Butterfly Conservation Yorkshire

High Brae YWT

Inglebrough

Northern Brown Argus transect

Details

Walkers Terry Whitaker Distance 1632 Walk Time 55mins Altitude 326m

Situated on the east side of Inglebrough in the Ribble Valley just north of Horton in Ribblesdale. In summer, experience a multitude of plants and flowers, with an expanse of yellow rock-rose in June and the rare Alpine bistort, found here in one of its most southerly locations. Brae Pasture includes areas of hay meadow, calcareous grassland, limestone pavement and woodland. The diversity of habitats support a wide range of plants, invertebrates and birds including notable species such as blue moor grass, bird’s-eye primrose, alpine bistort and frog orchid. Sheep and cattle graze from late summer into late autumn after the traditional late summer haycut.

Sections

S1 from the layby goes to the tree line that runs north south on teh edge of the limestone pavement . S2 and nearby S9 -S11 are in a grassy area just below the pavement and this is where most of teh action takes place . Meadow Brown, Ringlet and skippers are restricted to the grassy area of S2 and S11 and is also favoured by the Common Blue. The Northern Brown Argus reside pretty much in S2-S3 and then S9-11. S9 is a favourite with the Small heath . Dark-green Fritillary very much favours S2 and S10 woodland edge

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

High Brae performed close to average for the county with the major losses being with Small heath which had its worst year ever and Common Blue which alos dropped by 50% in most localities but was also absent from so many sites. As elsewhere NBA had a cracking year beating all the trends . DGF numbers held up which seems to have happened on the very dryest sites while in so many they have had an atrocious year. almost completely lost from the Limestone ridge and Wolds. For the second year small tortoiseshell was absent. The whites did somewhat better.

TRANSECT REPORTS

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%.

A poor year at High Brae down nearly a third in overall numbers. Biggest losers Dark-Green Fritillary was down dramatically in the drought. Other drought sensitive species like Ringlet, Green-viened White, Large Skipper and Small Heath were alos well down and all were down across teh county. Northern Brown Argus was just a tad down while on many sites it suffered a good deal more. Big Winners here and countywide were Red Admiral and Meadow Brown both having record years. The site continues to decline at quite a speed which is worrying.

Results 2022

The signs of some recovery continues with a boom in the browns this year with Small Heath accounting for a good percentage of the improvement with the best year since 2014.

Both Golden skippers reappeared with the exceptionally warm weather but drought was a big factor for other species with last years boom in Dark Green Fritallary crashing. Northern brown Argus held up well but still in long term decline while Common was at least quite a bit up. . Smal Tortoiseshell crashed as it did throughout Yorkshire due to poor quality nettle and no second generation was possible.

Results 2021

From 2014 possibly the best butterfly year by a good margin in recent times there has been a slow decline. However there is signs this has slowed . When many species were peaking in 2018/19 here many were falling which we might guess is down to drought on very thin soil. 2020-2021 wet summers seemed to suit Northern brown Argus as it did in 2016-17 which were universally poor fo rmost butterflies eleswhere and Common Blue and Dar- green Fritillary and Small heath dropped dramatically.

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