Wednesday, 27 September 2017

Scottish square-bashing: an update

When I went to Scotland in June, I made a serious effort to record craneflies and fungus gnats in addition to hoverflies. Wherever there was suitable habitat for these families, and it coincided with a potential recording site for hovers, I swept around for a little while. On most occasions my efforts were quite limited, but occasionally I spent a reasonable time sweeping because the weather was not conducive to recording hoverflies.

I've just had a summary of the fungus gnat results back from Peter Chandler. It transpires that I managed 221 species/site records from 30 sites comprising a total of 94 species (about 17% of the British fauna). Unfortunately, my timing was not ideal and I was probably a little early in the year but I did get a few whose distribution is mainly Scottish. The best site list I generated was at Craigellachie where I managed to find 42 species which is almost a respectable total!

Possibly the best record I generated was Ditomyia fasciata from a site near Barnard Castle in Co. Durham (see map of records up to 2011). Apparently I also took a specimen of this species in Wingate Plantation during my visit to John Bridges in June. These two records are clear northward extensions of its known range. Maybe it is responding to climate change but, then again, coverage is not fantastic in NE England (although we did have a summer field meeting based in Durham in 2005).

Figure 1. Distribution of the fungus gnat Ditomyia fasciata to 2011
Peter tells me that fungus gnat recording has been very limited this year – our spring field meeting generated a few records and the Summer field meeting generated about as many records as I generated in Scotland, but with about 30% fewer species (one set of specimens still to be processed may change things).

This feedback is very useful because it highlights just how important parataxonomists such as me could be to this recording scheme. Peter lives in southern England and will never manage to cover the country on his own. So a combination of field meetings and individual efforts is needed to improve coverage. So, do you own a net and a microscope (and pooter)? If so, it is not too late to start collecting fungus gnats and supplying them to Peter.

I’m now hard at work sampling Mitcham Common for its gnat fauna. It is darned hard work as there do not seem to be many gnats about. Perhaps it is the season; but, then again, the site supports relatively young woodland and is infested with bramble so it may just be that it is not a good gnat site. Time will tell.

No comments:

Post a Comment