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Studies on the Phyto-Vertical Distribution of Birds

1935; Oxford University Press; Volume: 52; Issue: 4 Linguagem: Inglês

10.2307/4077518

1938-4254

Joseph C. Dunlavy,

Botany and Plant Ecology Studies

BY DISTRIBUTION is meant the natural geographical range of a species or any other taxonomic group of organisms.The concept of distribution carries with it the implication of parallelism to the surface of the earth.There is, however, another well recognized plane of distribution of animals which is vertical to the surface of the earth.The term vertical distribution has become recognized as designating altitudinal distribution over areas of the magnitude of life zones with reference to distance from sea level.Students of bird life have found during comparatively recent years that there is a definite vertical distribution of birds in the vegetation.In order to distinguish this local vertical distribution from the more inclusive zoogeographical term, it is here proposed that the term, p]•yto-vertica[ d;stribution, designate the local vertical distribution of birds in any vegetational formation with reference to distance from the topographical floor, i.e. the ground.It has not been until recently that ecologists have recognized a vertical habitat gradation in the vegetation.Several authors have given some attention to the vegetational levels at which the various types of animals live.The outstanding studies in this field are those of W. C. Alice (Distribution of Animals in a Tropical Rain Forest with Relation to Environmental Factors, Ecology, 1926) and A. A. Allen (Book of Bird Life, 1930).Dr. Alice gives the following zones as a classification of the levels to be found in the tropical jungle of the rain-forest type."1.The air above the forest.2. Tree tops above the main forest roof, 125 or more feet high.3. Upper forest canopy, 75-100 feet high.4. Lower tree tops (second story or mid-forest) 40-60 feet high. 5. Small trees, 20-30 feet high.6.Higher shrubs, 10 feet high.7. Forest floor.8. Subterranean."Dr. Allee does not discuss all the strata given in his classification, nor does he give any criteria for placing the animals into their corresponding zones.Furthermore, he does not take up the mammals or birds.Dr. Allee's classification is a purely botanical one.Dr. A. A. Allen gives a general classification of bird habitats in wooded areas as follows.