A bird's color usually affords it protection from its natural enemies. These are mainly birds of prey flying overhead. Thus, speaking generally, protective coloration applies only to the upper surface, so that a white throat or under surface does not necessarily render a bird conspicuous to its natural enemies.
Again, a bird may be very conspicuous when seen away from its natural surroundings, but the concealment may be perfect under natural conditions. It has been already mentioned that the gorgeous Blue Mountain Lorikeet was very difficult to discern in its native sugar-gums. A tiger is said to be invisible at a distance of ten yards in a jungle; the black stripes being similar to the shadows of the bamboos, and the light bands to the sunlight between the vegetation.
The White-eye and Tree-Creepers just noticed may be considered protectively colored, for they are difficult to see in a tree. Still, the brown patch on the wing of the Tree-Creeper is conspicuous as it flies. Alfred Russel Wallace, the great evolutionist, supplied a good explanation, when he regarded bright wing bands, white rump, and white-tipped tail, as "warning colors." An enemy is, perchance, perceived by a bird. This individual flies away quietly; others see the bright wing patch disappear, and they seek shelter as quickly and quietly as possible. This is often a great advantage, for, in many cases, all reach safety, possibly, before the enemy has seen one of them. If the first bird had given an alarming call, it would have warned the enemy too.
It is noteworthy that these bright markings on the upper surface are, usually, not visible when the bird is at rest. The white wing patch folds in, the white rump is covered, while, in a white-tipped tail, it is usual for the two centre feathers to be plain throughout (see illustrations of species 313 and 329). The tail is folded, and the white tips are covered by the two non-white centre feathers. The introduced Indian Turtle-Dove, common about nearly every city in Australia, shows the spread-out, white-tipped tail splendidly when flying. The bird itself is barely visible if it settles in the shade or on the soil. The Indian Myna, a city bird, has both white wing-patch and white-tipped tail.
This explanation is also applied to other wild animals; thus many Deer have the white patch on the hind quarters. Other Deer, seeing this warning signal displayed in flight, immediately make for safety. Similarly, Wallace has explained the white tail of a Rabbit.
The Skunk also has this white patch on the hind quarters, but here a different explanation is required, for the Skunk does not trouble to run away when a possible enemy appears. The bright color is here regarded as an "advertizing color." The Skunk has other means of protection, and he is labelled dangerous or objectionable, just as our one poisonous Spider is plainly labelled dangerous by means of a red stripe. An inexperienced enemy may rush at the Skunk, but the means of protection enjoyed by it effectively protects it, and the enemy retires.
It is a rule recognized by collectors that conspicuous animals have generally some effective means of protection, and they are best left alone, or at least taken with caution. This is readily understood when it is considered that a young, inexperienced chicken will rush at a brightly-colored caterpillar. He then retires, endeavoring to get rid of the objectionable taste. For the future, he avoids brightly-colored animals. Thus the bright color is an obvious advantage to its possessor, as it saves a dangerous peck. It is also an advantage to its enemies, for it saves them an unpleasant experience. We are told the Parrot is the only bird with a sense of taste, but it seems that the chicken possesses one also.
Still another phase of color is shown by Diamond-Birds, where three species have a yellow spot, a red spot, or an orange spot respectively on the wing. It is also shown by the Red-breasted Robins. One has a white forehead, one a white cap, and the third a red cap. These colored patches are considered to be recognition marks, so that a bird can recognize its mate, or a bird of its own kind, readily and with certainty.
That rarely-seen, but beautiful, bird, the Mistletoe-Swallow, is fairly common. From several points of view, it is of great interest. Ranging from India, through Malaysia, to Australia, it did not reach Tasmania. Possibly Bass Strait was formed before this bird reached Southern Victoria. Interesting, also, is the fact that no mistletoe is found in Tasmania. This bird is closely associated with the mistletoe, for, wherever you find it, you find the mistletoe. It furnishes another example of those interesting partnerships between animals and plants. It is not related to Swallows, but while it sits on a bough, its external form somewhat resembles that of a Swallow. Its nest is one of the most beautiful of all nests—a finely-felted, domed structure, often suspended in a clump of mistletoe. This bird has a long-continued, pretty, animated song, which is seldom heard, for it is low, and, as the bird is high in the tree-tops, it might be inaudible; but the main reason is probably that our ears are not attuned to pick out these fine songs. It is said that Tyndall found the insects on the Alps almost deafening, while his companions heard nothing. So it is with the high-pitched call of a Bat. Have you heard one? Few have.