Small mammal diversity in Semi-deciduous Seasonal Forest of the southernmost Brazilian Pampa: the importance of owl pellets for rapid inventories in human-changing ecosystems

Abstract

The Pampa biogeographic province covers a mere 2% of the Brazilian territory (176,496 km²). However, it stands out as a complex and diverse ecosystem, although its mammal communities are still scarcely understood. Human activities are transforming the territory into a mosaic of agroecosystems, native and exotic forest fragments, and grasslands. Here we conducted the first investigation to determine the richness of small mammal assemblages in the region based on extensive analyses of owl pellets (Tyto furcata). Craniodental remains were studied from samples collected from 12 Semi-deciduous Seasonal Forest sites in the municipality of São Lourenço do Sul, State of Rio Grande do Sul, Southern Brazil. A total of 2,617 individuals belonging to 19 taxa were recorded, including 2 marsupials (Didelphidae; 0.42%), 2 chiropterans (Molossidae, Phyllostomidae; 0.12%), and 15 rodents (Cricetidae, Muridae, Caviidae; 99.46%). The rodent genera Oligoryzomys, Mus, Calomys, and Akodon were the most common taxa. Large samples also included poorly known taxa, such as the cricetids Bibimys, Juliomys (recording here its southernmost occurrence), Lundomys, and Wilfredomys. From a biogeographical point of view, the recorded assemblage embraces a mixture of Platan, Pampean, and Atlantic Forest elements, highlighting the role of the southernmost Brazilian hills as a wedge favoring the penetration of forest micromammals to higher latitudes. Our findings testify to the great diversity of the Pampa, but also point to a growing homogeneity and dominance of rodent species that are widespread in agroecosystems. Rapid inventories based on owl pellets emerge as a suitable, economic, non-invasive tool to document these community changes.

Small mammals in the diet of Barn Owls (Tyto furcata) in an urban area in Rio de Janeiro state, Brazil, with a new record of the dwarf mouse opossum (Cryptonanus)

“…Several studies have emphasized the use of owl pellets in small mammal inventories in natural areas harboring high richness of rare species seldomly sampled by conventional trapping methods (Bonvicino and Bezerra, 2003;Heisler et al, 2015;Lemos et al, 2015;Stutz et al, 2020;Torre et al, 2004). Our study highlights that owl pellets are useful to record rare mammals also in urban and highly disturbed areas dominated by invasive species.…”

“…In localities of Rio Grande do Sul state, Mus musculus accounted for more than 80% of the mammals preyed by Barn owls, despite the presence of a rich assemblage of native species in the diet items (Scheibler and Christoff, 2007;Stutz et al, 2020). Likewise, in the Parque Nacional da Restinga de Jurubatiba, Mus musculus continued to be one of the most preyed rodents, although presenting lower relative abundance (39.6%) compared to the Rio Grande do Sul localities (Lemos et al, 2015).…”

“…Owing to the fragmentary state of most skulls, the most reliable structures for taxonomic identification of rodents and marsupials consisted in molars. The identification of specimens was then based on diagnostic dental characters proposed by the taxonomic literature on Neotropical marsupials and rodents (Gonçalves et al, 2015;Percequillo, 2006;Pires et al, 2016;Stutz et al, 2020;Voss, 1991;Voss et al, 2005;Voss and Jansa, 2009), and also based on comparisons with voucher specimens in the mammalian collection (NPM) of the Institute of Biodiversity and Sustainability, Federal University of Rio de Janeiro (NUPEM/UFRJ). The number of preys was estimated by counting the most numerous individual bone element (e.g., left mandible) found in the sorted pellet material (Lemos et al, 2015).…”

Small mammals (Rodentia) present in Tyto furcata (Temminck, 1827) (Strigiformes, Tytonidae) pellets from the Reserva Natural da Guaricica, Antonina, coastal Paraná, Brazil

“…Inspired by the exemple of successful inventories (Stutz et al, 2020;Cherem et al, 2018;Lemos et al, 2015), which used bones and teeth present in pellets of owls in South America to access the diversity of small mammals, this research aimed to assess the rodent diversity in Reserva Natural da Guaricica (RNG). It has 8,600.32 ha entirely located within the municipality of Antonina, on the coastal plain, eastern Paraná State, Brazil (25°24'-25°41'S, 48°64'-48°74'W).…”