The bite diameter selection by moose in relation to twig quality on four phenotypes of Scots pine was studied on the basis of a field cafeteria experiment. Comparison of twig quality was made among: 1) phenotypes, 2) different twig diameters, and 3) mean moose bite diameters. Chemical and morphological analyses of the trees indicated that twig fibre and tree/shoot size strongly affected moose bite diameter choice. Sight and chewing sensation are suggested to be the main browsing strategies used by moose. Moose adjusted the bite diameter among phenotypes on the criterion of similar food quality. The factors involved may play a multiple role in affecting moose foraging. Quantitative features of trees had no significant effects on moose bite diameter selection.