Wenthillside
Private butterfly reserve
Owned by Les Driffield
Details
Walkers: Les Driffield & Tony Wilson Distance: 1920m Walk time : 1 hour Altitude : 39m
Wenthillside is a privately owned and managed eleven acre conservation site in West Yorkshire.bought in 2013 and the lower field in 2017, mostly down to rough un-farmed grass with several small areas of trees and scrub, the lower 3.3 acre field bare agricultural destined to be a wildflower meadow. A SW facing magnesium limestone hillside with a large and varied wildlife content. To date 23 different species of butterfly, 19 regularly, including a large colony of Marbled White
Sections
S1 is an old agricultural field and somewhat improved and has been reseeded and replanted grassalnd. It has the highest counts with Meadow Browns and Gatekeeper at their most numerous here . It also a favourite with Brown Argus , Common Blue, DG Fritillary , Small Copper and the Vanessids and the Whites
S2 with its hedge line and Speckled Woods appear.
S3 comes onto the calcareous grassalnds plus woodland mosaic is the most shaded area and Speckled Woods are at the highest score
S4 grassland are the home of the Marbled Whites and Large Skippers plus Ringlets but also Silver washed Fritillary are seen close to the wood to the west
S5 boundary is an agricultural field at teh top of the hill is similar to S4 but numbers a little lower
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
Wenthillside did rather better than the county average. This is typical of dry hillsides elsewhere which have seen a recovery after two years of drought. Ringlet managed to nearly double over last year while meadow brown was down 80% has been seen elsewhereas these two species go in opposite directions with wet and dry. The disaster was only one Silver washed Fritillary was seen and zero Dark green's
Results 2023
County wide 2023 results reflect the 2022 Heat and 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 moisiture 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%.
Wenthillside had a very good year with new species and a big increase in overall numbers much greater than the county average. The species trends follow fairly closely the county with large increases in brown family particularly Gatekeeper, Marbled White and Meadow Brown. In contrast to the drought sensitive Ringlet dropped back . Small Heath also appeared for the first time along with Wall which almost everywhere else saw a decline so this is promising. Speckled Wood also saw a rise along with the vanessids bouncing back after a poor year last year. Dark-green Fritillary had a very poor year everywhere and this is reflected here. The whites were also abundant with a big increase of Small White liely as a consequence of migration.