Current notions of“pollinator decline”and“pollination crisis”mainly arosefrom studies on pollinators of economic value in anthropogenic ecosystems of mid-latitudetemperate regions. Comprehensive long-term pollinator data from biologically diverse, undis-turbed communities are needed to evaluate the actual extent of the so-called“global pollina-tion crisis.”This paper analyzes the long-term dynamics of pollinator abundance inundisturbed Mediterranean montane habitats using pollinator visitation data for 65 plant spe-cies collected over two decades. Objectives are (1) to elucidate patterns of long-term changes inpollinator abundance from the perspectives of individual plant species, major pollinatorgroups, and the whole plant community and (2) to propose a novel methodological implemen-tation based on combining a planned missing data design with the analytical strength of mixedeffects models, which allows one to draw community-wide inferences on long-term pollinatortrends in species-rich natural habitats. Probabilistic measurements (“patch visitation probabil-ity”and“flower visitation probability”per time unit) were used to assess pollinator functionalabundance for each plant species on two separate, randomly chosen years. A total of 13,054pollinator censuses accounting for a total watching effort of 2,877,039 flower-min were carriedout on 299 different dates. Supra-annual unstability in pollinator functional abundance wasthe rule, with visitation probability to flowering patches and/or individual flowers exhibitingsignificant heterogeneity between years in the majority of plant species (83%). At the plant-community level, there was a significant linear increase in pollinator functional abundanceover the study period. Probability of pollinator visitation to flowering patches and individualflowers increased due to increasing visitation by small solitary bees and, to a lesser extent,small beetles. Visitation to different plant species exhibited contrasting changes, and insectorders and genera differed widely in sign and magnitude of linear abundance trends, thusexemplifying the complex dynamics of community-wide changes in pollinator functional abun-dance. Results of this investigation indicate that pollinator declines are not universal beyondanthropogenic ecosystems; stress the need for considering broader ecological scenarios andcomprehensive samples of plants and pollinators; and illustrate the crucial importance of com-bining ambitious sampling designs with powerful analytical schemes to draw reliable inferenceson pollinator trends at the plant community level.
