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Biology subjects

Kortmulder, K.

Publications and source records attributed to Kortmulder, K..

2 recordsLinked to original sources

Feeding behaviour, species associations and natural diets of 10 Cyprinid fish species from South-West Sri Lanka.

Sri Lanka has been a favored region for studies of fish assemblages in tropical streams. Food, habitats, reproduction and species segregation have been in focus. The present paper introduces a new approach, comparing feeding behavior of 10 indigenous cyprinid species as observed in aquaria under standardized conditions. It is found that species with similar feeding habits (as to substrate preferences and some characteristics of snapping and processing) are largely separated in their typical habitats in the wild. This conclusion is similar to what others, working with largely the same species in the same region, have found, namely that co-existing species differ in their food preferences. But our conclusion was arrived at independently on the basis of different data. Advantages of behavior studies in this context are discussed, such as identification of evolutionary adaptations in behavior and added information on where in their common habitat co-occurring species collect certain food items that are commonly found in gut content analyses.

ecology↗

An Analysis of the full song of five free-living urban European Blackbirds (Turdus merula); a network approach.

Is the song repertoire of male blackbirds safe-guarded against loss of variability during the breeding season? In order to answer this question the repertoires of five males were analysed from the viewpoint of network theory. In four of the five males a strong coherence of the repertoire was found to exist in anastomoses between strophe types, same elements being reached from different beginnings. The succession of strophe types in song sessions betrayed a mixture of relatively predictable cycles and chaotic connections. The former should facilitate repeated retrieval of a considerable part of the repertoire, while the chaotic component keeps the whole repertoire readily accessible from any point in a singing session. The same mixture may be considered optimal for binding the attention of conspecific listeners. It is concluded that the existing structure of blackbird song repertoires is favourable for the conservation of its richness, but it is as yet uncertain whether this is due to evolutionary (i.c. sexual) adaptation.

animal behavior and cognition↗