A summer visitor, arriving in March and migrating south again during September. The male has a distinctive diagonal black band on its upper wing surface and streaking on the belly. Females are much harder to tell apart, but there are slight differences in the wings. The Montagu's has a smaller chord, especially near the base, and this makes the tip appear more pointed; moreover, if you manage to get a close enough look - or have your camera handy - the Montagu's has four "fingers" while the Hen has five.
