Eurasian Tree Sparrow
Passer montanus

The Eurasian Tree Sparrow is found across Europe and Asia - in the east, it is a common town bird, while in the west, the House Sparrow takes over the urban role and the the Tree Sparrow is a bird of open farmland. They are slightly smaller than House Sparrows at 12.5 - 14 cm in length and can be told apart by the head markings - the Tree Sparrow having a chestnut head, white cheeks with a dark patch, while the House has a grey crown and cheeks. They occur in flocks, often very large and are generally seed eaters, although urban birds will adapt to a range of food types.
 

1: Ueno Park, Tokyo, 17/05/2012.