On the Importance of Landscape Heterogeneity in Northern Regions for the Breeding Population Densities of Homeotherms: A General Hypothesis
- 1 January 1979
- Vol. 33 (2) , 182-189
- https://doi.org/10.2307/3543996
Abstract
Most homeotherms in seasonal environments are faced with food shortage in winter or other unfavorable periods. A hypothesis is advanced that such animals make use of disturbances in climax ecosystems to survive and to exploit the more food-productive seasons. Then landscape composition will greatly influence the densities of breeding populations in their normal habitats. Apparently food increases drastically in spring in climax or normal habitats, e.g., from increases in herbage biomass and its nutrient composition, indirectly from regional differences in litter size and from the unsaturated state of northern bird communities. Secondary successions and human cultivation bring new or increased food supply in winter. The landscape effect on breeding populations is related to seasonality, animal movements and distribution, predictability and successional states of disturbances. Landscape effects are traced for a series of Scandinavian homeotherms [Alces alces, Cervus capreolus, Microtus agrestis, Clethrionomys glareolus, Vulpes vulpes, Mus musculus, Apodemus sylvaticus, Rattus norvegicus, Streptopelia decaocta and Larus argentatus], ranging from cervids to migrant birds via some more or less synanthropic species. Recent changes in landscape composition profoundly affected their breeding populations. In the long run certain predictable disturbances may be of no use for animals from other habitats due to competition from settled conspecifics. Some animals may have become adapted to exploit disturbances in climax ecosystems. Such adaptations may be as important as migration or hibernation in other species. Better knowledge of these adaptations or similar general characteristics and of recent changes in landscape composition may enable us to interpret many changes in abundance which are now obscure.This publication has 0 references indexed in Scilit: