This paper provides a review of data on the effects of the civil war on forest areas in the Democratic Republic of Congo. Only a few of these effects were beneficial, the most important being the collapse of the wood industry. However, the war has increased the number of people that rely on wood for fuel and bushmeat for protein. The presence of soldiers and refugees aggravates this pressure. When people hide they do not necessarily refrain from hunting, because goods, including ivory, can be stocked to be traded when the situation improves. War seems beneficial to the environment only if it keeps people out of large areas. It could be useful to extend the concept of peace parks to war zones. The idea of an international ‘green force’ to protect biodiversity hotspots should be given serious consideration. Awareness is growing that political instability should not preclude conservation efforts from being continued.
(1) The foraging activities of wintering tufted ducks (Aythya fuligula) feeding on freshwater mussels (Dreissena polymorpha) were studied in order to determine whether or not prey-size selection occurred. Eight experiments with captive birds were performed to calculate the profitability of the different sizes of the mussels and to ascertain the most preferred size classes by the ducks under controlled conditions. In two field experiments the influence of prey density and diving depth upon prey-size selection by wild birds was investigated. (2) The experiments in captivity showed that the ducks did not prefer the most profitable prey, but took significantly smaller mussels. Excluding visual clues in size selection resulted in a further decrease of preferred mussel sizes. Being attached to a solid substrate did not affect the relative profitability of the different size classes of mussels. Selection became more obvious the more the size classes offered differed from each other. (3) The field experiments revealed that both increasing prey density and decreasing depth caused an increase in selectivity. Increasing prey density caused a transition towards preference for smaller mussels. The exact effect of decreasing depth on selectivity could not be identified, probably because the prey density used in the experiment was too low. Diving times of the ducks were strongly affected by both prey density and diving depth. (4) Three hypotheses were proposed to explain the selection of sub-optimal mussels by tufted ducks. First, the constraints of diving could change the problem of size selection, as the ducks might do better in swallowing two smaller mussels in one dive instead of one larger mussel. Second, the ducks might prefer smaller mussels to avoid the risk of taking mussels that are too large to be swallowed. Finally, as larger mussels have highly variable profitabilities, it might pay the ducks to select smaller mussels associated with less variance. The data, however, do not allow the hypotheses to be ranked according to their plausibility.
With 1 figure in the text)Analyses of the contents of pellets of Grey herons from different breeding colonies and breeding seasons indicated that the mammal and invertebrate species included in the heron diet varied between colonies and between years. The large differences in mammal species found in neighbouring heronries suggested the existence of important small-scale variability in the exploitation of mammals. Almost no fish and bird remains were found in the pellets. We believe that most invertebrates, even the smallest ones, were actively taken by the herons. Identification of mammal species composition by means of skulls and hair remains gave different results. The shape of a pellet seemed to be dependent upon the (moisture?) conditions during its formation.
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