Tree Sparrows are fairly easy to separate from House Sparrows once you have 'got your eye in'. Both male and female Tree Sparrows are of similar appearance. Tree Sparrows have a characteristic warm red-brown crown, white patches to the sides of the head and a small black cheek patch. Juvenile birds are similar in appearance to the adults but are duller in colour and have dark rather than white cheeks.
The Tree Sparrow is a red-listed species of conservation concern, numbers having crashed since the 1970s. They will take readily to nest boxes and it is suggested that two or more sets of boxes are provided so that birds can set up colonies. The BTO Nest Box Guide by Chris du Feu has more details.