Reptiles and amphibians are generally considered to be cold blooded but this is not strictly true. That said, they do not have the same mechanism for controlling their body temperature as mammals and need to use external sources of heat, usually the sun, to warm themselves and use water to cool down if they become too hot. When cool they are lethargic and inactive, when warm they can move very quickly, even snakes that have no legs!
Lizards like to warm themselves on tin sheets and other human materials that absorb heat easily
All the animals in this group are insectivorous and some, the snakes, also feed on larger prey. Grass snakes, for example, are very fond of frogs! As a result of their diet all of these creatures spend their life on primarily on land. It is not true that amphibians only live in water; they enter water, usually still water in ponds, to breed. They also use water to cool down in hot weather (see above) and grass snakes can also be seen hunting in water for food.
Why are all six species of reptiles found in Dorset? Mainly because the Dorset heath is the ideal habitat for them. The sandy soil is perfect for breeding and there is an ample food supply. The limestone cliffs of the Purbeck coast are also good places for reptiles but they are difficult to find there as much of their range is in somewhat inaccessible places. Obviously Dorset's warm, southerly position also helps.
Amphibians can be more difficult. The best time to see newts is in spring when they are in water to breed. The rest of the year they are somewhat elusive. Frogs and toads are more usually seen in gardens than in the wild these days.
In general, all of these species are declining in Dorset (and throughout the British Isles), primarily because of habitat loss and fragmentation of breeding colonies leading to the weakening of gene pools. The heaths are prone to human disturbance through dog walking, mountain bike riding and purposely or neglectfully started fires. The rapidly declining population of insects is not helping their cause either. Some species are said to be well under half of the population levels of 50 years or so ago. Much thought and conservation effort is going in to try and reverse these trends.
There is no single place to see all of the creatures, each has its own unique niche, but by far the best place I know to see a number of them is the Dorset Wildlife Trust reserve at Higher Hyde Heath. Joining the Wednesday morning guided walk at Arne is also a good way to get familiar with some of these species.
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