Winter is always a hard time for our terrestrial wildlife.

The cold conditions mean that unless an animal has some way of heating itself up using an internal mechanism then it is going to be impossible to survive in an active form through the winter.

There are only two groups of animals that have managed this trick of internal heating and they are the mammals and some birds.

The rest have to either fly south to find warmer weather on the continent of Africa or, as the majority do, find a place as safe as possible and hide out the winter in a dormant state.

Most invertebrates choose to spend the winter in a dormant stage of their life cycle such as an egg or as a chrysalis.

There are a few exceptions, such as the ever-present woodlice that seem to be able to ride out the worst of the winter by hiding in small huddles deep beneath a fallen log but still remain active feeding and fleeing if necessary from any would-be predators.

Amphibians take to the bottoms of pools where the surface will freeze, but the temperature of the water will never fall below freezing at the bottom. Reptiles take to deep burrows where the thickness of the ground acts as insulating blanket to the cold.

Through the action of their muscles, mammals and some birds can generate a body temperature higher than their surroundings.

This increase in body heat comes at a price, though, as it is produced at the expense of energy.

This energy is obtained from food but, during the winter, much of the food, plant or animal material these animals have had to depend on during the rest of the year will itself have taken refuge from the cold weather and is very hard to find.

Hence, even among the bird and mammal populations, it is only a select few that have evolved to remain active and not hibernate or migrate throughout the winter.

For the animals that do remain active through the winter months, one of the key survival techniques seems to revolve around becoming a real generalist when it comes to food.

The ability to use initiative and intelligence to exploit new foods as and when they become available is also a real advantage. These are skills demonstrated by some of our most prominent and visible animals.

Foxes, badgers and many of our other larger animals are more likely to be encountered, as they become even bolder in their exploitation of our urban fringes. Among others, birds like the green woodpecker become more and more frequent visitors to bird tables.