Densidade populacional do lagarto endêmico Cnemidophorus littoralis em três restingas do estado do Rio de Janeiro: implicações na sua conservação

Abstract

Cnemidophorus littoralis is a teiid lizard endemic to restingas and restrict to the state of Rio de Janeiro, being found only in four restingas: restinga de Grussaí (north limit), restinga de Jurubatiba, restinga de Maricá e restinga de Marambaia (south limit). Its current conservation status is "in danger". Due to its restricted distribution, the effects of hábitat degradation and climate changes are specially harmful to individuals of this species, which may lead to local or even total extinction. In order to raise the level of information about this lizard species, we investigated the population density and population size in three areas of restinga, besides recording the temperatures to which they are subject in different micro-hábitats available as well as their preferences for certain vegetation structures and the current situation of degradation of restingas, comparing it to the previous years. The present study took place in Barra de Maricá (Maricá), Jurubatiba (Macaé) and Grussaí (São João da Barra). The results showed a difference between the vegetation structures of the three restingas, being restinga de Grussaí the most different one. This restinga is also the one with the lowest density and the highest degradation index. On the other hand, restinga de Jurubatiba was the site where we found lowest disturbance, having the highest density among the three and being characterized as the best area for the maintenance of the species. The litter on the edges of bushes was, overall, the hábitat most widely used by lizards, and the period between 10:00 am and 11:00 am was the one when most of the sightings ocurred. Shrub height showed a negative effect on the occupation of the individuals in restinga de Grussaí, while the periods of observation along the day influenced the detectability of individuals in the three restingas. The restingas had similar temperature throughout the day, Maricá being the one with highest average temperature (34,6ºC), followed by Grussaí (33,9ºC) and finally Jurubatiba, with 33,2ºC average. The body temperature to which the individuals were subject in the micro-hábitats ranged from 27ºC (litter above vegetation) to 42,5ºC (bare sand) in Grussaí, and from 28ºC (litter inside shrub) to 32,9ºC (bare sand) in Jurubatiba. Since environmental structure influences the thermal characteristic of lizards, hence maintaining populations, conservation of restingas and its vegetation structures are essential for the perpetuation of the species