Food and feeding habits of Triturus vulgaris (L.) and T. cristatus (LAURENTI) (Amphibia) in two bog tarns in central Norway

The diets oftwo sympatric species of newts, Triturus vulgaris(L.) and T. cristatus(LAURENTI), from two localities in central Norway, have been compared. Adult T. vulgaris ate mainly those Cladocera which can be classified as planktonic, and to a lesser degree those which are predominantly benthic. The food of T. cristatus was predominantly benthic invertebrates and Cladocera associated with the bottom. T. vulgaris larvae ate planktonic - and predominantly benthic Cladocera, and to a certain degree also larger benthic invertebrates, while T. cristatus larvae (July-August) had taken almost exclusively Cladocera, 75% of which can be classified as planktonic. Large T. cristatus larvae (in September) had eaten relatively more benthic prey. These data would fit the hypothesis that the modes of feeding of the species are different: Adult T. vulgaris swim about in the water much of the time, while T. cristatus stay on the bottom. Among the young, T. vulgaris larvae are mainly associated with the bottom, while T. cristatus larvae are definitely more nektonic during most of the summer; large T. cristatus larvae, however, when nearing the time for metamorphosis, become benthic.