If one wants to watch vultures, a good tactic is to hang out in the vicinity of carrion (sigh).
For most of us, finding carrion before a vulture does is not easy — except possibly during a seasonal die-off, such as what happens with spawning Kokanee. The carcasses of spent fish attract bears and birds for weeks on end.
However, merely spotting vultures does not guarantee that they will be seen in their horaltic pose, and that is what I set out to see. The horaltic pose of vultures (and a very few other large birds) involves perching in the sunlight with spectacularly spread wings. There are questions about this pose, none of which is easy to answer.
• Why do vultures do this? Speculations are that the pose might facilitate: drying the wings, raising the temperature of the bird after a cold night, baking parasites. At one time or another, the purpose probably involves any of the three reasons.
• Why is the pose given the odd designaton, horaltic? The etymology of the name is obscure, although I suspect that it refers to the Egyptian god, Horus, which is sometimes represented by spread wings.
• Why did I want to see it? Well, it is an unusual pose for any bird and a spectacular one at that. It is certainly worth seeing.
I finally learned when and where to look in the trees above a local spawning creek.
A hint as to forthcoming vulture scavenging is the sighting of a kettle of vultures.
The dorsal surface of the Turkey Vulture looks black from a distance, but is actually a deep brown. Along with that, the adult vulture’s head is red and its hooked bill is ivory.
The underside of the vulture’s flight feathers are light, making the ventral surface two toned.
A Turkey Vulture strikes a horaltic pose as it rests on the branch of a red cedar. It is early morning, and this pose seems to be struck to warm the bird with the first rays of sunlight following a cool night.
Sometimes the brownish dorsal surface of the wings is exposed, sometimes the two-toned ventral surface is exposed.
Here a juvenile vulture (grey head) warms its dorsal surface, while an adult (red head) exposes its ventral surface in a somewhat different stance. The adult’s pose is reminiscent of that of a heron, which sometimes uses this stance to raise wing temperature so as to allow sunlight to kill its parasites. Indeed, the adult vulture on the right was seen to be picking things out of its feathers.
An adult Turkey Vulture faces the sun and adopts a pose apparently used to cook its parasites.
Perplexing sky
Down here on the surface of the earth, we are used to judging distance with the help of contrast: distant objects have a lower contrast than those in the foreground. This insight works for solid objects with sharp boundaries. So, with each successively distant ridge, the trees lose contrast as dark objects become lighter and bright objects become darker.
This is so much a part of our experience that we don’t give it any thought while using it to judge relative distance. It is illustrated with a picture taken through the smoky air of last summer’s fire season (right), but the behaviour is the same, only more gradual, in clear air.
The guideline that contrast decreases with distance can be problematic when dealing with clouds, which range from the opaque to the diaphanous. Consider this morning’s sunrise shot. (The yellowish cast results from the smoke of forest fires farther east, and while the colour adds to the drama, it is not the point of this discussion.)
Rather, look at the contrail on the right side of the picture. We percieve it as being in front of the higher cloud because of its higher contrast. Alas, our perception is wrong.
Consider the geometry of the scene. The sun is above the horizon and so must be shining down on all clouds. However, the contrail is casting a shadow on that supposed higher cloud. Ergo, despite perceptions, the contrail must be above (more distant than) the high cloud.
A contrail (right-hand side) looks as if it is lower than the high cloud, but it is actually higher.
