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Mid-America Transportation Center

Further Studies to Test Bait Away and Overwintering Biology of American Burying Beetle

Final Report
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Researchers

  • Principal Investigator:
  • Project Status
    Complete
    Abstract
    The American burying beetle (ABB), (Nicrophorus american us) is a member of the carrion beetle family Silphidae, an important group of detritivores that recycle decaying materials into the ecosystem. The American burying beetle is the largest carrion-feeding insect in North America reaching a length of about 4 centimeters and a weight of 3 grams. Although it has historically been recorded from at least 150 counties in 35 states in the eastern and central United States, it declined from the 1920s to the 1960s and is currently only found at the peripheries of its former range. In 1983 the American burying beetle was included as an endangered species in the Invertebrate Red Book published by the International Union for the Conservation of Nature. In the United States, it was placed on the state and federal endangered species lists in August, 1989. Areas within the known range of American burying beetle that will be disturbed through construction activities require conservation measures to meet federal guidelines. Across the range of American burying beetle, the U.S. Fish and Wildlife Service advocates either "bait-away" or "trap-and-relocate" procedures. Unfortunately, surveys and conservation measures for the American burying beetle may create stress and competition among beetles as the bait is placed in an artificial situation where beetles are attracted but cannot feed , or where beetles cannot bury appropriately sized carcasses and must instead continue to defend the carcass (Bedick et al. 1999). Because "bait-away" is designed to attract beetles to an area away from construction, it does not require a Federal permit and is conducted by placing whole carrion onto a structure some distance from the impacted habitat. The carrion is monitored and replaced frequently. However, this protocol impacts beetles including the American burying beetle by attracting them to a bait which cannot be used as a breeding material and by increasing the competition among attracted beetles. In 2006, mortality exceeding 30% was observed in association with field bait-away stations in Nebraska. In 2007, modified procedures resulted in lowered mortality, however attracted beetles moved to and from the bait station spending long periods of time in the environment. In 2009, bait away stations were developed which attracted carrion beetles including the American burying beetle. Video evidence captured feeding and mating behaviors at these stations. However, in addition to attracting beetles, the bait stations also attracted scavengers including the opossum, Didelphis virginiana. Opossums were observed feeding on the carcass and on beetles, suggesting that bait away stations may cause beetle mortality. In addition, baited pitfall traps placed within construction zones receiving bait away stations captured significant numbers of American burying beetles, suggesting that they were not effective as conservation measures. However, baited pitfall traps have a known attractive radius of more than a mile and it is likely that beetles were drawn back into construction zones because of the bait. In 2010, bait stations were modified to exclude opossums, however northern leopard frogs were still able to gain access and resulted in ABB mortality. Light traps were used to assess the success of bait away procedures, however low capture rates of ABB limited the ability to assess results. Preliminary data at light traps on the nocturnal congener N. orbicollis in areas with bait away stations indicated a reduction in these beetles in the area. In addition, survey data in 2009 indicated that mowing and vegetation removal reduced the presence of ABB, an observation that needs to be further tested. This project seeks to develop population estimates in an area before bait away procedures are conducted, to assess the effects of mowing without any other measure being conducted, and to determine activity patterns and overwintering biology of burying beetles to improve conservation measures for ABB in Nebraska and to improve construction timelines and reduce the need for trap and relocate.
    Project Amount
    $ 81,756