Geographical and seasonal variation in food habits and prey size of European pine martens

Although the diet of pine martens (Martes martes) has been described in detail from many locations in Europe, the geographical variation in their food habits is unknown. I reviewed the food habits of the pine marten over most of its geographical range, using 43 winter and 23 summer diet studies. Throughout Europe, the most important prey of martens was small mammals, which represented 47% of all prey in winter (range 14-81%), and 42% in summer (range 12-68%). Small mammals were followed in decreasing order of importance by plant (primarily berries) material (16% in winter, 21% in summer), birds (15 and 13%), medium-sized mammals (10 and 4%), and invertebrates (5 and 15%). Plant material and insects were more frequently consumed in southern regions than in northern Europe during winter. Medium-size mammals and large birds were consumed more often at higher latitudes. The proportion of small mammals (mainly rodents) in marten diets increased from the Mediterranean to northern regions, and reached a peak in the temperate deciduous and mixed woodlands; it declined further north in boreal forests. Across all studies, pine martens showed a functional response to fluctuating rodent numbers, but this was much more significant for bank voles (Clethrionomys glareolus) than for other rodent species. During winter, there was a trend towards a wider food niche and larger prey in the north compared to the south. Prey size in marten diets was negatively correlated with marten body size, but positively related to the number of days with snow cover. The diet of pine martens varied significantly with latitude and longitude during winter, suggesting that winter is a period of limited food availability.