Population characteristics and movement of native and exotics turtles in urban area

Abstract

The impacts from urban areas may result in alterations in environmental characteristics and wild populations dynamics. Therefore, we aimed at assessing population size, density, home range, maximum range of movement and habitat selection of native and aliens freshwater turtles in a Brazilian urban park (Phrynops geoffroanus-PG, Trachemys dorbigni-TD, Trachemys scripta elegans-TSE). We applied capture-mark-recapture procedures from July/2016 to August/2018. Home ranges were estimated from trap locations using a 100% minimum convex polygon (MCP) method, and habitat selections using eigenanalysis. We sampled 41 PG, 35 TD, and 20 TSE. Population size was estimated as 59 ± 7.6 (PG), 36 ± 1.4 (TD), and 20 ± 0.5 (TSE) individuals (± SE), with a density estimates of 1.36 (0.34), 1.72 (0.36), and 0.87 (0.25) individual/ha (± SE), respectively. Home ranges size ranged between 0.04 ha and 0.48 ha, the highest distance was reached by D'Orbigny's slider (525.8 m). Our results indicate that habitat preferred for all species is clearly influenced by human presence, and the turtle assemblage exhibit strategies as temporal segregation to coexist on this small, closed park. Both the presence of two established populations of invasive alien species and the changing movement of freshwater turtles reflect anthropic pressure on wild population dynamics and the lack of effectiveness of environmental policies and inspection in Brazil. The understanding that wild populations are being affected even in conservation units could be considered by the managers implement monitoring of target wild populations, control of exotic species, insertion of educational signs and actions, and control of visitors.