Accounting for imperfect detection in species with sessile life cycle stages: a case study of bumble bee nests
For bumble bees and other social organisms, colonies are the functional unit of the population rather than the individual workers. Estimates of bumble bee nest density are thus critical for understanding population distribution and trends of this important pollinator group. Yet, surveys of bumble bee nests and other taxa with sessile life stages rarely account for imperfect detection. Here, we demonstrate the use of mark-recapture methods to estimate the density of bumble bee nests at multiple sites using standardized survey protocols. We detected ~ 30% of nests in a 2-h survey of each 3000 m2 plot. We determined that 4–5 visits were sufficient to estimate the total number of nests at our site with reasonable precision, equating to one-third the effort previously assumed necessary to reliably estimate nest density. Mark-recapture approaches can be used to generate unbiased estimates of density with reduced search effort, while simultaneously increasing the rate at which nests are discovered.
KeywordsBombus Closed population model Mark-recapture Monitoring Nesting habitat Survey design
We thank the Trustees of Reservations and Appleton Farms for providing access to their properties where this study was conducted. We thank Russ Hopping for invaluable assistance in locating study sites. We also thank Annika Greenleaf, Max McCarthy, Moshe Steyn, Erin Wampole, and our sniffer-dogs-in-training, Indy and Molly, for assistance with field work. This work was supported by the US National Science Foundation (DEB1354022) and the US Strategic Environmental Research and Development Program (SERDP, RC-2119).
All authors conceived of research ideas, designed methodology, and collected field data. DI and EC led statistical analysis and writing of the manuscript. All authors contributed critically to the drafts and gave final approval for publication.
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
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