Red squirrels do not hibernate and lay down stores of food to see them through periods when fresh food is not available. Where they are found in mixed broadleaf and coniferous woodland they have a source of food all year round, as pine seeds are present over the winter months. However, red squirrels have quite a varied diet which includes seeds, buds, flowers, leaves and fruit. They are known to take insects, fungi and birds' eggs. Red squirrels build nests, called dreys, from sticks and moss placed high in the branches. They produce two litters of three to four kittens a year, usually in March and July. The drey is often the first evidence of the presence of red squirrels in a wood. Other signs are chewed pine cone 'cores' (birds leave ragged remains), split hazel nut shells (dormice make a hole to extract the kernel), cut tree shoots and scattered droppings. Red squirrels can live for up to six years. They are chiefly active during the day and most of this time is spent foraging. Bad weather can seriously hinder this activity and, without food the squirrels can only survive for a few days.