Transects, or fixed-route walks, are invaluable in the study of population change, but as was illustrated today, the rules have to be followed for the information to be useful.
Last year I walked an hours' transect counting butterflies on the grassland of Tolsford Hill, in late May and late July. This year, the bad weather in spring kept the temperatures down, giving me a (poor) excuse not to get out, and various commitments have deferred the counts until now - mid-August.
Although the weather was similar on 31st July 2009 and 11th August 2010, the numbers and species of butterflies recorded were very different.
Common Blues were by far the biggest increase, with 116 counted, compared with 10 last year - because of the time difference, however, it is not possible to conclude that this represents a real increase (although it has been reported that the second emergence has been strong this year.
... fewer Gatekeepers but more Meadow Browns, and no Painted Ladies or Clouded Yellows this year. It was good to see a similar number of Wall Browns to last year's result, which were very scarce in the cool spring. The grassland (which is partly sheltered from the westerlies) is clearly a favourable habitat, and at this time of the year benefits from clumps of Marjoram and plenty of Small Scabious.
Elsewhere, searches for Grayling at Folkestone again drew a blank, but did reveal three each of second-emergence Dingy Skippers and Small Blues;.... while Kingsdown's rifle range also still holds Small Blues, and a white moth that should be called Brown-veined Moth but probably isn't [no, it's a Sulphur Pearl sitochroa palealis].And at Restharrow Scrape, a Partridge family of thirteen tries to evade the attentions of some crows.