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

One method to determine the presence of non-flying small mammals is the use of owl pellets or regurgitates. Tyto furcata is an owl species found in many types of environment, varying from untouchable forests to urban areas. The species has typical nocturnal habits and a varied diet of mammals (including rodents, marsupials, bats), amphibians, reptiles, and even other birds (Machado, 2011) and has been shown to move on average 1 km (rarely 2 km) from the nesting site to foraging areas (Taylor, 1994).

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). It is in one of the largest continuous remnants of the Atlantic Forest in Brazil, preserving natural vegetation formations of the Dense Ombrophilous Forest. However, 1,500 ha are of degraded areas in recovery process. The climate of the region is classified as Cfa, subtropical humid mesothermic, according to the Köppen system.

Sampling of T. furcata pellets began in July 2015 and was performed every two weeks for twelve months. The pellets were found in the Centro de Educação Ambiental (CEA), which is a building used as a perch and main nest. Each collected pellet was packed in a plastic bag, numbered and labelled with date and location. For the preparation of the pellets, they were immersed in 70% alcohol for two hours, followed by separation of the osteological remains from hairs. Specimens were identified based on cranial structures and teeth (incisors and molars) observed under a microscope and compared with the reference collection of Biodiversity Conservation Laboratory from Universidade Federal do Paraná (UFPR).

A total of 2,900 pellets were collected, as most pellets didn’t contain enough cranial structures for identification, we recovered 133 individual rodents representing seven taxa: Oligoryzomys sp., Nectomys squamipes (Brants, 1827), Akodon sp., Holochilus brasiliensis (Desmarest, 1819), Brucepattersonius sp., Oxymycterus sp. and Euryoryzomys russatus (Wagner, 1848) (Figure 1). Quadros and Tiepolo (2003), and Silveira (2012), employed conventional trapping methods in RNG, and registered altogether 11 species in Rodentia. Four of the genus present in our samples, Nectomys, Brucepattersonius, Holochilus and Oxymycterus, were not present in those samples. The orders Didelphimorphia and Chiroptera, one bird and one Anura were also present in the owl pellet samples, but exceedingly rare and difficult to identify.

Figure 1
Skulls found in Tyto furcata pellets from the Reserva Natural da Guaricica, identified by genus. Left to the rule, skulls are shown in dorsal view. Right to the rule, skulls are shown in ventral view.

Quadros and Tiepolo (2003) and Silveira (2012) were more successful in sampling and identifying not only Rodentia (11 species), but also Didelphimorpha (6 species) using conventional traps. Eight genus of Rodentia were absent from our samples, in some cases, because they are too large or more diurnal species to be prey by T. furcate: Sciurus aestuans (Linnaeus, 1766), Hydrochaeris hydrochaeris[Linnaeus, 1766], Cavia aperea Erxleben, 1777, Dasyprocta azarae Lichtenstein, 1823, Agouti paca (Linnaeus, 1769). In three cases, the absent species were a potential prey of T. furcate: Delomys dorsalis (Hensel, 1872), Sooretamys angouya (Fischer, 1814), and Oryzomys sp.. Only three taxa were shared between all searches in reserve (O. nigripes, Akodon sp. and E. russatus). Absence of invasive species, as Mus musculus (Linnaeus, 1758) and Rattus rattus (Linnaeus, 1758) suggests that, despite more generalist species are present, area is characterized by low degree of disturbance.

The species Oligoryzomys sp. (83 individuals, 62%) and Akodon sp. (13 individuals, 10%) are frequent in areas that have suffered some type of perturbation (Pardini and Umetsu, 2006; Quintela et al., 2012). It makes sense, because 1,500 ha are of degraded areas in recovery process. N. squamipes (Brants, 1827) was the second most frequent taxon with seventeen individuals present in the pellets (13%). According to Oliveira and Bonvicino (2006), this rodent lives close to water courses. The present study recorded the occurrence of H. brasiliensis, (six individuals, 4%) which represents the first documented occurrence of this species along the north coast of the state of Paraná. The species of the genus Holochilus also inhabit humid areas close to water courses such as rivers, lakes and streams, and are typical of open areas in South America (Hershkovitz, 1955). The increase in areas irrigated by artificial channels and the abundance of tributaries of the Cachoeira river basin in the region favor the presence of N. squamipes and H. brasiliensis.

The genus Brucepattersonius (eight individuals, 6%) can be found in undisturbed and non-fragmented Ombrophilous Forest and Seasonal Deciduous Forest (Pardini et al., 2005). The species Euryoryzomys russatus (Three individuals, 2%) can serve as a habitat quality bioindicator, since it is strongly affected by the loss and fragmentation of forest (Pardini et al., 2005; Umetsu et al., 2008). This is one of the most common species in forests with excellent state of preservation in littoral of Paraná (Mochi-Junior, 2014; Gatto-Almeida et al., 2016). There were also three Oxymycterus (2%).

The current study area is during an ecological succession transition, since it was old cattle pasture, and its reforestation is recent. It is possible that the quality of its surroundings has enabled the occupation of sensitive species. This record shows the importance of using owl pellets for small mammal survey since the region has been intensively sampled over the past few decades without capturing this species by traditional methods. New information obtained here for the study area shows how important this method can be as alternative to traditional trapping inventories.

References

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Publication Dates

• Publication in this collection
  27 Aug 2021
• Date of issue
  2023

History

• Received
  28 Dec 2020
• Accepted
  06 Apr 2021