Field observations on the predation of the caecilian amphibian, genus Ichthyophis (Fitzinger, 1826), by the red-tailed pipe snake Cylindrophis ruffus (Laurenti, 1768)

The red-tailed pipe snake Cylindrophis ruffus inhabits humid habitats in lowland areas in southeast Asia (e.g. Smith, 1943; Manthey and Grossmann, 1997). It is well adapted to burrowing in loose soils (Smith, 1914; Taylor, 1965; Greene, 1983; pers. obs.). Given its phylogenetic position, anatomy, and behaviour, the diet and feeding biology of pipe snakes is of special interest in studies of the evolution of feeding on large prey by caenophidian snakes (see Greene, 1983; Cundall, 1995; Cundall and Greene, 2000) because “Cylindrophismight in fact come closest to themode of life expected in the earliest snakes” (Rieppel, 1978: 24). From the dissection of museum specimens and observations of laboratory maintained animals, it is known that Cylindrophis consume relatively large and elongate prey items such as snakes and eels (e.g. Smith, 1914; Saint Girons, 1972; Cox et al., 1998; Pauwels et al., 2000) and caecilians (Greene, 1983). However, Ž eld observations on feeding behaviour have apparently not been reported. Caecilians are limbless and snakelike amphibians distributed in moist tropical environments of the Old and New World. Most adult caecilians are terrestrial and fossorial, living within the soil. Due to their secretive habits, little information is available on the ecology of caecilians, including their predator-prey relationships. Although it is known from museum specimens that snakes prey on caecilians (e.g. Boulenger, 1913; Taylor, 1968), reports of Ž eld observations are extremely rare. Burger (1997) published a Ž eld record of a coral snakeMicrurus multifasciatus hertwigi preying on an adultGymnopis multiplicata in Costa Rica, and Grossmann and Schafer (2000) observed the predation by a Malayan krait, Bungarus candidus, on Ichthyophis sp. Here we report two Ž eld observations of cylindrophiid snakes feeding on ichthyophiidcaecilians. During a survey on the diversity of amphibians and reptiles in an agricultural landscape of the Mekong valley (north-eastern Thailand, Ubon Ratchathani Province, Khemmarat District) Cylindrophis ruffuswas commonly recorded near brooks, ponds, pools and many other humid habitats. On 4 June 2001, the perimeter of a large Ž shpond was studied (N 16±03:0940, E 105±01:7810, 170 m a.s.l.). A subadult C. ruffus (360 mm total length, 49.6 g) was found about 15 cm deep in loose sandy soil. Immediately upon being