Integrated data on the taxon and morpho-specific year-round diet and endozoochorous seed dispersal by the world's largest grouse, the Capercaillie Tetrao urogallus.

Recent developments in molecular methods for fecal analysis to assess the food habits (scatology) of herbivores have been controversial in terms of accurately identifying which specific plant parts were consumed and quantifying the amount of food ingested. To address this critical issue, traditional methods should be used to describe a multi-component plant diet that expresses the contribution of taxon-specific morphologically differentiated plant parts. Here we present quantitative data from our original high-resolution taxon- and morpho-specific dietary study based on cuticle microhistological analyses of food remains from the feces of the Capercaillie Tetrao urogallus. By providing integrative quantitative dietary data based on the functional classification of different plant parts representing 49 types of food items belonging to four major food categories (seed and fruit remains, leaves, moss fragments, and other plant material like stem or inflorescence fragments), intact seeds, arthropods, and mineral particles (grit/gastroliths), our dataset has potential applications in studies of the diet, endozoochorous seed dispersal capabilities, and the reintroduction biology of gallinaceous birds. We highlight that Galliformes consume different fragments of the same plant taxa with varying intensity throughout the year. Therefore, qualitative methods based on the frequency of occurrence of individual plant taxa using fecal DNA do not provide actual quantitative data on the diet composition in terms of ingested specific plant parts. Hence, a parallel microhistological analysis is essential to describe the full spectrum of the diet of herbivores consuming various plant fragments.