Rowcover for assessing nesting density?
I am looking for any tips on sampling nesting density of ground nesting bees in native grasslands. I have read the methods described by Kim et al. 2006* which describe using floating rowcover. The authors covered patches of ground with rowcover at night and captured bees that emerged from nests in the morning. I am considering using similar methods, maybe paired with pan traps beneath the rowcover. Has anyone tried rowcover with or without pan traps to measure nesting density? Perhaps there are other methods I have not stumbled across? Any input is appreciated.
*Reference: Kim, J., N. Williams, C. Kremen. 2006. Effects of Cultivation and Proximity to Natural Habitat on Ground-Nesting Native Bees in California Sunflower Fields. Journal of the Kansas Entomological Society, 79 (4): 309-320.
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I've the same experience. Sampling at Lehigh Gap Nature Center in Slatington, PA, we had 150 Lassioglossum of primarily 3 species in about 4 bowls of a 12 bowl transect, on one date. I planned to resamples in the same area the following year, but it got upset by a major building project for the Center. My explaination was that there were a lot of nests in that area, a rocky/gravely section of hillside. If you want the exact species, I'll dig it out of the data set. What a pain to pin all those tiny bees and separate them by abdominal hair distribution, expecially as I was really new at this. But I did it.
If we knew what we were doing,! it wouldn't be called research.
On 03/28/13, Laura Russo<lar322@...> wrote:
I have a bit of a bee mystery that I thought someone might have insight into.
I sampled for bees in an agroecosystem for two summers, sampling every other week with pan traps at 30 locations (spatially separated) around the fields. The pan traps were yellow and large. There is one day that stands out because, in one pan at one site on June 25, 2010, we captured 54 individual specimens of Andrena commoda. (The identification was confirmed by an expert.)
In two years of sampling, we! only ever caught 5 other individuals of that species.
Does any one have any intuition as to why we would catch so many in just one pan on just one day? What caused them to commit mass suicide in the pan, and where did they all come from? Why June 25th, and why not anywhere else, or in the other year?
Any insights you might have would be greatly appreciated.
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