Estudo das populações de pequenos mamíferos através da análise de egagrópilas de coruja-das-torres (Tyto alba)

Abstract

The study of small mammal populations can be carried out through direct methods involving their capture through traps, and indirect non-invasive methods such as camera trapping, prospecting and collection of signs of presence and analysis of barn owl's regurgitated pellets. The barn owl (Tyto alba) is a nocturnal bird of prey with a global distribution, with the exception of the Arctic regions. This species feeds mainly on small mammals that are ingested whole; the bone structures and fur are not digested during the digestive process and are later regurgitated in the form of an ovoid mass, called an regurgitated pellets. The content of the pelletss contains all the undigested structures of the prey and the identification of the species of small mammals is carried out through their teeth. The analysis of the barn owl's diet reflects the diversity and abundance of small mammals captured in its hunting territory, and is a valuable and widely used method for estimating the relative abundance of prey in a given region. There are numerous species of small mammals that can be studied in northern Portugal, namely the white-toothed shrew (Crocidura russula) and the red-toothed shrew (Sorex granarius) from the order Soricomorpha, and the blind mouse (Microtus lusitanicus), the Portuguese field mouse (Microtus rozianus) and the Cabrera mouse (Microtus cabrerae) from the order Rodentia. The populations of small mammals between the different bioclimatic regions of Portugal are important for studying rodent populations and evaluating conservation strategies that consider the climatic and environmental particularities of each region. Protecting the natural habitats of regions is crucial to maintaining biodiversity and ensuring the survival of species, in a logic of sustainable development.