Siphlophis Compressus (Serpentes: Dipsadidae) Scavenging on a Road-Killed Polychrus Marmoratus (Sauria: Polychrotidae)
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Herpetology Notes, volume 10: 267-270 (2017) (published online on 29 May 2017) Siphlophis compressus (Serpentes: Dipsadidae) scavenging on a road-killed Polychrus marmoratus (Sauria: Polychrotidae) Mirco Solé* and Iuri R. Dias Roads and traffic have severe ecological impacts on represented (Gomes et al., 2013). Arboreal snakes wildlife. While direct loss of habitat and changes in the and lizards are much less susceptible to death on hydrology are problems related to road construction, roads, but even strictly arboreal species may have once a road starts being used by automobiles other to move on the ground periodically in order to impacts arise. These include isolation of populations, proceed with egg-laying or to move between forested facilitation of the dispersal of pest species, and the areas in fragmented landscapes. In these cases they effect of run-off from roads on aquatic communities may need to cross a road, and during this high-risk (Spellerberg, 1998). However, the most conspicuous endeavour fast-moving lizards, like the members of ecological impact is animal casualties. Approximately the genus Enyalius, may be less likely to get run over five million reptiles and frogs are road-killed every than slow-moving lizards, such as members of the year in Australia (Forman et al., 2003). genus Polychrus. Several studies have reported on While solid data regarding the construction and road-killed Polychrus acutirostris (Carvalho et al., short- vs. long-term effects of roads are available for 2014; Braz and França, 2016). The genus Polychrus several temperate ecosystems in Europe and North contains eight species distributed from Honduras to America (Spellerberg, 1998), numbers are not well South America, where they can be found on both known for the Neotropics (D’Anunciação et al., 2013). sides of the Andes (Avila-Pires, 1995; Murphy et On the one hand, greater and more diverse numbers of al., 2017). The species within the genus with the scavenger species may be able to retrieve road-kills largest distribution is Polychrus marmoratus, which before they are detected by researchers (Antworth et can be found in Guyana, French Guiana, Suriname, al., 2005; Korner-Nievergelt et al., 2015), and on the Venezuela, Colombia, Ecuador, Peru, Paraguay, and other some physiological requirements that account Brazil (Hoogmoed, 1973). for large numbers of road-killed snakes in temperate On 16 November 2016 at 2350 h we encountered a regions may play only a minor role in tropical female Siphlophis compressus (Daudin, 1803) trying environments, where less time of the day and night is to swallow an already dead Polychrus marmoratus spent on thermoregulation (Bovo et al., 2012). (Linnaeus, 1758) in the middle of the BA-262 road In most studies on road-killed vertebrates carried between Uruçuca and Ilhéus (14.6184° S, 39.2592° out in Brazil, reptiles rank in the third position when W; WGS84), southern Bahia, Brazil (Fig. 1). The considering the number of casualties, after birds snake did not appear to be disturbed by our arrival and mammals (Gomes et al., 2013; Carvalho et al., or continued presence and continued swallowing her 2015; Deffaci et al., 2016). Most of these reptiles prey. We followed the event for 10 min but as the are terrestrial snakes like Boa constrictor, but large snake was swallowing a very large prey and as cars terrestrial lizards like Tupinambis merianae are also were driving past at full speed due to low amounts of traffic at the late hour, we decided to place the snake and the half-engulfed lizard inside a snakebag. After arriving in Ilhéus we confirmed that the snake had managed to completely swallow her prey. Graduate Program in Zoology, Universidade Estadual de Santa Cruz, Rodovia Jorge Amado, km 16, 45662-900 Ilhéus, We kept the snake for several weeks in a terrarium, Bahia, Brazil where she refused any kind of food offered * Corresponding author. E-mail: [email protected] (lizards). On 28 December 2016 she laid five eggs 268 Mirco Solé & Iuri R. Dias Figure 1. Siphlophis compressus (MZUESC 17583) swallowing a Polychrus marmoratus on the