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318Re: [beemonitoring] The Soap Collecting Jar

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  • Sam Droege
    Jun 5 5:26 AM


      True, I am generalizing based on experience rather than on data.  Other than some rather small references in papers to differences in observers in netting capture rates I can't think of anything published that looks at comparisons in variability in any set of different techniques.   Maybe some design like this:

      Perhaps use 6 collectors (3 experienced, 3 neophyte) and 18 Study Sites (Vernal bottomlands, transmission lines, or fields, 1 Hectare but perhaps larger so their is a larger collection of bees to sample from)

      Day 1.  Observers are assigned to the 18 sites (3 each) in which they set out bowls in the early a.m. and then net for 1 hour during the middle of the day.
      Day 2. Observers do an additional 3 sites allocated in such as way that all pairs of observers have been matched.  (note that there would be 3 extra sites on day 2)

      It would be nice to repeat this at another 18 sites so that the number of bees wouldn't be exhausted at a site.,.... or perhaps better... simply wait several weeks and do it again on the same sites

      That's my initial idea.  I have a feeling there is a more parsimonious design out there somewhere but can't think of it at this point.   I am also concerned that because we are dealing with day, site, observer, and technique factors here that our degrees of freedom might be eaten up.  This would be a grand summer student project. .... How about doing it at Blandy this summer?  I would be glad to come down to participate.


      Sam Droege  Sam_Droege@...                      
      w 301-497-5840 h 301-390-7759 fax 301-497-5624
      USGS Patuxent Wildlife Research Center
      BARC-EAST, BLDG 308, RM 124 10300 Balt. Ave., Beltsville, MD  20705

      Albert Einstein
      “Not everything that can be counted counts, and not everything that counts can be counted.”

      P Please don't print this e-mail unless really needed.

      T'ai Roulston <thr8z@...>
      Sent by: beemonitoring@yahoogroups.com

      06/04/2008 09:35 PM

      Please respond to

      Re: [beemonitoring] The Soap Collecting Jar

       The advantage of bowls for general surveys is that they are more replicable than following the ramblings, skill, and proclivities of a person with a net.   


      A lot of people are repeating statements similar to this, casually and in submitted manuscripts.  Certainly, any standardized collecting is more repeatable than non-standardized collecting (the rambling, skill, and proclivity part). Is pan-trapping more repeatable than standardized intensive netting? It probably is, but I haven't seen the data yet. There can certainly be big differences among collectors in catching small or speedy insects, but the variability of pan trap catch with placement can be extraordinary as well.  Repeatability is likely to be strongly related to sampling effort (number of collectors/collecting time or number of pan traps) plus variation related to biases in method. None of these factors are well documented or, to my knowledge, easily generalized at this point.


      T'ai Roulston
      Associate Director Blandy Experimental Farm
      Research Assoc. Prof. Environmental Sciences
      University of Virginia
      400 Blandy Farm Lane
      Boyce, VA 22620
      540 837-1758 ext 276

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