The latest report from Michael Walter:
A few tatty individuals are all that remain to remind us of another good heath fritillary season. As hinted last month, it hasn’t turned out to be such a wonderful count as last year as, although there was one exceptional colony which peaked at 840, most colonies actually fared less well. The most remarkable loss, alluded to in my last report, was at a site quite close to the car park, which was the largest colony in 2021 (see graph). This year’s collapse was almost total, as shown with stark clarity on the graph. Phrases such as “How the mighty are fallen” spring to mind!
Butterfly Conservation’s citizen science project, the Big Butterfly Count, begins its three-week run today (15th July). Sadly, it seems inevitable that most participants will, like me, find remarkably few to count, and for many I fear the fingers of one hand will suffice. Numbers aren’t that low in the wood, but at this time of year I can often see five, six or seven hundred butterflies on my weekly walk; today, however, my score was just 166, the third lowest count in 41 seasons. It may be scant consolation, but last year’s total in mid-July was even lower at 137, so whatever factors were suppressing breeding success a year ago still seem to be active today – or perhaps there is a completely new set of problems adversely affecting their life cycles. Interestingly, the heath fritillary, which has a fairly early flight period, enjoyed quite a good season, so the temptation is to say that the differing fortunes of these species must be related to weather at the time of emergence of the adults. However, that is to ignore the bulk of the butterflies’ life cycle: for most species, fifty or so weeks of the year are passed as egg, caterpillar and pupa. So, while it is the adult that attracts our attention, the other three stages are equally important; break the chain at any point in the year, and the cycle collapses.
Even more depressing is the dearth of swallows, house martins and cuckoos, amongst others, for whereas there is a distinct possibility that butterfly numbers will bounce back in a year or two, it seems far less likely that the same can be hoped for with these rapidly declining birds. Thirty or forty years ago I would regularly hear cuckoos in the wood over a six-week period; house martins nested under the eaves of our house; and swallows passed over Blean Woods in the autumn, sometimes flying low along the rides. Unfortunately, recognition of these declines tends to get swallowed up in an intergenerational phenomenon, now graced with its own moniker – Shifting Baseline Syndrome. Our children and grandchildren growing up in this wildlife-depleted age accept it as the norm, but then lament the losses they become aware of during their adult lives; in turn, this further impoverished state of nature is largely accepted as the norm by their children and grandchildren, and so remarkably little concern is evinced as hundreds of species spiral down into oblivion.
Michael Walter