Herpetology Notes, volume 8: 231-233 (2015) (published online on 19 April 2015)

Predation attempts on birds by the snake Philodryas olfersii prevented by mobbing mockingbirds

Ivan Sazima

The Neotropical dipsadid Philodryas olfersii bird feeder that provided peeled bananas. Both fruits (Lichtenstein 1823) is a venomous, predominantly were sought by several passerine birds throughout the green, medium-sized snake that may attain about 100 day (Sazima and Marques, 2007). At this treelet, a P. cm SVL (snout-vent length). It dwells in forested olfersii individual was observed successfully preying areas and forest edges in southeastern South America, on passerine birds on three occasions from January forages both in vegetation and on the ground, and preys to March 2006 (Sazima and Marques, 2007). The on diverse vertebrates including birds (Hartmann and interactions between the snake and the birds reported Marques, 2005; Arredondo, 2011). Its wide foraging herein were observed on 14 January and 21 December tactics include choosing a profitable hunting spot to 2007 and 27 November 2011 (austral summer), around ambush prey (Sazima and Marques, 2007). While midday. The observations were made with bare eyes preying on birds, P. olfersii may be mobbed by a variety and through a 70-300 mm telephoto lens mounted on of bird assemblages, including the chalk-browed a camera, from a distance of 1-3 m. Voucher digital mockingbird, Mimus saturninus (Lichtenstein 1823), photographs of the snake both in ambush and retreat, a very active mobber (Sazima and Marques, 2007). as well as of the mobbing birds, are housed on file at Mobbing is a behaviour displayed by potential preys the Museu de Zoologia da Universidade Estadual de in presence of a predator, by which the prey attempt Campinas (ZUEC). to distract, confound, or physically attack the predator The following description is based on the most (Curio, 1978; Francis et al., 1989; Sordahl, 1990). extended of the three mobbing episodes (27 November Mobbing birds utter alarm calls, display conspicuous 2011). The snake apparently reached the fruiting visual signals, approaches or follow the predator treelet undetected by any bird and when first mobbed closely and thus, may put themselves in danger (Curio, by the mockingbirds (1104h) it was already coiled, 1978; Sordahl, 1990; Matheus et al., 1996; Motta-Jr., lying in ambush (Fig. 1A). The mockingbird group 2007). Herein I report on predation attempts on birds that mobbed the snake was composed of two adults by P. olfersii thwarted by a group of chalk-browed and three juveniles, all of them uttering short staccato mockingbirds, Mimus saturninus. alarm calls and flashing their wings (Fig. 1B). The The predation attempts by P. olfersii hindered by birds approached the snake closely from above and mockingbirds were recorded in a backyard (-22.826819 below, at times within its striking range (Fig. 1A). The S, -47.071594 W, 620 m a.s.l.) in the suburban area of snake seemed disturbed by the mobbing group, partly Campinas, São Paulo, South-eastern Brazil. The site uncoiling and redirecting its head to different position. had several trees and shrubs, including a Malphigia It struck at the nearest mobbers twice with no success. emarginata treelet that bore small red berries and a While the mockingbirds mobbed the snake, a couple of thrushes (Turdus leucomelas) and a hornero (Furnarius rufus) joined the mobbing group and uttered alarm calls. After about 30 min (1137h), the snake uncoiled and began to move on the treelet (Fig. 1B) closely followed by the mockingbirds. The two adults pecked Museu de Zoologia, Universidade Estadual de Campinas, at its tail at least 5-6 times each, which caused the 13083-970 Campinas, São Paulo, Brazil snake to move faster and eventually it left the treelet Corresponding author email: [email protected] 232 Ivan Sazima

Figure 1. The colubrid snake Philodryas olfersii mobbed by the mockingbird Mimus saturninus in South-eastern Brazil. A) The snake lying in ambush (s) is detected by a juvenile bird (jb) that approaches from below, uttering alarm calls and flashing wings. B) The retreating snake is approached by a juvenile bird (jb) from above. The birds flashed wings and uttered alarm calls until the predator was out of sight. Prevented predation attempts on birds by the snake Philodryas olfersii 233 and retreated to a dense hedge at 1202h, from where it References left the backyard. Thus, the mobbing lasted about 1h Arredondo, J.C. (2011): Revisão taxonômica do complexo and caused the snake to leave its hunting spot. Philodryas olfersii (Lichtenstein 1823) (Serpentes: The other two mobbing episodes differed in that the Dipsadidae). Unpublished PhD dissertation, Universidade de snake was detected by the mockingbirds while still São Paulo, São Paulo, 269 pp. moving on the fruiting treelet, likely searching for a Curio, E. (1978): The adaptive significance of avian mobbing spot to lie in ambush. Again, adult birds pecked at the I. Teleonomic hypotheses and predictions. Zeitschrift für snake’s tail 2-3 times while mobbing. In both episodes, Tierpsychologie 48: 175–183. Francis, A.M., Hailman, J. P., Woolfenden, G.E. (1989): Mobbing the snake did not coil and left the backyard in about by Florida scrub jays: behaviour, sexual asymmetry, role of 10 min. helpers and ontogeny. Animal Behaviour 38: 795–816. On 04 December 2014, with no mockingbirds in sight, Gwynne, J.A., Ridgely, R.S., Tudor, G., Argel, M. (2010): Aves another P. olfersii individual successfully preyed on a do Brasil. Volume 1. Pantanal e Cerrado. São Paulo, Editora small passerine, the bananaquit (Coereba flaveola) on Horizonte. the same treelet at 1135h. Hartmann, P.A., Marques, O.A.V. (2005): Diet and habitat use In the case of P. olfersii and mockingbirds described of two sympatric species of Philodryas (Colubridae), in south Brazil. Amphibia-Reptilia 26: 25–31. herein, mobbing clearly decreased the snake’s Matheus, J.C., Wittmann, U., Olaf, J., Leutfeld, M., Schuchmann, hunting success, as predicted by Curio (1978). K-L. (1996): Reactions of birds to nestling predation by a When mockingbirds were absent or the snake went snake. Ornitologia Neotropical 7: 163–164. undetected, it successfully preyed on passerine birds at Motta-Junior, J.C. (2007): Ferruginous pygmy-owl (Glaucidium the study site (present paper). The failure of P. olfersii brasilianum) predation on a mobbing fork-tailed Flycatcher to capture a bird prey, caused by a mobbing group (Tyrannus savana) in south-east Brazil. Biota Neotropica 7: of mockingbirds, is supported by the five episodes 321–324. recorded so far (Sazima and Marques, 2007; present Sazima, I., Marques, O.A.V. (2007): A reliable customer: hunting site fidelity by an actively foraging neotropical colubrid snake. paper). As the snake was mobbed by a bird species Herpetological Bulletin 99: 36–38. that form family groups (Gwynne et al., 2010), three Sordahl, T.A. (1990): The risk of avian mobbing and distraction functions suggested by Curio (1978) for mobbing, behavior: an anecdotal review. Wilson Bulletin 102: 349–352. namely “alerting others”, “move on hypothesis”, and “cultural transmission hypothesis” seem to be at work concurrently in this record of predation attempts by P. olfersii.

Acknowledgements. I thank Marlies Sazima for loving support in the field and at home; Cristina F. da Rosa for pointing to me one of the episodes; Cristiano de Campos Nogueira for the thoughtful review; the CNPq for earlier financial support.

Accepted by Christoph Liedtke