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

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

the rest of the body remains immobile. Hyla arbore

a and Rana temporarl

a have been observed to attack the tip, apparently mistaking it for a prey object. Both frogs were Instantly seized and swallowed. However, the python showed different tactics when hunting Lacerta vlvlpar

a. It hooked its body over a branch, with the head and the tail hanging down. Neither head nor body moved, but the tail moved worm-like, horizontally, rather than vertically, as in the former situation. The lizard attempted to catch the tail and was captured and consumed. Not only has caudal luring now been documented so has the fact that snakes can discriminate between prey types and employ different luring patterns. The successful caudal luring In Trimeresurus gramineu

s seems to disagree with GREENE & CAMPBELL (1972) who feel that this movement is merely defensive and warning behaviour. Cta the other hand, we have observed lure-like caudal movement In terrestrial species (

Agklstrodon contortrix, A. blomhoffl. Vipera kaznakov

i. V. ammodytes transcaucaslana, V. lebetlna turanica. Bothrops schlegel

l, B. neuwled

l. Boa constrictor

), when those hunt rodents of different ages. These rodents do not respond to the caudal lure and the snakes therefore employ a different hunting strategy. Indeed, we are not convinced by the reported rodent responses to lure (HENDERSON 1980, CARPENTER et al. 1978). We are more In favour of the current view (GREENE & CAMPBELL 1972, HEATWOLE & DAVISON Í976, JACKSON & MARTIN 1980) that the wide-spread occurrence of tail luring In juveniles is basically due to their diet of frogs and lizards. This behaviour In adults is normally confined to species which show no ontogenetic differences In their feeding, but are batrachophages or saurophages as adults. Lizards and frogs are apparently highly sensitive to caudal luring, particularly insectivorous ones. This kind of lure seems inappropriate for most birds and mammals, the vision of which is capable of high resolution. Incidentally, a mouse may engage In aggressive or defensive movements in new surroundings, which can easily be erroneously understood as feeding responses to luring. Various hypotheses exist on the origin of the caudal lure. The most Interesting, as well as plausible is that expressed by RADCLIFFE| and co-suthors (RADCLIFFE et al. 1980) to the effect that tail movements In predators snakes result from displacement activity in a conflict situation due to the Incongruous purposes: to remain unnoticed and to pursue the prey. The comparable movement is caudal undulations in hunting cat. It would seem reasonable to assume that selection would favour movements attracting prey yet allowing the predator to keep out of danger. This type of trophic behaviour is obviously advantageous to more vulnerable juvenile animals. We have seen tail luring in juvenile Chondrop.ython viridi

s in the absence of prey, caudal luring Is also more frequently and more persistently employed by a hungry snake. In a review of defensive tall display of snakes and amphisbaens, GREENE (1973) concludes that rituallzation of primary movements either repels prey or attracts It. We have repeatedly observed such caudal movements In mating behaviour (involving fighting) of Vipera lebetlna turanic

a, V.l. obtusa, Echis multlsquamatus, Coluber rhodorhachls, Elaphe cllmacophor

a, E. quadrlvlrgata

. Important signals, widely employed in diverse behavioural situations, Including feeding, defensive and mating behaviour, apparently have comme» origin. They appear to be involved in different behavioural systems, due to the action of endo- and exogenic factors. This independence cm the original motivation context is known for displays arising as a result of displacement activity (DEWSBURY 1981). Social facilitation of feeding behaviour Social facilitation may play an Important role in feeding behaviour (DEWSBURY 1981). This phenomenon investigated largely In mammals, consists of Increased frequency of certain type of behaviour in the presence of other individuals. Such facts are known to physiologists as examples of mediated learning or of Imitation conditioned reflexes (MANTEIFEL 1980). In reptiles the socalled "social feeding" involving social facilitation and imitation was first observed in the iguana lizards Anolls carollnensls, Sceloporus cyanogeny

s and Dlpsosaurus dorsali

s (GREENBERG 1976). The phenomenon is generally easier to observe In experimental conditions when the animals are kept in a "group", within sight of another. We have first observed It in snakes. We have elicited feeding activity In eight Vipera kaznakov

i, which otherwise exhibited no feeding response when offered Mus musculus

. The effect was achieved by Installing a new snake already adapted to the experimental conditions and already feeding. The snake instantly responded to the presence of prey and showed feeding behaviour, I.e. head elevation, rapid tongue flicks. The conspeciflcs gradually began sensing the surroundings as indicated by Increased tongue flicks and also showed other signs of feeding arousal. The vipers become still more strongly stimulated when the newly-