Barn owl pellets collected in coastal savannas yield two additional species of small mammals for French Guiana

Abstract

A sample of 251 pellets regurgitated by the barn owl in an old building located in Sinnamary (French Guiana) provided a rare opportunity to get a preliminary inventory of small rodents and opossums living in grassy savannas along the coastal non-forested landscapes of this Guianan region. From a total of 329 specimens of vertebrate remains, we focused on 259 small rodents and opossums that could be positively identified. Two species previously unknown in French Guiana were evidenced: a very small opossum of the genus Cryptonanus and the medium-sized terrestrial rodent Sigmodon alstoni. Although Cryptonanus was an unexpected finding so far away from its Amazonian distribution area, the presence of Sigmodon in French Guiana fills a gap between Suriname and Brazilian Amapa where this species is typical of grassy savannas. The species of small mammals most commonly preyed upon by the barn owls of Sinnamary was a large semi-aquatic rodent, Holochilus sciureus, followed in decreasing order by two sigmodontines typical of non-forested ecosystems: Oligoryzomys fulvescens and Zygodontomys brevicauda. The analysis of owl pellets contents is a useful tool for providing an inventory of small mammal communities especially in open habitats such as agricultural landscapes or in cerrado-like biotopes (caatinga, savannas, llanos, grassy marshes, etc.) in the Neotropics Christoff 2007, Rocha et al. 2011). The barn owl [Tyto alba (Scopoli, 1769)] is a specialized predator and most of its preys are small non-volant mammals weighting from 15 to 250 g. Several recent investigations of barn owl pellets in Brazil and elsewhere in South America have evidenced the presence of some species of small rodents and opossums, which otherwise were very rarely caught by standard trapping methods using live-or snap-traps. KeywordsFor example, Souza et al. (2010) found two rare dwarf opossums [Gracilinanus agilis Burmeister, 1854, and Cryptonanus agricolai (Moojen, 1943)] among 162 pellets collected in the Northeastern Atlantic Forest realm, and those records were new for the coastal region of Pernambuco state. Similarily, Bonvicino and Bezerra (2003) found three rare species (two small opossums and one cerrado mouse) in barn owl pellets that could not be collected with traps, suggesting that trapping "was either inefficient or was not performed near their specific microhabitats". This study reports on barn owl pellets that were collected in an old water tower in downtown Sinnamary, French Guiana (05°23′N; 52°57′W) in March 2011 (120 pellets) and in September 2013 (131 pellets). Sinnamary is a small city (3100 inhabitants in 2013) at ca. 100 km northwest from Cayenne; it is located within the coastal northern strip of the country, where non-forested areas, such as agricultural lands, grass and bush savannas, small thickets of trees, grassy swamps, and marshes, predominate. The nearest large area of well-drained tropical rainforest starts at 3-4 km southwest from the village and extends for dozens of kilometers toward the south [the for...

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

“…The analysis of owl pellet samples has been considered a useful tool to inventory small mammals (e.g., Taylor, 1994;Bonvicino & Bezerra, 2003;Torre et al, 2004;Pardiñas et al, 2005;Teta et al, 2010;Meek et al, 2012;Baglan & Catzeflis, 2016;Mancini et al, 2018). In addition, it is a relatively easy and low-cost method that generates estimates of species richness that are identical or higher than those obtained by expensive traditional methods (e.g., trapping; Torre et al, 2004).…”

An Annotated Checklist of Recent Opossums (Mammalia: Didelphidae)

“…Of the five species originally referred to Cryptonanus by Voss et al (2005), only four are now recognized as valid. Currently recognized species of Cryptonanus are all from south of the Amazon (in Brazil, Paraguay, Bolivia, Uruguay, and Argentina), but specimens of a possibly undescribed species have been reported from Amapa (Silva et al, 2013) and French Guiana (Baglan and Catzeflis, 2016). REMARKS: For an emended description see Voss et al (2005), who also tabulated measurement data from eight referred specimens.…”

The Amazonian Savannas of French Guiana: Cultural and Social Importance, Biodiversity, and Conservation Challenges

“…Cryptonanus nov sp., strictly dependent on savannas, is listed as "Endangered" regionally ( UICN France et al, 2017). While this species has not been evaluated internationally (IUCN, 2019), it has only been described from bones collected from owl pellets in Sinnamary (Baglan & Catzeflis, 2014), though it may also occur in the Savannas of Amapa´, in eastern Brazil (Catzeflis, Silva, & de Thoisy, unpublished data). Clearly, the fate of a species endemic to savanna habitats is intimately linked to the fate of the savannas themselves.…”

“…While 55 of the 197 terrestrial mammals of French Guiana are found in savannas, only two are dependent on savannas: the small marsupial Cryptonanus nov sp. (Baglan & Catzeflis, 2014) and Sigmodon alstoni (Voss, 1991), both of which are considered endemic to the Amazonian savannas (Mustin et al., 2017). Cryptonanus nov sp., strictly dependent on savannas, is listed as “Endangered” regionally (UICN France et al., 2017).…”