The Atherton Tablelands is a high flat plateau, 2400 ft elevation, that extends across eastern Queensland near Cairns. A series of volcanos spread basalt lava across this area, and it is now fertile agricultural land. We’d been cruising the back roads looking for birds. Brolga and Saurus Cranes fed in many pastures, and several small flocks of Red-tailed Black Cockatoos dashed from one tree to the next. Around a corner, a Black-shouldered Kite hunting from a fence post made us stop.
There it sat, white with a dark eyebrow, black shoulder patch, and gray along its back. The feet and legs were bright yellow, and its black talons were visible. An adult Black-shouldered Kite looked back and forth, then leaned forward so its red eyes stared down at the grass. I willed it to pounce on a grasshopper or mouse, but it just sat there, teasing us with its beauty.
This bird is in the genus Elanus, and four species have been classified worldwide in this genus. Sitting on a post, they all look virtually identical, and I don’t know if I could tell them apart. When they fly, the black and white pattern on their underwing varies and is distinctive. The Black-shouldered is the only one in this part of Australia. The letter-winged occurs in central Australia, a more arid part of the continent. One is the White-tailed, which is in the Western Hemisphere and does come up into Washington State. The Black-winged live in Africa and southern Asia. I’ve never seen the Letter-winged, but I watched the other three species fly. They are graceful, with long, narrow wings that allow them to move quickly through the air and hover above a field, looking for prey. To me, they are one of the most elegant birds.
I hoped we might find this bird on our trip, for I’d been thinking a lot about evolution and the southern continents. This species is one of four called super-species by taxonomists. Ernst Mayer, a prominent evolutionary biologist, coined that term to denote closely related species that generally are allopatric. They show the case where natural selection and separation have divided an ancestral species into more than one. It is evolution happening, which is always going on, but here, because they look so similar, we are seeing it more clearly. At some point in the past, the ancestors of these species made it across all the southern continents. This bird model, this shape, size, and behavior, works well, and in time, the ancestor adapted to the unique conditions in each place, evolving into these species.
Our kite turned, facing away, opened its wings, and disappeared across the field as a ballerina might dance across the stage.
