. Animal ecology. Animal ecology. 66 ANIMAL ECOLOGY history which has accumulated up to date in this rather hap- hazard manner. This applies with particular force to facts about the food habits of animals. Until more organised information about the subject is available, it is only possible to give a few instances of some of the more clear-cut niches which happen to have been worked out. 18. One of the biggest niches is that occupied by small sap-suckers, of which one of the biggest groups is that of the plant-lice or aphids. The animals preying upon aphids form a rather distinct niche also. Of
. Animal ecology. Animal ecology. 66 ANIMAL ECOLOGY history which has accumulated up to date in this rather hap- hazard manner. This applies with particular force to facts about the food habits of animals. Until more organised information about the subject is available, it is only possible to give a few instances of some of the more clear-cut niches which happen to have been worked out. 18. One of the biggest niches is that occupied by small sap-suckers, of which one of the biggest groups is that of the plant-lice or aphids. The animals preying upon aphids form a rather distinct niche also. Of these the most important are the coccinellid beetles known as ladybirds, together with the larvae of syrphid flies (cf. Fig. 5) and of lacewings. The niche. Moths ^Caterpillars] llchneumons | jfUJrph^s y- >| LadyblrdB|—-^Spiders | JI ^ -^ ISecretion} Dlsser Wasps iPsammochareaj Fig. 5.—Food-cycle on young pine-trees on Oxshott Common. (From Richards.^^) in the sea and in fresh water which is analogous to that of aphids on land is filled by copepods, which are mainly diatom- eaters. This niche occurs all over the world, and has a number of well-defined carnivore niches associated with it. If we take a group of animals like the herbivorous grass-eating mammals, we find that they can be divided into smaller niches according to the size of the animals. There is the mouse niche, filled by various species in different parts of the world ; the rabbit niche, of larger size, filled by rabbits and hares in the palae- arctic region and in North America, by the agouti and viscacha in South America, by wallabies in Australia, and by animals like the hyrax, the springbuck, and the mouse deer ^^ in Africa. In the same way it can be shown that there is a special niche of carnivorous snakes which prey upon other snakes—a niche which is filled by different species in different countries. In. Please note that these images are extracted from scanned page images that may have been digital
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