Whilst waiting for a database to update this afternoon I wondered how easy it would be to get a quick assessment of how a common species had faired over the past few years given the GMRG dataset. This first chart simply shows the number of records per year for Heart & Dart and Large Yellow Underwing over the past 22 years.
But of course that doesn't take into account recording effort - there was a lot more trapping done in the mid naughties, so this one takes into account the number of 'trap nights' in each year.
I'm no statistician, but it looks to me as thought the pre 1995 data should be excluded from any further analysis (which makes some sense in terms of GMRG's formation etc), but also that Large Yellow Underwing is being recorded as frequently now as ever.
Perhaps more useful are the next two, which show the number of individual moths, weighted against trapping effort.