Data from: Historical changes in northeastern US bee pollinators related to shared ecological traits

Pollinators such as bees are essential to the functioning of terrestrial
ecosystems. However, despite concerns about a global pollinator crisis,
long-term data on the status of bee species are limited. We present a
long-term study of relative rates of change for an entire regional bee
fauna in the northeastern United States, based on >30,000 museum
records representing 438 species. Over a 140-y period, aggregate native
species richness weakly decreased, but richness declines were significant
only for the genus Bombus. Of 187 native species analyzed individually,
only three declined steeply, all of these in the genus Bombus. However,
there were large shifts in community composition, as indicated by 56% of
species showing significant changes in relative abundance over time.
Traits associated with a declining relative abundance include small
dietary and phenological breadth and large body size. In addition, species
with lower latitudinal range boundaries are increasing in relative
abundance, a finding that may represent a response to climate change. We
show that despite marked increases in human population density and large
changes in anthropogenic land use, aggregate native species richness
declines were modest outside of the genus Bombus. At the same time, we
find that certain ecological traits are associated with declines in
relative abundance. These results should help target conservation efforts
focused on maintaining native bee abundance and diversity and therefore
the important ecosystems services that they provide.