O. G. Dely szerk.: Vertebrata Hungarica 21. (Budapest, 1982)

Ananjeva, N.B. ; Orlov, N.L.: Feeding behaviour of snakes 25-32. o.

of relatively large prey. This accounts for the specificity of many forms of ophidian behaviour, in this context, their feeding behavior. Common defensive and threating postures and movements as well as those of aggressiveness and reproduction have long been noted. Defence and attack responses, as interrelated components of the "triotroph system" (MANTEIFEL 1980) are extremely important for the understanding of different forms of feeding behaviour and "predator-prey" relationships. Snakes show a set of stereotyped movements and complex defence and attack responses. These responses are most characteristic of interspecific aggression and most apparent in reproductive behaviour (mating, male flighting, courtship) in which they appear ritualized. Rltuallzatlon (i.e., development of informative, signal function, LORENZ 1969, DEWSBURY 1981) along with a total or partial reduction of the primary locomotor function) is seen in a number of head and tongue movements, as well as in those of the body and tail. They can be either smooth or abrupt, dorsoventral or lateral. There are over 100 stereotyped movement patterns (CARPENTER & FERGUSON 1977), most of which appear to be trophic responses. Reference here is to the primary function of the movements, which are observed as ritualized pattern in other situations. Identical responses may occur in different behavioural situations. This paper deals with .entire complex as feeding behaviour, beginning with the search for prey to its killing and swallowing. The latter aspects seem particularly essential for the identification of trophic behaviour, which must not be confused with other behaviour, such as exploratory patterns. Strategies for feeding Most snakes hunt prey from ambush, which may be facilitated by colouration or body shape. The snake may also move towards the prey or may actively pursue It over a short distance. More often, snakes use combined strategies, as do Dendrelaphis. Achaetul

a and Oxybell

s, which hide in trees and attack It from above (BISWAS et al. 1977). Species of the genera Coluber, Psammophls

, and Spalerosophi

a pursue the prey over some distance. Batrachophages frequently engage in active pursuit of the prey. These snakes (

Nerodi

a, Natrlx, Cyclagre

s) move at 16 m for 10 sec. They also make abrupt thrasts of the head and follow the leaps of the frog, with open mouth until the teeth catch they prey. Ambush tactics are used by many Boidae, Viperidae (SHINE 1980, PIANKA 1981) and Crotatidae. After an unsuccessful ambush these snakes may active pursue or slowly scan the trail of the prey using olfactory cues. Luring is often employed in feeding. The well disguised body of the snake may give the impression of a branch on which a bird, a lizard or a mammal may "perch". Still more striking Is the imitative behaviour of the twig snake, Thelotornls kirtland

i (GOODMAN & GOODMAN 1976), which creates In African sunbirds an illusion of a fledgling, by inflating the anterior part of the body and elevating its head to display the pointed tip. It has been reported, that birds fly close the snake, facilitating its hunting. It remains uncertain, whether the birds approach the snake because its head simulates a fledgling. This seems doubtful, first, because brooding birds become restless and alarmed In the presence of a potenciál enemy and will "swoop down" on it attempting to distract it. Also, comparison of the snake head with the fledgling may be antropomorphic considering high resolution of avian vision. Tongue luring has been shown to be amployed in feeding behaviour In Ox

ybell

s (MOLE 1924, RABB 1972). Here, the tongue Is both the analyzer and the lure for small animals, wich mistake it for larval insect. However, an alternative hypothesis (KEISER 1975) holds, that prolonged extrusion of the tongue causes the prey to freeze rather than luring It. Prolonged olfactory contact Is also supposed to have a role in this display. Caudal luring is a common behaviour that has now been observed in juvenile Chondropython viridi

s (MURPHY et al. 1978), juvenile Boa constricto

r (RADCLIFFE et al. 1980), juvenile Vipera russell

i (HENDERSON 1970), adult Cerastes viper

a (HEATWOLE & DAVISON 1976), adult Cerastes viper

a (HEATWOLE & DAVISON 1976), adult Bothrops bllineatu

s (GREENE & CAMPBELL 1976), juvenile and adult Slst.rurus miliari

s (JACKSON & MARTIN 1980) and adult Acanthophls antarcticus (CARPENTER et al. 1980). Tail luring is most commonly employed by juveniles and is reinforced by a bright contrasting colouration of the tall tip. NEILL (1960) used this morphological feature to predict tail luring in several species; this prediction was subsequently confirmed (cf. Acanthophls antarcticu

s, CARPENTER et al. 1978; Chondro-Trimeresurua gramiqeua

. our data). Young Chondrophython viridis (ORLOV 1981) coils on a branch and elevates its brightly-colored caudal tip, undulating It while