Grey Crowned Crane

It comes down to a single anatomical feature — the hind toe, or hallux. In the two crowned cranes (the grey crowned crane and the black crowned crane), the hallux is long and set low on the foot, so it can wrap around and grip a branch, giving the bird a functional perching foot. In all the other 13 crane species the hallux is short and raised, an adaptation to walking and running on open ground, and those cranes cannot perch and roost only on the ground or in shallow water. The crowned cranes are considered the most ancient living lineage of cranes, and the perching hallux is thought to be a primitive trait retained from a time before cranes became fully committed to open wetlands and grasslands. Roosting in trees gives crowned cranes a safer night's sleep away from jackals, hyenas, and other ground predators.

The "crown" is a dense tuft of stiff, wiry, bristle-like feathers (modified filoplumes), pale gold to straw-coloured with dark tips, that project upward and back from the crown and nape of the head. It is present in both sexes. The birds can raise it fully into a spiky halo or flatten it, and they manipulate it during their many social and courtship displays, along with head-bobbing, bowing, and inflating the bright red throat sac. A well-developed, clean, symmetrical crown is likely a signal of a bird's health and condition to potential mates and rivals. The crown is also, unfortunately, part of why the bird is trapped — its striking appearance makes it desirable as an ornamental captive.

Its numbers have collapsed by around 80 percent in three decades, and it was uplisted to Endangered in 2012. The two biggest pressures are habitat loss and capture. The shallow marshes and seasonally flooded grasslands the cranes need for feeding and, critically, for nesting are being drained, dammed, overgrazed, burned, and converted to crops across East Africa at high speed. At the same time, grey crowned cranes are caught from the wild in large numbers, both as chicks taken from nests and as adults lured and trapped, to be sold as garden ornaments, status symbols, and for the international exotic-bird trade, and for use in traditional practices. Pesticide poisoning, powerline collisions, and the disturbance or destruction of nests in farmed wetlands add to the toll. Uganda, where the bird is a national emblem and appears on the flag and coat of arms, has lost a large part of its crane population.

Yes, and cranes in general are famous for it, but crowned cranes are especially enthusiastic and dance throughout the year rather than only during pair formation. A dancing crane bows deeply, leaps into the air with its wings partly spread, runs in short bursts, shakes its head, and picks up and throws sticks, grass, or feathers. Pairs dance together to strengthen their bond, unpaired birds dance to attract and assess mates, and whole flocks may dance in a kind of social contagion. Even young chicks a few days old will bow and jump. Researchers think the behaviour serves multiple purposes at once — synchronising a pair, advertising fitness, relieving tension and aggression, and coordinating a flock — and that its year-round frequency reflects how socially complex these birds are.