318Re: [beemonitoring] The Soap Collecting Jar
- 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@...
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USGS Patuxent Wildlife Research Center
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T'ai Roulston <thr8z@...>
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06/04/2008 09:35 PMPlease respond to
email@example.comSubject 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.
Associate Director Blandy Experimental Farm
Research Assoc. Prof. Environmental Sciences
University of Virginia
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Boyce, VA 22620
540 837-1758 ext 276
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