The Eurasian blue tit (Cyanistes caeruleus or Parus caeruleus) is easily recognisable by its blue and yellow plumage. Sexes are similar, although the male is usually brighter. It builds its nest from moss, wool, hair or feathers, often in a hole in a wall, tree, gatepost or a nesting box. Blue tits forage for food in the tree canopy, although they do spend some time on the ground searching for food, especially in the winter. Males are generally monogamous although some have been recorded breeding with two females. Blue tits range throughout Europe (widespread in the UK with around 3 million pairs), Asia and North West Africa. In the time when 'the milkman' delivered bottles of milk to doorsteps, Blue tits were often photographed removing the caps of milk bottles and drinking from the bottle. This was to get at the cream at the top of the bottle which was digestible and very energy rich. With the introduction of semi-skinned and fat free milk and with the decrease of doorstep milk deliveries, the activity has become a part of blue tit folklore.