Authors: Ignacio De La Riva

Authors: J. W. Arntzen And S. F. M. Teunis

Abstract: The population dynamics of the crested newt, Triturus cristatus. in a newly created aquatic habitat in a dune area in northwestem France was studied over a six year period. After a rapid colonization of the pond in year I, and a fast initial increase to reach 335 newts in year 5, the adult population size dropped dramatically to 16 in year 7. Variation in the adult population among years was largely due to variation in juvenile recruitment. In the longer term. the population stabilized at about 40 newts. Since the population has survived for five times the minimum generation time of the species, the colonization was judged to be a success. An estimated 50% of the juveniles joined the breeding population at age 2; those that did not breed by then spent the third year on land. The average annual survival rate for the juveniles was 0.22. For the adults survival was 0.49 and showed almost no fluctuations over time or with age. Given a short distance to disperse, the crested newt can be an opportunistic species.

Authors: Andrew S. Gardner And Sey Ad M. Farook

Authors: John Davenport And Jane F. Ward

Abstract: The appetite of saltmarsh diamondback terrapins (Malaclemys Terrapin) is extremely large (mean satiation ration on a diet of mussel flesh at 25ºC = 7.2% body weight), some 8- 10 times that of closely related freshwater emydid turtles. When held in sea water without access to fresh water the appetite of diamondbacks is gradually depressed, reaching (after 18 days in sea water) 22-54% of the average satiation ration recorded when fresh water is available. Between 20 and 35"C appetite in Malaclemys is stable (Q₁₀ = 1.1). Between 15 and 20ºC Q₁₀ = 20.7, indicating a shift to a hypometabolic state below 20ºC.

Authors: Jonathan S. Denton And Trevor J.C. Beebee

Abstract: We have investigated the refugia used by Bufo calamita and Bufo bufo throughout the year on heathland, sand dune and saltmarsh habitats in Britain. On the first two habitats, natterjacks mainly lived at depths of >20 cm in burrows of their own making and these burrows insulated animals very effectively against temperature fluctuations during the summer. In saltmarsh habitats natterjacks used a variety of refugia and at all sites common toads were found in mammalian burrows and under stones, logs and piles of leaf litter. Natterjacks at the saltmarsh site vacated areas following tidal inundation with no evidence of mortality attributable to this event. At the heathland site, male natterjacks adopted two distinct strategies for refugia use during the breeding season: commuters travelled to and from the ponds every night, returning before dawn to their summer burrows, while residents took up temporary abode near the ponds for the duration of the breeding season. On heaths and dunes natterjacks usually used the same burrows for hibernation that were used in the summer months, but buried themselves more deeply. Common toads also used similar sites to those occupied in summer, but often these were selected following an autumn move towards the breeding ponds. At the saltmarsh and other coastal sites in Cumbria, most natterjacks and all common toads hibernated under piles of stones or logs. or in the burrows of small mammals.

Authors: F. Wood And J. Wood

Abstract: Cayman Turtle Farm released 26,995 yearling and hatchling green sea turtles, Chelonia mydas, into the waters surrounding the Cayman Islands. between 1980 and 1991. Released turtles were the offspring of the farm's captive breeding colony. Tagged turtles were regularly recaptured and re-released locally and demonstrated growth rates of 3.0 kg/year. With turtles recaptured from other regions of the Caribbean, recapture rate for turtles released as yearlings was 4.1 %. 66% of the locally recaptured turtles were infected with cutaneous fibropapil lomas, a condition increasingly observed among turtle populations worldwide.

Authors: John Davenport, George H. Balazs, John V. Faithfull And Don A. Williamson

Abstract: A large stone-like object was collected from the rectum of a leatherback turtle beached at Midway Atoll. Hawaiian Islands. It consisted of biomineralized faecal material, the mineral being struvite (NH₄MgPO₄.6H₂O). Much material of anthropogenic origin (plastics in sheet and linear form, plus other packaging materials and monofilament nylon) was incorporated into the faecolith structure. It is hypothesized that the formation of struvite stems from the interaction of the leatherback's osmotic physiology with the metabolism of faecal bacteria. While the formation of the faecolith may be pathological, it could alternatively be an adaptive response to package garbage (whether natural or man-made).