Is it ensure, insure, or assure?
any of several species of small birds, named for building a domed nest with a side entrance, especially Seiurus aurocapillus, a wood warbler (family Parulidae, order Passeriformes) of North America east of the Rockies; it winters south to Colombia. Brownish-olive above, with a streaked breast, white eye ring, and black-edged orange crown, the bird looks like a small thrush. Its song, "tee-cher," is repeated with increasing intensity in dank woods. The ovenbird walks, unlike most other wood warblers, which hop. Its nest is a dome of grass placed on the ground