Northern House Martin

Upperparts are bluish-black with the blue metallic gloss. The white color on the rump is more extensive than on urbica. All upper tail coverts are white. The white rump and upper tail covert feathers very rare have dark shafts. The throat, breast, flanks and undertail are white sometimes brownish-grey tinged. The axillaries are brown-grey. The depth of the tail fork is much less than in urbica.