0 the white-crowned sparrow (zonotrichia leucophrys) is a medium-sized sparrow native to north america .
1 adults are {convert|18|cm|in|0|abbr=on} long and have black and white stripes on their head , a grey face , brown streaked upper parts and a long tail .
2  the wings are brown with bars and the underparts are grey .
3  their bill is pink or yellow .
4  they are similar in appearance to the white-throated sparrow but do not have the white throat markings .
5 there are five currently recognized subspecies of white-crowned sparrow (pugetensis , gambelii , nuttalli , oriantha , and leucophrys), varying in migratory  behaviour and breeding habitat .
6  the nuttall's subspecies are permanent residents in california , while the gambel's subspecies may migrate as far as the arctic circle during the summer breeding season .
7  northern birds migrate to the southern united states .
8 their breeding habitat is brushy areas across northern canada and the western united states .
9 white-crowned sparrow is a very rare vagrant to western europe .
10  it has been recorded from england , scotland , ireland , and norway .
11 these birds forage on the ground or in low vegetation , but sometimes make short flights to catch flying insects .
12  they mainly eat seeds , other plant parts and insects .
13  in winter , they often forage in flocks .
14 white-crowned sparrows nest either low in bushes or on the ground under shrubs and lay 35 brown-marked grey or greenish-blue eggs .
15 the white-crowned sparrow is known for its natural alertness mechanism , which allows it to stay awake for up to two weeks during migration .
16  this effect has been studied for possible human applications , such as shift-work drowsiness or truck driving .
