One could, I suppose, bite the bullet, and add another sheet with one or two new colors. Joseph Wu has gone in this direction with his elegantly-marked Frigate Bird. And I seem to remember Nicolas Terry doing something similar to get a multicolored frog.
An option for those of us stuck, religiously, with single-sheet color-faithful origami is to confine ourselves to those birds that do follow a 2-color scheme. Pigeons, for instance, which run the gamut of gray-scales and blended patterns, sometimes come in an all-gray or all white body plus reddish feet. Likewise there are quite a few avian species in which the females, who tend to be interested in crypsis rather than showiness, keep their color-numbers to an origami-manageable minimum. (There are, of course, always reasons why an animal has the color numbers it has.)
Another problem is idiosyncratic---or maybe just personally idiotic. A long time ago (20 years… sheesh!) I convinced myself that a standing bird is fundamentally a four-pointed creature, from which it follows that it should be designable from a bird base (5 points: hide one). If you want to use the fancy techniques that have since come on line, to add complexity or detail---open a beak, pry apart toenails, start the wings a-flutterin---this ought to be doable optionally at the last minute, modifying extremities to taste, rather than by designing complexity in from the outset or inventing new bases as I believe Roman Diaz once argued is necessary. All the above poses a certain challenge, since to date I have not been able to pull this off entirely successfully.... Roman in a recent letter even claimed that “The smell of a bird base is difficult to disguise on a model.” But what to do? I happen to like the smell of a bird base.
So here's where we are, on a cold November night.
