises one amphisbaenian (Amphisbaena darwinii = 26 specimens), five snakes (Paraphimophis rustica = 24, Xenodon dorbignyi = 6, Erythrolamprus poecilogyrus = 3, Erythrolamprus semiaureus = 2, Lygophis anomalus = 1), and one lizard (Salvator merianae = 11). The number of species of squamates in Los Porteños was higher than the expected compared with the species from surrounding areas. Fossorial, nocturnal and generalist species were the most abundant in Los Porteños. These urban adapter species lack dietary constraints and their living habits minimize the encounters with humans, who commonly kill them.