Herpetology Notes, volume 14: 209-213 (2021) (published online on 26 January 2021)

Predation by Leptophis ahaetulla (Serpentes: Colubridae) on Osteocephalus cabrerai (Anura: Hylidae), with a description of its distress call

Sarah Chaloupka1,* and Camilo Rodríguez2

Frogs are prey for many different organisms, including Osteocephalus cabrerai belongs to the O. buckleyi invertebrates, fishes, other amphibians, reptiles, birds, and complex (Moravec et al., 2009; Jungfer, 2010, 2011; mammals. One of the major predators of frogs are snakes, Ron et al., 2010). The species is arboreal and nocturnal and frogs have evolved a variety of antipredator strategies (Jungfer, 2010) and occurs in lowland tropical rainforest against them, including chemical defences (often across the Amazon basin, mostly on forest edges (La associated with bright coloration), cryptic colouration, Marca et al., 2004). During the day, individuals can be immobility, rapid escape, and distress calls (see the found hiding and sleeping under tree bark, on branches, review by Wells, 2007). Distress calls are produced by or in epiphytic bromeliads (Jungfer, 2010). frogs when caught by a predator (Bogert, 1960) and are On 13 February 2019 at 14:29 h we found an individual likely to alert conspecifics (Hödl and Gollmann, 1986; of L. ahaetulla moving across the forest floor on a river Leary and Razafindratsita, 1998). Here, we describe the island in the Nouragues Nature Reserve in French Guiana, predation of an adult Osteocephalus cabrerai (Cochran approximately 30 m from the­­­ Arataï River. We followed & Goin, 1970) by the parrot snake Leptophis ahaetulla the snake for a few meters and, after taking several photos (Linnaeus, 1758) in “Les Nouragues” natural reserve in of the­­ snake on the ground, it climbed up on a tree to French Guiana. Additionally, we describe the distress call a height of ca. 1.5 m. There, it attacked an O. cabrerai produced by O. cabrerai during the predation event. by grasping it from behind, turned it around within its Leptophis ahaetulla is one of the most widespread distended mouth, and then swallowed it head-first. The species of the genus Leptophis, occurring in Central and complete predation event, from attack to completed South America (Leenders, 2019). These semi-arboreal ingestion, lasted exact two minutes (14:32–14:34 hrs). snakes are harmless to humans, hunt during the day, and The characteristic bright blue posterior arm, thigh, tibia, feed predominantly on hylid frogs but also consume other and tarsus colouration of O. cabrerai (Jungfer, 2010) vertebrates (Beebe, 1946; Oliver, 1948, Albuquerque et could be observed while the frog was struggling to escape al., 2007; Alcantara et al., 2017). Five different hylid (Fig. 1). Later, several photos of the snake moving up genera (Dendropsophus, Hypsiboas, Osteocephalus, onto higher branches were taken, showing its swollen Scinax, Sphaenorhynchus) have been recorded among body (Fig. 2). stomach contents of L. ahaetulla (Albuquerque et al., During the predation event, O. cabrerai produced 2007). In addition, observations of predation attempts by high-pitched distress calls, which we recorded with an Leptophis on other hylid frogs, incluing Trachycephalus Olympus Tough Stylus© digital camera. The sound of the (Solé et al., 2010; Yeager et al., 2019) and Hypsiboas distress call was extracted and analysed in the software (Eversole et al., 2018) have been documented. PRAAT (Boersma, 2001). The distress call consisted of harmonic and unpulsed notes, with a dominant frequency of 7.56–80.14 kHz and a duration of 0.23–1.57 s (Fig. 3). To the best of our knowledge, this is the first 1 Unit for Integrative Zoology, Department of Evolutionary documented observation of L. ahaetulla feeding on Biology, University of Vienna, Althanstraße 14, A-1090 a species of Osteocephalus, in which a distress call Vienna, Austria was noted. These types of vocalizations have been 2 Department of Behavioral and Cognitive Biology, University of described in neotropical frogs and other amphibians (see Vienna, Althanstraße 14, A-1090 Vienna, Austria Leptodactylidae – Dorado-Rodrigues, 2012; Padial et * Corresponding author. E-mail: [email protected] al., 2006; Hylidae – Santana et al., 2013; Osteocephalus © 2021 by Herpetology Notes. Open Access by CC BY-NC-ND 4.0. taurinus – Campos et al., 2011) and are used by frogs 210 Sarah Chaloupka & Camilo Rodríguez

Figure 1. Leptophis ahaetulla grasping Osteocephalus cabrerai and turning it around before swallowing it head-first. (A) Snapshot from the original video. (B) Enhancement of the image in (A) to show the position and orientation of the participants. Red arrows point to the characteristic bright blue tibia/tarsus colouration of O. cabrerai. when attacked and grasped by predators (Bogert, 1960). behaviour enhances the foraging success of gape-limited Although the exact function of these calls remains predators like snakes, by reducing the swallowing insufficiently known, the most likely function is to alert duration and minimizing potential risks and resistance conspecifics of danger or to frighten predators (Wells, due to the appendages of the prey (Reimchen, 1991). 2007). Furthermore, our observation confirms previous findings regarding the “head-first” ingestion of prey byL. ahaetulla (Albuquerque et al., 2007). This prey-handling Predation by Leptophis ahaetulla on Osteocephalus cabrerai 211

Figure 2. Leptophis ahaetulla as it moves up onto higher branches in the tree where the altercation took place, revealing a body swollen from the ingested Osteocephalus cabrerai.

Acknowledgements. This event was observed in the natural INBS-0001; Labex CEBA ANR-10-LABX-25-01). This work reserve of Nouragues and we thank the Nouragues research field was funded by the Austrian Science Fund (FWF: W1262-B29). station (managed by Centre National de la Recherche Scientifique, We also thank Eva Ringler for additional financial support to the which benefits from “Investissement d’Avenir” grants managed first author. by Agence Nationale de la Recherche (AnaEE France ANR-11- 212 Sarah Chaloupka & Camilo Rodríguez

Figure 3. Distress call of Osteocephalus cabrerai. The call consists of harmonic and unpulsed notes, with a dominant frequency of 7.56–80.14 kHz and a duration of 0.23–1.57 s.

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Accepted by Anyelet Valencia-Aguilar