Since the first article was recieved with interest, I thought I'd quickly try a slightly different tack on a different species. Dusky Thorn was the one hailed in the State of Britain's Larger Moths as showing the greatest decline of all species, so I thought I'd see if my rudimentary stats would show something up. So below we have two graphs. The first is in line with what I'd done for the Heart and Dart & Large Yellow Underwing, in that it is the number of individuals weighted against 'Trap Nights'.
It is now know that this is a species with large peaks and troughs in it's abundance, and it certainly had a few good years as soon as the report was published. It did occur to me that my method would come unstuck if a lot of recording additional effort was put in at times of year when the given species was not on the wing - so more people taking part in the Winter Garden Moth Scheme would cause a drop in the averages of summer species, so I tried this:
And this shows the average catch across the various years - so recording effort is taken into account, but only when the moth is trapped.Interesting that the huge peak of 2009 in the previous chart has been levelled out. Essentially it was well recorded in 2009 compared to total recording effort, but the average catches were, well, average I suppose! 2011 looks like it was a poor year for this common garden species, but I've not yet got all the 2012 data in so can't say whether that is a trend or a blip.