This year started reasonably, with good Spring and early Summer records. However, from late May, there was very little rain, and it was already very warm. Silver-studded Blue emerged from Week 10 (10th June) but extreme heat from late June onwards meant that numbers were never high, and, as this weather continued, peak season for many species was quickly over. Gatekeeper emerged at the end of June, and the season was over by mid-August, with Gatekeeper seen unusually in shade, rather than exposed on scrubs and brambles in direct sun. There was no recovery during a very poor September. A total of 24 different species were seen, the same number as last year. The annual index across all species was 1,501, the sixth highest of the eight monitoring years, and the lowest since 2017.
Gatekeeper numbers just about managed to improve on last year's poor show, but Silver-Studded Blue numbers were down by more than half, to a total (297) which was the worst since 2017. Meadow Brown was also slightly lower than last year, and absent after early August. Small Heath, by contrast, had a good year, seen each week following an early emergence in May. Large Skipper numbers also recovered after a couple of poor years.
It was a poor year in particular for Small Copper, with only 4 individuals seen (a trend which was noted elsewhere across the New Forest), and Small White were down by over 70% on last year, with only 23 seen. The nine Silver-washed Fritilliary seen represents a welcome increase on last year, despite a shortened season, and the presence of both Painted Lady and Clouded Yellow also shows the impact of southerly winds, bringing migrants. Several occasional species were missing, with no sightings of Ringlet, Brown Argus, Marbled White or Common Blue, although Orange-Tip, Dark Green Fritilliary, and Green Hairstreak did show, with the latter appearing in new parts of the route.
Several common, garden butterflies were particularly scarce this year, such as Comma (only one seen), Small Tortoiseshell (two), and Red Admiral (five).
Overall, 2022 was far from a classic year, with 14 of 24 species declining from the previous year, and overall numbers considerably down on each of the past five years, and barely half the totals seen in 2019 and 2020.
2022 - a year of record heat and drought
Butterfly of the Year, 2022
Seeing 3 Green Hairstreak was good, and finding them in three different parts of the route - one alongside Latchmore Brook in Section 1, one in the drove between Alderhill and Sloden enclosures (Section 3), and the final one inside Alderhill (Section 5), was particularly satisfying.
Climate change and butterflies
Global warming appears to be having a significant impact on our weather, and this is now showing in the decline of butterfly species. It might be expected that the outcome of drier, warmer summers could be an increase in butterflies - as these are insects which need a minimum temperature of around 13 degrees to become active, and cannot fly in the rain. However, this study is showing the opposite - the extremes of heat and drought this year had a hugely detrimental impact on the numbers, and after the worst of the heat was over, there was no late emergence. There is some limited evidence for the increase in species more used to hot, dry conditions (such as Grayling, Painted Lady, Clouded Yellow), but this is out-weighed by declines in formerly common species. As usual, after a particularly poor year, the question remains whether this is just a one-off, and certainly there have always been fluctuations in population size, but it is increasingly obvious that the climate emergency is leading to a dramatic decline in butterflies locally.