Weißflanken-Dunkeltyrann Knipolegus hudsoni

Highly migratory flycatcher that breeds in central Argentina from around September through March, then disperses north to Bolivia and Paraguay, and occasionally wanders even farther. Male is glossy black with a silvery, black-tipped bill. He has a white on the underside of the wing that is usually hidden while perched. Female is brown and buff with white wingbars, cinnamon rump and tail base, and faint mottling on the breast. Very similar to White-winged Black-Tyrant; female is paler on the breast and belly, but males are virtually indistinguishable in the field. Inhabits stunted forest, scrub, and overgrown clearings.