How Archaeopteryx May Have Used Its Wings

From: ornstn@inforamp.net (Ronald Orenstein)

>Someone compared Archai feeding to the methods used by egrets
>and herons and suggested that the forelimbs were used as canopies.
>I can't really imagine an egret or a heron holding out its wings
>while feeding. They just don't do that.

I'm sorry, but they certainly do, or some do. It is an extremely well-known, well-studied behavior. From "The Herons Handbook" by Hancock and Kushlan (1984):

"Use of the wings while feeding is fairly common. In some behaviors wings are used by standing or walking birds. While Wing Flicking, a heron quickly partially extends and then retracts one or both wings. While Open Wing Feeding, a heron extends one wing and leaves it extended for a few seconds before retracting it. While Underwing Feeding, a heron puts its head under an open wing in order to strike at a prey item. While Double Wing Feeding, a heron brings both wings forward and holds them over its head. While Canopy Feeding, a heron brings both wings forward above its head so that the forward edges meet and feather tips dip in the water; this forms an umbrella over the heron's head and neck.

"These wing movement behaviors may function in different ways. Wing Flicking and Open Wing behaviors are probably used to disturb prey, whose consequent movements increase the heron's chance of seeing them. Underwing, Double Wing and Canopy Feeding reduce glare, making prey more visible, and may attract prey to the shade formed by the wings. Canopy Feeding is often assumed by a heron with its back to the sun. Although many herons use these behaviors, some do so characteristically. Open Wing Feeding is typical of the Reddish Egret.... Pied Herons, Tricolored Herons, Snowy Egrets and reef herons also use it. Underwing feeding is also used by Tricolored Herons and by Reddish and Snowy Egrets. Double Wing Feeding is used especially by Reddish Egrets, but, so far as is known, only Black Herons use Canopy Feeding. This latter species walks or runs from place to place, stopping every few steps to form a canopy over its head."

I have seen this myself in the two species best known for using it, the Reddish Egret of the southern US and Caribbean and the Black Heron (or Egret) of Africa, whose Canopy Feeding performance is one of the most startling behaviors to watch of any bird I know.

However, I must confess I am not much attracted by the suggestion that Archaeopteryx fed in this way (though, of course, who knows?). These behaviors in herons are associated with highly derived modifications of the head (including placement of the eyes), beak and neck, permitting the bird to accurately sight on and quickly seize or impale underwater prey from above the surface (not to mention long legs for wading) - and the advantage of such behaviors would seem to be minimal unless they can be followed with a swift, accurate strike. Birds that feed on more sedentary water creatures tend, instead, to find them by touch (e.g. spoonbills, some storks) and do not share the sort of behaviors seen in herons.

Archaeopteryx, on the other hand, seems to lack any such special adaptations (subject to a paleontologist telling me otherwise). Although I don't like to speculate, my own imagined view of Archie is as a generalist feeder, sort of a cross between a chachalaca and a crow or jay. I can certainly imagine it scavenging or foraging along the shoreline, running down small lizards, mammals or insects, perhaps robbing nests of smaller dinosaurs, clambering around in bushes or low trees - but my imagination stops short at its adopting a heron's lifestyle without any of the special adaptations that make such a lifestyle possible.