Data from: Contrasting effects of land cover on nesting habitat use and reproductive output for bumble bees

Understanding habitat quality is central to understanding the
distributions of species on the landscape, as well as to conserving and
restoring at-risk species. Although it is well-known that many species
require different resources throughout their life cycles, pollinator
conservation efforts focus almost exclusively on forage resources. In this
study, we evaluate nesting habitat for bumble bees by locating nests
directly on the landscape. We compared colony density and colony
reproductive output for Bombus impatiens, the common eastern bumble bee,
across three different land cover types (hay fields, meadows, and
forests). We also assessed nesting habitat associations for all Bombus
nests located during surveys to tease apart species-specific patterns of
habitat use. We found that B. impatiens nested under the ground in two
natural land cover types, forests and meadows, but found no B. impatiens
nests in hay fields. Though B. impatiens nested at similar densities in
both meadows and forests, colonies in forests had much higher reproductive
output. In contrast, B. griseocollis tended to nest on the
surface of the ground and was almost always found in meadows. B. perplexis
was the only species to nest in all three habitat types, including hay
fields. For some bumble bee species in this system, meadows, the habitat
type with abundant forage resources, may be sufficient to maintain them
throughout their life cycles. However, B. impatiens might benefit from
heterogeneous landscapes with forests and meadows. Results for B.
impatiens emphasize the longstanding notion that habitat use is not always
positively correlated with habitat quality (as measured by reproductive
output). Our results also show that habitat selection by bumble bees at
one spatial scale may be influenced by resources at other scales. Finally,
we demonstrate the feasibility of direct nest searches for understanding
bumble bee distribution and ecology.