BA-262 road, near Ilhéus, Bahia, Brazil. (Fig. 2), measuring from 27.6–30.2 mm in length, reported to lay between 3 and 12 eggs (Martins and 13.1–13.8 mm in width, and weighing 3.19–3.31 Oliveira, 1998; Gaiarsa et al., 2013). The clutch of g. After oviposition she continued rejecting offered five eggs reported here is close to the mean number Hemidactylus mabouia and only consumed one of 6.2 eggs reported by Gaiarsa et al. (2013). Anolis fuscoauratus. On 13 February 2017 the There are several ways to explain how the two snake was brought to the herpetological collection arboreal reptiles made their way onto a road, based of Universidade Estadual de Santa Cruz where it on the circumstances of the encounter. The lizard’s was euthanized, measured (snout–vent length 930 cloacal region appeared everted and we presume that mm, tail length 281 mm, total length 1211 mm) and this was the effect of having been run over by a car accessioned into the collection (MZUESC 17583). before the snake encountered it. The eversion could The genus Siphlophis is composed of seven mostly perhaps be the result of constriction during a predation arboreal species, which can be found in South and attempt by a snake, but the musculature of the slender Central America. Siphlophis compressus ranges from S. compressus does not appear to be strong enough to Costa Rica to Rio de Janeiro State in southeastern cause the required pressure. In terms of the encounter Brazil (Guedes et al., 2011). It is an arboreal and itself, we consider three possible scenarios for how nocturnal snake that has been reported to prey on the snake found the lizard. In one scenario the injured a lizard of the genus Tropidurus (Withworth et al., lizard continued to move, and its vigorous movement 2011) and on an Iguana iguana (Mollo Neto et al., might have attracted the snake as it perched on a 2013). Prudente et al. (1998) suggested that lizards nearby tree or bush. In a second scenario, the snake with diurnal activity may be apprehended by S. could have been attracted by the chemical cues from compressus while asleep on branches at night. This the everted cloaca of the injured lizard. In a third, but snake has also been reported to occasionally prey on unlikely scenario, the snake coincidentally crossed anurans, snakes, mammals, and lizard eggs (Guedes the road at the very same place where the lizard had et al., 2011). Individuals of S. compressus have been been injured or killed and encountered it by chance. Siphlophis compressus scavenging on a road-killed Polychrus marmoratus 269 Figure 2. Siphlophis compressus (MZUESC 17583) during egg laying in captivity in Ilhéus, Bahia, Brazil. Scavenging on carcasses has mostly been reported Acknowledgments. We acknowledge CNPq for scholarships for terrestrial snakes. Reports have included that of (404417/2015-9, 304999/2015-6, 150372/2016–7) and funding a Northern Pacific Rattlesnake (Crotalus oreganus (449930/2014-9). The collecting permit number 8385-1 was issued by SISBIO/ICMBIO/MMA. We thank Tadeu Teixeira oreganus) trying to swallow a road-killed Deer Medeiros for measuring the snake. Mouse (Peromyscus maniculatus) (Dornburg and Weaver, 2009). According to DeVault and Krochmal References (2002), scavenging by snakes may be far more common than currently acknowledged. Some species, Antworth, R.L., Pike, D.A., Stevens, E.E. (2005): Hit and run: such as Cottonmouths (Agkistrodon piscivorus), may effects of scavenging on estimates of roadkilled vertebrates. Southeastern Naturalist 4: 647–656. even obtain the majority of their food in this way Avila-Pires, T.C.S. (1995): Lizards of Brazilian Amazonia (Wharton, 1966). Studies on the Brown Treesnake (Reptilia: Squamata). Zoologische Verhandelingen 299: (Boiga irregularis) have shown that these snakes 1–706. are able to locate carrion using only olfactory cues, Bovo, R.P., Marques, O.A.V., Andrade, D.V. (2012): When whereas live prey is found most effectively by a basking is not an option: thermoregulation of a viperid snake combination of visual and chemical cues (Shivik et endemic to a small island in the South Atlantic of Brazil. al., 2000). Unfortunately, too little is known about Copeia 2012: 408–418. Braz, V.S., França, F.G.R. 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