Authors: Johan Elmberg

Abstract: The movements within a population of individually marked male Common Frogs Rana remporaria were studied during the breeding season. No signs of territoriality were found. The population was characterised by a high degree of disorder and internal movements. Site fidelity within the pond occurred, but was rare. Some other features of the reproductive biology of the species are also described.

Authors: Trevor J. C. Beebee

Abstract: The tolerances of spawn and tadpoles of the natterjack toad to varying degrees of acidity have been investigated. The results show that:
l . Spawn and small tadpoles are more vulnerable than large tadpoles to low pH.
2. Total mortality of spawn occurs below pH 4.0 with the critical range for survival being between pH 4. 0-4. 5.
3. Growth rates of tadpoles are increasingly inhibited by pHs between 6.0 and 4.0 even in the presence of excess food.
4. It takes more than 24 hours for spawn to be killed by exposure to low pH (3. 5).
5. Healthy spawn is less vulnerable to acid damage than spawn containing large numbers of dead eggs at the outset .

Authors: Adrian Hailey and P. M. C. Davies

Abstract: This paper investigates the selection, ingestion and digestion of different sized goldfish by viperine water snakes Natrix maura. A previous study had suggested that sentinel foraging N. maura preferentially select medium sized fish to give the maximum rate of energy intake during ingestion. It was however found that snakes preferentially struck at the largest fish available in the range 1-20 per cent relative prey weight, even though these fish gave no advantage in ease of capture or rate of energy intake during ingestion or digestion. The advantage of this selection is shown to result from the schooling behaviour of fish and the low rates of capture during sentinel foraging. It was confirmed that snakes capture and attempt to ingest fish too large for them. A large fish provides an energy supply large in relation to the snake's requirements (covering about 60 days maintenance) compared to the small cost of handling before rejection. It would thus be better to handle all fish unless much too large, rather than rejecting those closer to the maximum and possibly making a mistake.

Authors: Carl H. Ernst and Jeffrey E. Lovich

Abstract: A study of growth of the shell and its scutes was conducted on 1 2 1 Platemys platycephala (Testudines: Chelidae). Straight-line carapace length, width and height increase at approximately the same rate as the straight-line plastron length, and are highly correlated to plastron length. Similar trends were noted for increases in bridge length and the width of both the anterior and posterior plastral lobes in relation to plastron length . Unequal growth rates occur in the vertebral scutes which may be correlated with development of carapacial curvitude. The femoral scute grows faster than the other six plastral scutes. Development of the middorsal groove, plastral concavity in males. and loss of the juvenile scute rugosities are also discussed.

Authors: C. P. Wheater

Abstract: The gut contents of 1 8 8 Common Toads from a range of sizes were examined and 1 898 prey items from 22 prey groups recorded. The use of combined gut contents (stomach and hind gut) is discussed in relation to the greater numbers of prey found iri the stomach and the differences in the proportions of prey in the different parts of the gut; hind gut contents having a larger proportion of hard bodied prey. Acari, adult Coleoptera, Formicidae and Collembola were found to be the most abundant prey groups, although differences were recorded with toad size. A positive linear relationship between prey and toad size was found. A nematode gut parasite (Cosmocerca ornata) was recorded and the degree of infection and the percentage incidence were found to increase with toad size.

Authors: Adrian Hailey  and p. M . C. Davies

Abstract: There was an ontogenetic change in the diet of the water snake Natrix maura, from earthworms and tadpoles in juvenile snakes to fish in adults. This was related to the absolute sizes of these prey types and to the scaling of encounter rates with snake size. Within each prey type relative prey weight RPW was independent of snake size, except for fish taken from drying pools (RPW inversely related to snake size). Overall, R PW increased with snake size (prey taken during normal foraging) or was independent of snake size (including fish from drying pools). Snakes handled fish too large for them to ingest. Multiple captures were common from drying pools, the fish being smaller than when a single fish was taken.
Foraging behaviour of wild N. maura could be described as exploratory activity and cruising (finding slowmoving or trapped prey during slow movement); sentinel predation (an extreme sit-and-wait strategy for catching fish); active pursuit and undirected 'fishing' (less commonly observed). Sentinel N. maura took up different positions in the water according to their size. Breathing took up 20 per cent of their time; those at the surface spent shorter intervals foraging and breathing than those with deeper perches. Strike rate was once per 7.4 minutes, capture success was low, 2 out of 1 24 strikes, neither ingested. The relationship between the different types of foraging used by N. maura and other natricine snakes, and their stimulus control, are discussed.

Authors: B. Banks And G. Lavericki

Abstract: A survey of the distribution of amphibians was carried out in Sunderland (Tyne and Wear). Five species were present in the area, but Triturus cristatus and T helveticus were uncommon. All the amphibian species were declining or apparently extinct in wild ponds. Garden pools were less common than in other parts of England that have already been surveyed, and as a result of the low density of ponds many had not been colonised by amphibians. There was an encouraging number of colonies that had been started by deliberate introduction however. Rana temporaria and T vulgaris were the only species that had colonised the ponds to any great extent . Both were found to be very susceptable to fish predation, and mechanisms for surviving in fish ponds are discussed. A n other danger was the destruction of garden ponds which was astonishingly common.

Authors: Dr. Zuhelrn . Mahmoud And Dla'a A . Eln Aeem

Abstract: The volume of blood in the common African toad (Bufo regularis) was determined by the use of radioactively labelled red blood cells (RBC-Cr5 1). Blood volume obtained = 6 . 24 ± 0. 1 7. Values are expressed as per cent of body weight. Females have higher hematocrit than males (P<0.02).

Authors: Armand J. De Ricqlés