The call of the variable sunbird (Cinnyris venustus), tew-tew-tew-tew-tew, is a common sound in equatorial Africa. These flashy little avians perch in the highest branches of the trees and are not shy in announcing their presence.
The male, shown here, is brilliant. His blue-green "metallic" head and nape is contrasted by a yellow belly.
The needle-like curved beak of the sunbird is perfect for extracting nectar from flowers, as is its tubular tongue.
I spotted this one enjoying the sprinkler in the yard of our lodge, just outside Arusha, Tanzania.