Ardea
Official journal of the Netherlands Ornithologists' Union

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Berthold P. (1976) The control and significance of animal and vegetable nutrition in omnivorous songbirds. ARDEA 64 (3-4): 140-154
1. In combined laboratory (Berthold 1976a, b, 1977) and field studies (Brensing 1977) the control and significance of animal and vegetable nutrition in a series of omnivorous songbirds were studied. The main results of these studies are reported and discussed in this review. 2. It was shown for the first time in birds that some omnivorous species have regular spontaneous changes in the ingested amounts of animal and. vegetable foodstuffs. These changes might be based on an endogenous periodicity. 3. Omnivorous species feeding on nutrient-poor vegetable foodstuffs such as berries and other pulpy fruits generally prefer animal to vegetable food. Except for frugivorous feeding specialists such as the Waxwing they can not subsist solely on that type of food, apparently because of a resulting protein deficiency. 4. From laboratory and field studies it is concluded that as a rule, animal foodstuffs are a vital necessity for omnivorous songbirds and that vegetable foodstuffs are a supplementary food for economic reasons which are discussed.


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