Data from: The influence of habitat accessibility on the dietary and morphological specialisation of an aquatic predator

Individual diet and habitat specialisation are widespread in animal taxa and often related to levels of predation and competition. Mobile consumers such as predatory fish can stabilise lake food webs by ranging over a larger area than their prey, thereby switching between habitats. Although, this switching assumes that the predator has equal preference for the available prey, individual diet specialisation and morphological adaptations to different habitats could potentially prevent individuals from switching between habitats. In this study, we assessed the niche width and individual specialisation in Eurasian perch (Perca fluviatilis) in response to a shift in habitat use by manipulating the ability for this top predator to couple habitats. We ran an 8-week pond experiment, to test the effect of habitat switching on diet and morphological specialisations. We show that habitat coupling influenced individual diet specialisation and niche use in expected directions where specialisation increased with decreasing habitat switching. In contrast to expectations, the morphological variation decreased with increasing diet specialisation. Our results expand on previous work and suggest that individual specialisation and niche width can impact the ability of mobile predators to couple habitats. Furthermore, it shows the importance of individual specialisations in relation to habitat coupling.Diet of perch in experimentStomach content (%) of the perch at the end of the experiment.Stomach_content_Perch_Drottningholm 2013.xlsxMorphology_Drottningholm_2013_TPS_dataTPS file with digitised landmarks for each perch.Morphology_Drottningholm_2013_classifiersClassifiers for the TPS morphology file with details of Pond, Treatment and Habitat