Wallace’s theory was the more widely accepted argument, and later research studies on this topic would be based on the fight for survival aspect that supports the necessity for Alexander camouflage. Other accepted theories to arise in subsequent years included the role that pigmentation plays in retaining heat and continuing the incubation process when the eggs are unattended, as well as signaling unpalatability to would-be egg-eaters and serving as identification for host birds that have parasitic eggs laid in their nests.

Although all these theories have merit, in a recently published review of a series of studies in the Journal of Avian Biology of 14 September, biologists Phillip Cassey and Golo Maurer of the University of Adelaide in Australia take the embryo’s view of its protective covering in offering possible explanations for the purpose of eggshell coloration. One of these explanations validates the original theory put forward by Alexander M’Aldowie where the pigmentation of the eggshell helps to filter, but not block, ultraviolet light for the developing embryo. It is interesting to note that even the darkest eggs, using the emu as an example, allow some light to filter through. It was also noted that pigmentation differs at each end of the egg, most likely to provide directional cues to the embryo, as well as to assist cells and structures in their early alignment.

As in the case of gulls, which commonly lay a clutch of three eggs, with the second egg laid being noticeably and consistently darker than the other two, the variations in eggshell pigmentation could be a significant factor in facilitating staggered hatching. Moreover, it has been proposed that the variations in eggshell coloring could assist the embryo in learning to recognize the difference between light and dark, calibrating circadian rhythms, as well as encouraging DNA repair and shaping bacterial communities within the egg. Researchers have also noted that pigmentation is affected by rainfall and weather, possibly compensating for local and seasonal conditions. Certainly, there is much still to learn about the marvelous world of birds, and with advancing science, more of these mysteries will no doubt be solved.

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American Oystercatchers are migratory birds, with the breeding populations located in the north often migrating to the southeastern areas of the United States during the winter months. Due to development and coastal activities, populations in the Massachusetts area have increased in numbers. In contrast to the northern populations, it seems that the birds that are found along the Atlantic and Gulf coasts, are more established and remain permanent residents of the area. Many IBA’s (Important Bird Areas) have been established to provide the American Oystercatchers with safe nesting grounds, and winter habitats for the migratory populations. There are approximately thirty breeding pairs that are protected by the Hatteras National Seashore IBA, in North Carolina, and the Altamaha River Delta IBA, in Georgia, is home to approximately 250 migratory American Oystercatchers. Many of these IBA’s, including the Big Bend Ecosystem IBA, Cedar Keys National Wildlife Refuge and Hillsborough Bay IBA in Florida, play an important role in the conservation of these beautiful birds. These areas are also motivated by the fact that in the 1850′s, American Oystercatchers had become extremely scarce in the mid-Atlantic areas, and only began increasing in population numbers during 20th century.

Not only does human development threaten these coastal birds, but they also fall victim to hurricanes and oil-spills. All these factors make nesting very difficult for the birds. American Oystercatchers nest on the ground, which enables them to blend in with their surroundings as a form of camouflage. Their eggs are gray in color and are speckled, having a pointed shape which prevents the eggs from rolling away. But no matter how many preventative measures the American Oystercatcher has, it remains up to humans to protect these birds, and the land they live on.

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But the Ptarmigan spends its winters farther north than any other bird. Snows soon blanket its home – brown feathers would be too obvious against the white landscape. So the Ptarmigan molts into brilliant white feathers in winter. This makes the bird almost invisible in its snowy home. Fluffy white feathers even cover the Ptarmigan’s feet – keeping them warm and turning their feet into wide snowshoes.

The Ptarmigan is also unusual in having three different camouflages: Summer-Brown, Winter-White, and in spring, the Ptarmigan becomes a patchy half-brown, half-white. This springtime coat helps hide the Ptarmigan when the tundra is patchy with melting snow.

Even more incredible: the females molt into summer-brown sooner than the males. By late spring, the females are hiding on their nests, in the brown tundra. But the males are still defending their territory- some flashy white can help the males stand out. The Ptarmigan’s molts are perfectly coordinated with the northern seasons.

There are three species of Ptarmigan: the Willow, Rock, and White-tailed. Each has many subtle subspecies. For instance, the “Red Grouse” of Britain is actually a type of Willow Ptarmigan. Since it lives farther south, in regions with little snow, it does not need to turn white in the winter.

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This all begs the question, “Do birdwatchers really need to dress like they are playing war games in order to watch our feathered friends?” Of course, the answer is “No”. The better question may be to postulate whether birds can see color and if they can try to understand what they are seeing in the first place.

Let’s establish first that birds do indeed see color. Birds have color vision and their vision is pretty darn good. Much better in fact, that the vision of humans. Up until the early 1970′s it was widely thought that birds had trichromatic color vision comparable to that of humans – the ability to break things down into three basic colors. Later in the mid-1970′s it was discovered that birds can see light in the near-ultraviolet (uv) range and that spurred on even more study. Today it is widely accepted that the avian eye, not the human eye, is the superior color vision system. It is now believed that birds see more colors (hues) than we do and the colors also appear more saturated to birds than do ours to us.

It’s accepted that birds probably do see colors similar to the way we see them, although not in exactly the same hue. A green field jacket is probably a richer shade of green through the bird’s eyes than what we are actually seeing. The important issue here, is that bird can see you. And thanks to their heightened sense of hearing, they can hear you jostling around behind that bush.

Standing still with tree limbs sticking out of your hat will not endear you any more or less to the bird. Staying still and being patient will earn you more bonus points that if you look like you’re going to carnival in Brazil.

So in the final analysis, it is not so much what you wear, but how you conduct yourself that will bring you the most bird-watching satisfaction. Want to dress like Rambo? Go for it. But while you’re at it, stay hidden behind that tree so the rest of the birdwatchers can enjoy the scenery as well.

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