Diet composition of Tyto spp. in the Florindo Donati Natural Protected Area, southern Santa Fe province, Argentina: assessing the sex and relative age of its prey

Abstract

The analysis of the pellet contents of raptor pellets is a suitable method to estimate the composition of the assemblages of micromammal species, as well as some of the parameters of their populations. The present contribution aims to establish a characterization of the trophic ecology of Tyto spp. establishing, in addition, the first records on sex determination and relative age of rodent prey in the Florindo Donati Natural Protected Area, Santa Fe province, Argentina. From the field work, a total of 46 pellets were recovered and 108 prey individuals were identified. The total number of species recorded corresponds to native rodents of the Cricetidae family. It was possible to establish a diet consisting of four species: Akodon azarae (Fischer, 1829), Oligoryzomys flavescens (Waterhouse, 1837) and Calomys spp. The genus Calomys was the dominant taxon (93.5 %). It was possible to establish a higher consumption of adult specimens (larger size) which may be the result of a maximization of net energy input by the predator. No differential predation by sex was observed. This study shows that diet analysis of Tyto spp. can be considered a tool to estimate the population abundance and distribution of small rodent species, avoiding other procedures, such as intensive trapping, which are potentially risky in terms of health and costly in time and effort.