often found in places such as gardens and sheds, and even prefer habitats such as old walls and stonewalls, derelict buildings and ruins that offer a variety of hiding and basking places. The synanthropic aspect appears to be more pronounced in northernmost parts of the range where they are dependent on human structures for food, warmth and hatching grounds. They avoid open plains and agricultural deserts. In the south their range seems to coincide with the borderline between deciduous broadleaf forests and Mediterranean shrublands, with the latter presumably too dry for the species. In the north their line of presence appears temperature-limited. Diet and predators Their main food source are rodents up to the size of rats (a 130 cm adult specimen has been reported to have overpowered a 200g rat) and other small mammals such as shrews and moles. They also eat birds as well as bird eggs and nestlings. They suffocate their prey by constriction, though harmless smaller mouthfuls may be eaten alive without constriction, or simply crushed on eating by jaws. Juveniles mainly eat lizards and arthropods, later small rodents. Other snakes and lizards are taken, but only found rarely in adult prey. Predators include badgers and other mustelids, foxes, wild boar (mainly by digging up and decimating hatches and newborns), hedgehogs, and various birds of prey (though there are reports of adults successfully standing their ground against feathered attackers). Juveniles may be eaten by smooth snakes and other reptilivorous snakes. Also a threat mainly to juveniles and hatches are domestic animals such as cats, dogs, and chickens, and even rats may be dangerous to inactive adult specimens in hibernation. In areas of concurrent distribution, they are also preyed upon by introduced North American raccoons and east Asian raccoon dogs. Behaviour The snakes are active by day. In the warmer months of the year, they come out in late afternoon or early morning. They are very good climbers capable of ascending even vertical, branchless tree trunks. The snakes have been observed at heights of and even in trees, and foraging in the roofs of buildings. Observed optimum temperature for activity in German populations is (Heimes 1988) and they are rarely recorded below or above , other observations for Ukrainian populations (Ščerbak et Ščerban 1980) put minimum activity temperature from and optimum to . Above around they try to avoid exposure to direct sunlight and cease activity with