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

The stars aligned for a bumper year with a massive increase in numbers of 30% . As the second best site for Brimstone in the county it stil managed to double in numbers this year similar to the county figures. As elsewhere in the Vale of York Small Skipper had a great year after a run of poor ones. Disappointedly only 2 Small Tortoiseshells were seen this year which is  pretty typical for the Vale.  Dingy skipper as elsewhere was down this dry spring.  Silver washed fritillary had another good year but not its best. The hairstreaks were a more common sight coming down out the tree tops to nectar due to rain washing away their honeydew. Gatekeeper numbers were exceptional. 

Overall  7% down on the 5 year average was mostly down to the lost generation of Tortoiseshells and Peacocks and to some extent Ringlet although these big losses were compensated in large part by the boom in Speckled Woods.  The golden Skippers were both down as elsewhere.  Birds-foot trefoil is growing  profusely in the chalk roads along the railway-side road this year after its regualr srape so both Dingy Skippers and Commonm Blue had their best year but does not reflect a trend  rather a highly managed habitat of the forest.  Brimstone was up mostly with good numbers overwintering from the boom the year before. Large White  was down, like elsewhere, and Small White up but these two species do show alot of variation site to site and year to year. Green-viened White was up while on most sites were down  possibly refelecting  this is a wet stronghold of this species. The damp loving Orange Tip was also up.   As everywhere else the Vanessids were down especially Peacock even though all species overwintered well, failed to have a summer generation.  As everywhere else Comma had a good year with a strong hutchinsonii generation,  although they disappeared into hibernation very quickly in the second generation.  Bishop Wood is well known for being teh heartland of the counties Silver-washed Fritillary  population was well down on last year. However, considering at least half their rides had  cleared during extensive thinning operation by Forestry England which greatly reduced the violet population although we can expect this to bounce back strongly next year proving how dynamic forest habitat under management, with  a strong human influence on its proceedings .  As with the Green-viened White Speckled Wood had a bumper second brood revelling in the heat. Gatekeeper as elsewhere also boomed but Meadow Brown was down as was Ringlet .  Argent and Sable was recoded on two weeks with 3 individuals seen which is about normal  but not as good as 2019.

Although total numbers were down against 2020  over the three year average it was up near 10%  which is a surprise considering how bad the spring weather was which then created a significant delay in the  main season.  The spring saw very high emergence from hibernation of Brimstone  although the summer brood  numbers were   a bit down  numbers were still 4 times higher.  Orange Tip was also at good numbers  almost double  previous years.  Amongst the white Large  and Green-veined White were average , but Small White saw a noticeable  rise almost exclusively in the second generation. Small Skipper saw quite a drop as did Large Skipper to a lesser extent. The hairstreaks were  alos somewhat down but this might well be due to other factors.  

Red Admiral was down again and Small Tortoiseshell boom continues with a strong 2nd and third brood. peacock emerged from hibernation well and then suffered a disaster with a peak of less than 20% of 2020 good year. Comma also had a bit of a disaster with numbers halved.  They were compensated for in numbers by Silver- washed Fritillary who seemed to boom after  all the forestry thinning operations and ride widening these last 18 months. Their number nearly quadrupled. and was the commonest specie sin the forest for 5 weeks on the trot.  Speckled Wood  also benefited a little.   The other Browns also faired well with meadow browns increasing significantly.  You can speculate that the lush grass growth  from ample rainfall this year has benefited quite a number of species and has  compensated for the atrocious spring weather and delayed emergence.  Gatekeeper bucked the trend of elsewhere and was down but boomed on the majority of transects

Argent and Sable moth showed again after a poorer year in 2020 unless it was missed during lockdown  but not quite a good as 2019 An extensive survey was carried out by volunteers and concluded that the main concentration of the population is centred on S5 down to the log pile but also to the east by the side of the dike proved a hotspot and Hammersike either side of the log-pile and the path west from the main car park 

  Bishop Wood saw a remarkable 42% increase in overall numbers of all species! The highlight was a good many White-letter Hairstreaks were seen for the first time.  Silver washed Fritillary had a early start and a late finish although numbers per week were probably 20-30% down.  Purple Hairstreak was seen in good numbers along with more  Dingy Skipper along the railway side (S2) However things were much influenced by a large new area of nectar plants including Primrose, Dog Violet, Birds Foot Trefoil and Agrimony followed by Knapweed, Teasel, Fleabane, Marsh Thistle, Meadowsweet, Marsh Valerian and Angelica along the railway side (S2) which has grown after being cleared in late 2018 ( S2). This abounded with life throughout the season and saw huge numbers of Peacocks (400 peak) in the last 2 weeks of July along with the Whites and other species.  The summer downpours ment the trees were washed clean of their honeydew, the major food source of some of our canopy dwelling species like the Hairstreaks revealed their presence for the first time at low level and occasionally, very unusually, taking nectar. In addition the foresters moved in with  heavy plant and the wider chalk roads were scrapped and reinforced  with fresh chalk, which meant most of the nectar plants on the ride sides were lost. This greatly reduced butterfly numbers of some species while others simply moved to the railway side. This is very much reflected in the sections counts