The range sizes and habitat preferences of nine adult European grass snakes (Natrix natrix) were determined from radio-tracking data obtained within a landscape of mixed deciduous woodland and pastoral fields in southern England. These data were analysed using RANGES7v0.81 software. Concave polygons resulted in overall individual range size estimates that varied between 0.18-9.41 ha. However, for individuals that were radio-tracked for more than one season, annual range size estimates ranged between 1.29 ha and 3.56 ha and some snakes shifted their range between seasons. Grass snakes showed a strong preference for habitat boundaries and interfaces and an avoidance of woodland, and fields that were used for grazing. The attributes common to habitats that snakes preferred were a combination of basking site availability and a close proximity to relatively dense vegetation that offered potential protection from predators. The attributes common to habitats that snakes avoided were a lack of basking sites in woodland, and cover, in fields. Grass snakes selected banks as hibernation sites, the majority of which were within woodland.
The role of managed coniferous forest in the conservation of reptiles.
Habitat selection in adult and juvenile Bufo achalensis was studied at La Ciénaga Stream, Pampa de Achala, Central Argentina from December 1998 to October 2001. Habitat preference was evaluated by comparing the observed use of each habitat type with its availability. Juveniles were surveyed on 32 occasions between January 1999 and March 2001 using 13 permanent transects. The effect of cattle on larval survivorship was also evaluated. Most adult and juvenile B. achalensis occurred within 300 m of each side of the breeding site stream. No correlation was found between body size and distances moved. Juveniles and adults selected granite outcrops after the breeding season and avoided the heavily grazed areas. Adults also selected the stream and used tall tussock grassland in proportion to its availability. Juveniles used loose, flat, relatively small stones as shelters whilst adults used larger rocks. The presence of cattle at the breeding sites directly reduced larval survivorship by trampling, and indirectly through sediment deposition at the breeding sites resulting from increased stream bank erosion. The habitat preferences of B. achalensis suggest that long term cattle grazing also affects them adversely through deterioration of their transition habitat from tall tussock grassland to short sward. Future conservation management plans for B. achalensis must include the protection of the breeding sites and the surrounding terrestrial area if they are to be effective.
The diet of Smooth snakes (Coronelía austríaca) inhabiting lowland heath in southern England was studied over a nine -year period (2004-2012) by analysing 226 faecal samples obtained from 19 females and 41 males of varying age/size from juveniles to sexually mature adults. The main prey species belonged to the families Lacertidae (48%), Soricidae (32%) and Muridae (13%) with the remaining 7% comprising Anguidae (6%), Colubridae (0.5%) and Bufonidae (0.5%). Small mammals were absent from the diet of the smallest snakes but were a major component in the diet of large snakes. Lacertids were a major component of the diet of juvenile snakes whilst they formed a progressively smaller part of the diet of adult snakes. The data demonstrates a shift in diet, with increasing snake size, from Lacertids to small mammals. The highest number of small mammals was found in the diet during the early part of the activity period (April-Iune) with females apparently preying mainly upon Lacertids in late summer (August-October). A detailed understanding of the diet of C austríaca, and how it changes with increasing snake body size, may have implications for the conservation of the species in the UK. Management of heathland that damages the preferred habitat of small Lacertids, the main prey of the smallest juvenile snakes, is likely to have a negative impact on recruitment and, as a consequence, a negative impact on the survival of C. austríaca populations.
A population of vizcacheras frogs Leptodactylus bufonius was studied at a man-made pond in the north of Córdoba Province in central Argentina during December 2000 and 2001. Breeding females were larger than breeding males with both sexes attaining sexual maturity at two years of age and most living to a maximum age of four years. The sex ratio of the breeding population was approximately 1.2? : 1/. Although the numbers of eggs and tadpoles found in sealed nests was the same as the number of eggs found in the ovaries of unspawned females, between-year differences in egg production per female were found. Nests were constructed by males, at night, and then abandoned for at least 24 hours. Amplexus and spawning occurred within the nest. The nest was then vacated and the female sealed the nest aperture with wet mud. The minimum and maximum temperatures recorded inside sealed nests were less extreme than those recorded outside the nest.
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