A complete table of the data is available from Leo Shapiro (lshapiro@umd.edu), Sam Droege (sdroege@usgs.gov), or the refuge biologist.
Below is a table of the site numbers and a brief site description followed by a table of results.
Description Number
| ESVA Site 4 (Visitor Center) | 5549 |
| ESVA Site 1 (Maintenance) | 5546 |
| ESVA Site 2 (Housing) | 5547 |
| ESVA Site 3 (Seaside Rd) | 5548 |
Results
| name | 5549 | 5546 | 5547 | 5548 | Grand Total |
| Agapostemon virescens | 32 | 2 | 7 | 14 | 55 |
| Augochlorella aurata | 96 | 5 | 12 | 171 | 284 |
| Ceratina calcarata | 2 | 2 | 11 | 1 | 16 |
| Ceratina dupla | 15 | 6 | 35 | 6 | 62 |
| Halictus ligatis/poeyi | 4 | 8 | 14 | 26 | |
| Lassioglossum bruneri | 1 | 1 | 2 | 1 | 5 |
| Lassioglossum coreopsis | 1 | 1 | 1 | 3 | |
| Lassioglossum near planatum | 1 | 1 | |||
| Lassioglossum oblongum | 1 | 1 | |||
| Lassioglossum pectorale | 2 | 2 | |||
| Lassioglossum tegulare | 3 | 7 | 6 | 16 | |
| Lassioglossum versatum | 6 | 6 | |||
| Lassioglossum versatumsensumitchell | 4 | 1 | 5 | ||
| Grand Total | 164 | 18 | 84 | 216 | 482 |
This set of bowl surveys were placed on the lawns surrounding the visitor center and headquarters complex. Interestingly, despite being on what one would suppose to be less than prime real estate as compared to natural fields, there are huge numbers of bees captured here--on average 8 bees per bowl trap! Despite the large numbers, however, the diversity is low for such a populous catch. These species are associated with disturbed and lawn habitats throughout the region. In our studies of the Memorial Grounds in the center of Washington D.C., for example, we get approximately the same list. Another possible factor may be time of year: in this case the survey was made in early August, while the other samples from the study were from late August and September.
With the exception of the Ceratina species all the species are members of the family Halictidae. These species are all generalists and seem especially adept at colonizing and using the small often weedy flower resources in areas cut regularly. The Lasioglossum versatum and the L. versatumsensumitchell are 2 very similar species that have been shown to differ genetically, but separating the two species visually is a bit tricky. We have a feeling that most of these may be L. versatumsensumitchell rather than L. versatum, but aren't quite sure. Augochlorella aurata is perhaps the most common bee in the region and found in almost all open habitats. The Halictus species are likely to be H. poeyi, but the separation of these species hasn't been resolved.
Interestingly, while each of the sites had about the same species list, the number of bees captured in each field varied quite at bit. Little study has gone into explaining such differences and thus there is plenty of room for further study of even the most basic of factors affecting bee distributions.
Augochlorella aurata - Photo by John Pascarella
