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Harvard Forest Symposium Abstract 2009

  • Title: Pitfall trap designs to maximize spider richness and minimize amphibian by-catch
  • Primary Author: Clarisse Hart (Harvard Forest)
  • Additional Authors: Aaron Ellison (Independent)
  • Abstract:

    Pitfall trapping is the most common collection method in arachnological research. The pitfall trap’s ability to provide accurate richness estimates has been scrutinized, but little work has addressed the traps’ significant problem of capturing non-target amphibians and small mammals. Common modifications to the basic spider trap design (e.g., funnels and raised lids) serve directly to protect the trap from rain and debris, while indirectly minimizing by-catch of large and medium-sized animals. But these methods do not prevent capture of smaller amphibians, and furthermore are not systematically employed by all practitioners. I investigated the effects of four pitfall trap modifications on spider richness and small amphibian capture in a mixed hardwood/conifer forest in central Massachusetts. Five randomized replicates of eleven trap designs (raised lids, interior funnels, mesh collars, and solid collars) were set in rows spaced 20 meters apart over two spring weeks—the first week dry (4mm of rain) and the second wet (33mm of rain). Analysis showed that total spider richness at the family level was unaffected (p=0.07) by the trap modifications. Salamander capture (n=29 from 110 traps) was affected by the trap modifications (p=0.004), with unlidded traps across designs more likely (p=0.02) to result in salamander mortality. Between the two collection weeks, there were also differences in spider richness (p=0.003) and salamander capture rates (p=0.005), suggesting that precipitation may be an important factor to consider when analyzing richness data collected from pitfall traps.

  • Research Category: Biodiversity Studies, Conservation and Management