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Black Falcon

The Black Falcon (Falco subniger) is a medium-large falcon that is endemic to Australia. It can be found in all mainland states and territories and yet is regarded as Australia's most under-studied falcon.

Description

The information in this section is based on recent descriptions by several authors (notably, Debus & Davies 2012, Debus & Olsen 2011, Morcombe 2002 and Birds in Backyards n.d.)

Size (adult, beak to tail): 45 – 56 cm (average 50 cm), tail makes up about half the length. Note: Females are larger than males - this is a form of sexual dimorphism.

Average weight: 833 g (female) 582 g (male).

Wing span: 95 –115 cm.

Colouration is uniform dark brown to sooty black; juveniles are generally darker than adults; underwing feathers are two-tone (flight feathers slightly paler); adults may have an evident dark stripe below the eye. Occasionally the birds may have a white chin, spots on underwing coverts or bars on undertail coverts. Cere, eye ring and feet are pale grey (or pale blue-grey); eye is dark brown and beak tip is black. Talons are black. Chick is white down.

The falcon’s body is streamlined with a relatively long tail and slim build. Wings are long and pointed tapering toward wing tip.

About Birds on Trees

You ever see a bird clutching onto a branch high in a tree and wonder, "What happens if it falls asleep? How could it hold on?"

The avian talon works through a "pulley system of tendons," according to the animal morphology blog Ars Anatomica, and it can lock into place.

"The bird's foot closes and grasps automatically as the ankle and knee joints are bent," we read. "This grasp cannot be released until the limb is straightened again."

So, instead of expending precious energy holding the muscles tight—as you would if you were hanging onto a branch with your fists/arms—the system simply physically locks in place.

A 1990 paper in Zoomorphology goes into more depth about the biomechanics of the lock, which results from the placement of the tendons and evolved specializations of their texture.

And, of course, this wondrous anatomical system doesn't just come in handy on telephone wires, but also during attacks:

Raptors swoop down on prey with talons/legs outstretched. The impact with the prey folds the raptor’s legs against its body, causing the talons to clench automatically, tearing into the prey. The automatic grip is strong enough to kill, and is what allows many hawk species to catch and kill other birds in midair.