. Animal Life and the World of Nature; A magazine of Natural History. THE GAIT AND FLIGHT OF By Frank Finn, , 1. Ostrich's Foot. ALTHOUGH as a general rule birds employ but one pair of limbs at a time in executing the movements necessary for progression, there is a considerable amount of variety in their actions, which are often much misrepresented even by scientific, writers. When moving on the ground, birds have in the ordinary way but two modes of progression—walking, when each foot is advanced alternately, and hopping, when both are moved together in a series of leaps. B
. Animal Life and the World of Nature; A magazine of Natural History. THE GAIT AND FLIGHT OF By Frank Finn, , 1. Ostrich's Foot. ALTHOUGH as a general rule birds employ but one pair of limbs at a time in executing the movements necessary for progression, there is a considerable amount of variety in their actions, which are often much misrepresented even by scientific, writers. When moving on the ground, birds have in the ordinary way but two modes of progression—walking, when each foot is advanced alternately, and hopping, when both are moved together in a series of leaps. By increasing the rapidity of the alternate movements the walk is converted into a run, which is often very rapid. As a general rule, birds are digitigrade—that is to say, they walk on the toes only, the whole surface of at least the three anterior toes being applied to the ground. But there are a few exceptions. The Ostrich carries the digitigrade mode of progression to a greater length than any other bird, the basal joints of its two toes being raised off the ground, so that the foot has a pastern like that of an ordinary ungulate mammal. To this, no doubt, the peculiar springy gait of this great bird is due (see Fig. 1). On the other hand, some birds in which the shank (wrongly called in ornithology the tarsus) is peculiarly short apply this also to the ground in walking, and are thus plantigrade, since the shank of the bird corresponds to the planta or sole of a mammal. This is the case with some of the very short-legged parrots, such as the Salmon-Crested Cockatoo (Gacatua moluccensis), with the typical Swifts {Gyp- selus), and the Mouse-Birds (Collides), all of them being birds which naturally walk very little. It has been stated on high scientific authority that several groups of diving birds, Penguins, Auks, etc., are plantigrade, but this is a mistake; they walk on their toes like other birds, although they may, like many of these, sometimes apply the whole of the s
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