Data from: Estimating abundance of the federally endangered Mitchell’s satyr butterfly using hierarchical distance sampling

1. Estimates of animal abundance are essential to conservation biology and
are sorely lacking for many endangered species in the United States of
America. This lack of knowledge may disproportionately affect butterflies
in the USA, which form the largest group of federally protected insects
(20 of 62 species). 2. The Mitchell’s satyr butterfly, Neonympha
mitchellii mitchellii, is a federally endangered species found at 18
highly isolated sites in the Eastern USA. Currently, surveys are conducted
by meandering through habitat and recording the number of butterflies
observed. These surveys are efficient in terms of staffing and time, but
the data from these surveys cannot be used to estimate abundance. Mark
release recapture surveys generate estimates of demographic parameters and
have been conducted, albeit infrequently, and require high staffing levels
and weeks of fieldwork to generate estimates with reasonable error. 3. I
employed hierarchical distance sampling along line transects to estimate
N. m. mitchellii abundance at one site in lower Michigan, USA. This method
requires one observer to traverse a series of transects at a walking pace
and record the number of butterflies observed and their perpendicular
distance to the transect line. My results suggest that this method is as
cost efficient as meander surveys but generates reasonable estimates of
butterfly abundance.