The impact of habitat fragmentation on the ecology of xenarthrans (Mammalia) in the Brazilian Cerrado

Abstract

The impact of deforestation and fragmen- tation upon ecologically important and poorly known groups is currently an important issue for conservation biology. Herein we describe xenathran communities across the Brazilian Cerrado and study the effects of habitat fragmentation on occupancy and activity patterns on these assemblages. Our hypothesis was that larger and specialized species would be more ecologically sensitive, and likely to exhibit shifts in their activity patterns in more deforested areas as a way of dealing with the myriad of effects involved in the fragmentation process. The study was conducted by camera trapping in ten Cerrado sites. Five species were analyzed: Priodontes maximus, Euphractus sexcinctus, Dasypus novemcintus (Order Cingulata), Tamandua tetradactyla and Myrmecophaga tridactyla (Order Pilosa). Fragmentation was quantified by landscape metrics, calculated on scales that matched the species' home ranges. Occupancy and detection probability analyses were conducted to test for shifts in occupancy under different fragmentation condi- tions. A mixed-effects model analysis was conducted to test for shifts in species' frequency of records related to time of day, controlling for spatial autocor- relation by means of eigenvector-based spatial filters for the models' residuals. There were no changes in activity pattern between more and less fragmented areas, so that our behavioural plasticity hypothesis was not corroborated for this group. The lack of changes in the patterns could be explained by a species' time-lag response, or by the lack of a wide enough fragmen- tation gradient in our study.