Reptiles preyed by the Burrowing owl (Athene cunicularia): new records and current knowledge in South America

Reptiles are largely preyed by other reptiles, mammals, and birds, including birds of prey (Alencar et al. 2012, Spencer et al. 2014, Cortes-Gomez et al. 2015). Consequently, reptiles developed a set of defense mechanisms to avoid predation, such as cryptic or aposematic coloration (Caro 2014). However, these strategies may not always be efficient, especially against specialized birds of prey. There are records on birds of prey finding, capturing, and ingesting different cryptic or aposematic reptiles (Fowler et al. 2009), including serpentiform and venomous preys (DuVal et al. 2006, Bastian et al. 2008, Carevic 2011, Medrano-Vizcaíno 2019). Some examples are a Laughing falcon Herpetotheres cachinnans preying on a venomous Amazonian Pit viper Bothrops atrox (Medrano-Vizcaíno 2019) and a Burrowing owl Athene cunicularia (Molina 1782) preying on a cryptic lizard Liolaemus occipitalis (Zilio 2006), an aposematic snake Phalotris mertensi (Cruz et al. 2014), and a venomous Crossed Pit viper Bothrops alternatus (Martins et al. 2003). However, the successful predation on venomous snakes

involves strategies that enable the predator to survive, when faced with this type of prey, highlighting the relevance of efficient prey recognition and handling (Wall & Shine 2007, Parker et al. 2012.
The Burrowing owl is a small-sized and diurnal bird of prey associated with open habitats. It is found in human-modified areas, such as pastures and semi-urban areas, and is widely distributed in the Americas, occurring from southern Canada to southern Argentina and Chile (Sick 1997). It is a generalist and opportunistic predator that feeds mainly on invertebrates such as insects and small vertebrates, such as rodents (Motta-Junior 2006, Cadena-Ortíz et al. 2016, Holt et al. 2018. Amphibians and reptiles (Squamata) were also recorded in their diet, yet less frequently (Silva-Porto & Cerqueira 1990, Vieira & Teixeira 2008, Andrade et al. 2010). The differences on the ingestion of these prey may be influenced by the seasonal variation in the resource availability throughout the year. In Chile, insect consumption is higher during winter https://doi.org/10. 17648/heringeriana.v15i1.917956 (May through September), while small reptiles and mammals are more frequently found in the diet during summer (October through April) (Carevic et al. 2013).
Despite the great variety in the Burrowing owls' diet (Motta-Junior 2006, Andrade et al. 2010, Cadena-Ortíz et al. 2016, Holt et al. 2018), few studies have been able to assign preyed items to species level. The lack of fine-scale taxonomic resolution for some prey species is because most studies are based on pellets analysis (Motta-Junior et al. 2015), and some prey types, such as soft-bodied or small animals, are quickly digested and are rarely identified in these pellets. This matter limits further conclusions on foraging strategies and prey selection, especially of potentially dangerous or concealed prey, such as some reptiles. We provide three new Scholar. The combination of the terms "Athene cunicularia" or "Burrowing owl" plus "diet" or "predation" or "feeding" were used. We also searched for new records considering the reference list of the survey papers.
In the morning of February 16 th , 2019, at Parque Nacional de Brasília, a tail of Ophiodes aff.
striatus was found at the entrance of a Burrowing owl's hole (15°40'23.6"S, 47°56'56.5"W, WGS84), in an area surrounded by "cerrado" sensu stricto (Fig.   1A). On February 18 th , 2019, in the same area, a specimen of Oxyrhopus cf. trigeminus was found with its head missing at another Burrowing owl's hole, ( Fig. 1B-C). On the morning of December 17 th , 2020, at Universidade de Brasília (UnB), a juvenile Burrowing owl was observed preying a specimen of Oxyrhopus rhombifer, also with its head missing, near the parking lot of the Computer Science Department building (15°45'29.9"S, 47°52'08.5"W, datum WGS84). The owl was pecking lightly at the snake's body and eventually, when a piece of tissue was taken from the snake's body, it was immediately swallowed   In our literature review, we found publications from 1928 to 2020, covering almost 90 years of research. However, only 22 articles reported reptiles as part of the Burrowing owls' diet. We found 15 predation records in Brazil, being the country with the highest number of records, followed by Chile (eight), Argentina (four), Peru (three) and Ecuador (two). In total, 32 species (Squamata) were registered as prey, including our records. Lizards represented the most diverse species of prey (n = 21 species; 65,62%) distributed in nine families, followed by snakes (n = 10 species; 31,25%) in three families, and just one species (3,12%) of amphisbaenid (see Table 1). Considering only snakes (n = 10), 70% of the consumed species were aposematic Colubridae, whilst only 20% corresponded to venomous Viperidae species, in which all were from genus Bothrops. Nevertheless, some visually oriented predators, such as birds, can still locate and prey on cryptic species, e.g., the Great tit Parus major that prey on cryptic larvae and pupae of Swallowtail butterfly (Iphiclides podalirius) (Stefanescu 2000). The survival of cryptic prey is related with background and the ability to remain immobile in the presence of the predator (Loannou & Krause 2009). Also, small movements can be enough for visually oriented predators to detect their prey (Stefanescu 2000).
In order to deceive predators, some non-  (Niskanen & Mappes 2005) and seems to be effective against dangerous snakes (Parker et al. 2012). This behavior was seen in generalist predators like the Burrowing owls (e.g., Martins et al. 2003)