Habitat Choice and Phenotype‐Limited Feeding Efficiency in Bluegill: Individual Differences and Trophic Polymorphism

Abstract

Individual variation in the foraging behavior of bluegill sunfish (Lepomis macrochirus) was studied in laboratory aquaria containing vegetated and open water habitats. In general fish chose to search for prey in the habitat that provided the highest foraging return, but individuals differed markedly in the degree of habitat selection. Vegetation and open water habitats require different searching techniques for efficient prey detection and individual bluegill differed in their levels of behavioral adjustment to each habitat. Fish using slower searching tactics had the highest foraging rates in the vegetation, whereas individuals searching rapidly fed more effectively in the open water. These behavioral differences in searching rates were found to be correlated with the size of the pectoral fins. Bluegill with longer pectoral fins consistently searched more slowly and spent more time in the vegetation habitat compared to bluegill with shorter pectoral fins. These results indicate that behavioral and morphological variation among individuals can influence habitat—specific feeding efficiency and habitat selection, and may also have direct consequences for models of density— and frequency—dependent habitat selection.