Bolton Percy
Station YWT
Tadcaster
Site Details:
Recorders: Sarah Mawby + Simon Watson Distance: 480m Walk Time approx 40mins
This tiny site is consists of the old station platform and surrounding track bed of ballast and chalk are are favourites with Common Blue and other grassland species species including Small Heath. The platform has overgrown with shrub along with surrounding overgrown Hedgerows and the open mosaic of yard area has been badly damaged by railway operations . Wall Brown used to be common and Dingy Skipper was seen but not in recent years.
Sections:
The Vanessids very much favour the sunny hedgerow with tall herbs of S1 bordering the field while Speckled Woods prefer the shady trackside woodland of S4+5. S4 is also a favourite for Gatekeepers, Holy Blue Meadow Browns and Orange tips. Common Blue prefers the open area of old track-bed S1. The old platform previously the centre of butterfly action is now overgrown. The site is beginning to scrub up and the beds of Birds foot trefoil are much reduced.
Results 2024
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
Bolton Percy did noticeably better than the county average. Brimstone and Large whites did well and speckled wood did better than many other locations and contributed most to teh better than expectyed result this year. Pity no Common Blue or more worrying Small heath were seen but both had bad years
Results 2023
County wide 2023 results reflect the 2022 and 2023 spring drought with Small Tortoiseshell and Peacock nearly halved for the second year against their 5 year average. Red Admiral arrived in force in July and took advantage of soft nettle growth of the rains and had their best year ever. Drought sensitive species on thin soils were badly hit, particularly Dark -green Fritillary and Northern Brown Argus but also Ringlet, Green-viened White and Small Heath. Less drought affected species along with the hottest June on record built even more on gains last year leading to Comma, Brimstone, Holly Blue and most Browns having a fantastic year reaching all time highs. A increase of 9% overall was mostly due to sheer numbers of Meadow Browns and Gatekeepers ment 2023 nearly pipped 2014 as best year in modern times. Most noticeable was the large differeces between mositure retaining mineral soils of the valleys and thin, dry limestone or sandy soils. A large number of damp grassland, hedgerow and woodland dominated sites benefitted hugely with 3 sites seeing more than 50% increase . A smaller number of thin, chalky, sandy or craggy sites did badly some down up to 25%.
Bolton Percy showed similar trends to teh county but with some exceptionally good results for Holy Blue and Comma and bucking the trend Smal lheath on the lowland location had a good year, Losers were as teh county trends. Overall numbers were above the county trend at 16% due to very good numbers of Small White.
Results 2022
The site had a very much better year and shows many similarities with other sites. Large White was down while Small white was well up compared to last year. Green viened white bucked the county trend and was a tad down here. Orange Tip as elsewhere was up. Its great to see the Common Blue come back and Holy Blue boomed universally. As with elsewhere Red Admiral was up and the Small Torst and Peacock had a disasterous second brood and were universally down as here. In common with elsewhere, and in contrast to the other vanessids, Comma boomed. Speckled wood was up as in the majority of the county. Following the county pattern the Browns did well apart from Small Heath that dropped back on its bumper year last year.
Results 2021
Overall numbers were down rather more than the average for Yorkshire but similar to nearby transects . It did buck the trend with one of the few places where Comma and Holy Blue, Speckled Wood and Ringlet increased which might be related to the increasing scrub. In line with the Yorkshire trends gatekeeper had a good year universally
Results: 2020
Although overall number stayed about the same there were more losers than winners. Losers were in particular Common Blue and Holy Blue but also Peacock ,Small Heath and Speckled woods were down. In contrast Gatekeepers were way up and the boom in Small Tortoiseshells was seen here as well along with gains in the Whites