Phenological shifts and increases in voltinism within a moth community over a century of anthropogenic change.

In temperate ecosystems, warming temperatures can advance spring phenology, extend autumn phenology, disrupt dormancy regulation, result in phenological mismatch across taxa, and even lead to increases in the number of generations per year (i.e., increases in voltinism). Much of what we know about the impacts of global change on species phenology and voltinism comes from recent decades; however, anthropogenic warming began centuries ago. Using light trap datasets from 1889-1892 and 1919-1922, alongside contemporary records, we document long-term changes in phenology and voltinism for 78 moth species, and changes in occurrence for 169 species, in New York, USA. From 1919-1922 to 2019-2024, we found an advance in spring phenology by 0.55 days per decade and an extension of the end of the flight period by 1.18 days per decade. This shift was largely driven by bi- and multivoltine species, which have added generations extending the end of their flight period by 1.58 days per decade compared to an extension of only 0.49 days per decade for univoltine species. We also document the apparent disappearance of 13 species from the region from 1889 to present, whose ranges now tend to be farther north and at higher elevations, possibly due to global change. As this region becomes warmer and wetter with ongoing climate change, more species may extend their active period or add more generations per year, with the potential for rapid adaptation and consequences for ecosystem function as some insect herbivores become more abundant.