Intra‐ and inter‐specific variability in the temporal trends of butterfly phenology in the Northern Alps

Abstract

Abstract Large‐scale declines in insect abundances and richness due to climate and land‐use change have been well documented during the past years. These changes are accompanied by shifts in insect phenology towards earlier appearance in spring and prolonged activity periods in late summer and autumn. The magnitude of these responses to climate change might be masked by intra‐ and inter‐specific variability in phenology and trait expression. Here, we used a large data set of museum records of butterflies from the northern Austrian Alps (380 m to >3000 m asl) and ask to which degree does intra‐ and inter‐specific variability in spring and autumn activity and in the numbers of generations affect the temporal trends in phenology during the last 30 years? For the 17 most abundant species, we found phenological variability to strongly differ among species, local habitats and study years. Ubiquitous mobile species were significantly more variable than habitat specialist and sedentary species. Intra‐specific variability was highest in ubiquitous habitat generalist species and increased during the study period. As consequence, seasonal appearance and composition of local butterfly communities are now less predictable than decades ago. It remains unclear whether this trend causes a rewiring of pollinator food webs.