Diet choices made by free-ranging moose in northern Sweden in relation to plant distribution, chemistry, and morphology

Understanding how large herbivores select their diet requires accurate meas urements of the nutritional costs and benefits of food items and the compos ition of plants in the diet relative to the composition of plants in the ha bitat. We followed moose (Alces alces) tracks in the snow and measured bite s of browse plants taken and the number and mass of twigs of the 10 browse species available within the moose's reach and measured morphological and c hemical characteristics of browse plants. The diets of 41 moose in northern coastal Sweden contained 75% Scots pine (Pinus sylvestris) and willow (Sal ix spp.). with the remaining proportion equally divided among five deciduou s browse species and common juniper (Juniperus communis). The moose used ap proximate to 20% of the bites available along the foraging patch, usually t aking only one or two bites on each plant selected for browsing. Moose sele cted rowan (Sorbus aucaparia), willow species, and aspen (Populus tremula) in winter, used gray alder (Alnus incana), silver birch (Betula pendula), a nd Scots pine in proportion to their availability, and avoided pubescent bi rch (Betula pubescens) and Norway spruce (Picea abies). Selection was corre lated with plant morphology but not with digestibility or nitrogen, fibre, or phenolic content. Moose selected browse species offering fewer, larger s tems over those with many, smaller stems. Moose made slight adjustments in their food selection and foraging intensity as abundance of browse plants d eclined, thereby presumably maintaining higher harvesting rates.