Countywide, after a warm winter  April turned  cold, very wet and dull and everything just about stopped and it was near impossible to transect walk all month. By May  there were already  losses  among our spring species being  down a third in numbers.  June brought Arctic winds, a complete reversal of  the Hot June of 2023 when nine  species reached all time highs here and across the UK.  For the  first two weeks of this June  temperatures  were 8’C cooler than  in 2023 around  a frigid  9’C  with  only 5 good days of sun at the end of the month.  The  first three weeks of July had  the same theme of  cool and damp with 5 warm sunny days at the end. Transect walking for many  was very difficult.  The  persistence of the cold and damp over such a long period had a devastating effect with numerically two thirds of our butterflies in the critical later stages of their development; mortality was very high. It was  also one of the longest June  ‘Lulls’  lasting from late May to the beginning of July. When the main flight  season did arrive it  was  slow to build up  and there was no usual peak. Better weather in August helped  save the second generation and very unusually numbers actually went up at the start of September.

  Losers

        For many species it was a triple whammy after  the heat and droughts of the previous 2 years and  last July’s poor flight period this year made it a perfect storm. Overall, annual numbers were down 41% against the average and 45% down on last year.  Half our species were down more than 50% and a quarter down more  than 70%. The Lycaenids, Vannesids and the Fritillaries were amongst the worst affected. Many transect walkers did not see  a single Common Blue, Small Copper, Holly Blue, or Brown Argus until late into their 2nd broods..  Four of our long term declining species Common Blue, Small Heath, Small Skipper and Green-veined White  had  their worst year ever recorded. 

The Winners and less bad losers 

      Northern Brown Argus  had an exceptional year up near 50%  Other species bucking  the trend were Brimstone and Marbled White. The  damp  loving Ringlet on many limestone/dry sites  were up a half  while on most wet sites they fell by a half.  However if it wasn’t for Ringlet holding up the overall numerical losses, this year would have been significantly worse. It often happens when Meadow Brown has a very poor year, like this one, Ringlet does proportionally better, and vice versa in a warm year. 

It has all happened before… many times.    

It was our worst year since 2016 but nearly as bad as 2009  when numbers  were  down 50%.  2024 comes after a run of 6 relatively good years since 2018  along with  rapidly rising temperatures including 2 of our hottest summers which were followed by two of our best butterfly years in 2019 and 2023. It is  likely 2024 was a blip

Grass Wood had a good year rivalling 2019 with a  50% increase in overall numbers following the pattern of the last decade.  The big winners were the browns with Ringlet bucking the county trend and increasing . Speckled Wood had a record breaking year and on thsi site has almost trebled in the last decade that might indicate scrub and tree ingress.   Big losers were Dark-green Fritillary that tanked universally disliking last years drought . Red Admiral here didnt see the big influx seen elsewhere and surprisingly was well down. In contrast  Comma boomed which it did universally .  Northern Brown Argus was down substantially as it was universally  along with all the Whites  Brimstone showed a good increase and had it best showing ever in Yorkshire this year. 

2021 was up  a very large 25% against teh average and well up on last year and and not so far away from the cracking year 2019. Only teh skippers were down which they were in many localities , Interestingly  the whites, the vanessids, northern Borwn Argus and dark green fritillary were all up bucking the trend over most of lowland Yorkshire. Its great to see the threatened species small heath return.  In terms of numbers  most of the increase is down to Ringlet and Speckled wood  both having their best years since 2019. This is one of the very few sites that saw Peacock increase. The reasons are likely the temperatures were much less extreme here than in the lowlands  and may not have experienced the  drought. 2019 remains an outstanding year  and has a big influence on the 5  recorded year average not helped by the absence of results from 2017 and 18 , a period of quite quick changes in habitat by 2019 easily seen by the very large number of Speckled Wood and Ringlet . However we can say 2021 was a little down on 2020 mostly because there has been a dip in these two species  along with the whites.  Northern Brown Argus and Green Hairstreak reappeared in 2020 and is being maintained.  brimstone did very well as it did in most transects . Dark-green Fritillary also maintained good numbers.  From the rarer species point of view it is an improving picture.