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IV. PROPERTIES OF GAME POPULATIONS: MOVEMENTS, TOLERANCES, AND SEX AND FLOCK HABITS
- University of Wisconsin Press
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CHAPTER IV PROPERTIES OF GAME POPULATIONS: MOVEMENTS, TOLERANCES, AND SEX AND FLOCK HABITS MOVEMENTS Radius oj Mobility. If a crop of game remains on the farm where it was raised, the incentive to produce it is operative for individual farmers. If, on the other hand, the game wanders over several farms, the owners must organize as neighborhood groups in order to make management fully effective. In other words, the mobility of the species determines the minimum unit of management . How far a game refuge will feed breeding stock to a surrounding hunting ground determines the size and frequency of refuges needed. The answer again depends on the mobility of the species. These are simply two examples which show why the property of mobility, or length of cruising radius, is of fundamental importance in selecting a scheme of management. Mobility varies greatly as between species. The yearly mobility may be almost zero in quail, but almost half the circumference of the earth in certain migratory birds like the golden plover or the arctic tern. The recently developed technique of bird banding has shown a considerable variation in mobility as between individuals, and between the sex and age classes of a species, but it remains true that each species has a characteristic range of variation which differs from that of others, and which may accordingly be considered to be a property of that species. The various groups of species display some internal similarity in this property. Thus all the ducks are mobile, while none of the hares and rabbits appear to be so. Some groups, however, display internal variations. Thus ruffed grouse are non-mobile, while red grouse are mobile, and pinnated grouse are semi-migratory. Whitetail deer are non-mobile, while mule deer perform considerable migrations. Almost all of the banding work to date has been done on min 74 GAME MANAGEMENT gratory birds. Non-migratory birds and mammals are as yet almost untouched. Accordingly it is impossible in the case of many species to give detailed figures, or even to compare one species with another. In any comparison of mobility as between species, the unit of time must be taken into account. The daily radius, the radius as between seasons, the annual radius, and the lifetime radius may each be an entirely different thing. Within a given species the environment must also be taken into account. Elton (1930) thinks that a sense of disharmony with environment tends to stimulate movement. Overpopulation, weather, activity in the decimating factors, or deficiency in the welfare factors probably stimulate it. These are all temporary disturbances of the environment. Possibly certain adverse environments are so constantly disturbed that mobility is permanently stimulated. In quail, for instance, there is reason to suspect that annual mobility increases toward the edges of the geographic range. 1t has already been noted that quail, and possibly other species, tend to become cyclic toward the edges of the geographic range. Fluctuation in population and free movement of populations seem to go together in the gallinaceous birds (but not in waterfowl or mammals). Likewise the opposite properties of saturation points and low mobility tend to be associated. There is possibly some connection between the property of population limits and that of mobility, although its nature is yet to be explored. The only adequate study as yet made of the mobility of any non-migratory game bird or mammal is the Georgia Quail Investigation . Stoddard (1931, p. 175) banded 1410 bobwhites in spring during two successive years on two plantations. Within three years he had recaptured 200 of them, either by retrapping or by finding them in the bags of shooters. Table 4 gives the frequency of the various distances between the point of banding and the point of recapture. The frequency of the time intervals between banding and recapture was: after first breeding season but before the second, 77 per cent; after the second but before the third, 17 per cent; after the third but before the fourth, 6 per cent. [3.227.239.160] Project MUSE (2024-03-28 16:10 GMT) PROPERTIES OF GAME POPULATIONS 75 The substantial parallelism in results between the two different locations studied makes it safe to conclude that on the Georgia preserves nearly half the quail spend their life-span within a quarter-mile of their birthplace, while few ever wander more than a mile. Individuals, rather than coveys, are the unit of movement . One covey moved as much as a mile intact, but the...