why are there not many reptiles in the Arctic region ?

If you go to the Arctic, you are unlikely to meet any snakes there. Do you know Why? It is because reptiles have not adapted to the polar conditions. Reptiles are cold blooded animals which mean that they do not produce their own heat. Instead, they rely on heat sources in the environment. In frigid settings, 'cold-blooded' animals like snakes and frogs simply never warm up- which is why no reptile has evolved to survive the rigors of the Arctic climate.

However, during the brief summer, viviparous lizards, slow worms, grass snakes and garter snakes can be seen in areas where there is no permanent layer of frost underneath the surface of the soil. Once winter sets in, they go into hibernation underground, and disappear for the rest of the year.