Sprotbrough Flash YWT

Site Details: 

Recorders:   Chloe Maillinson          Distance:  1625m           Walk Time:  50mins 

Sprotbrough Flash is one of the richest wildlife sites in South Yorkshire. A mosaic of open water, wetland, woodland and limestone grassland. On the north bank of the River Don it is named after its main feature, a long, water-filled depression parallel to the river. It overlaps with Sprotbrough Gorge, a Site of Special Scientific Interest. YWT is 28 hectares.

magnesian limestone has been mined since the mid-19th century. Mining has since stopped and wildlife has returned to this area. The original quarry can still be seen opposite the River Don, adjacent to the Sprotbrough Flash lake.The long lake from which the name of the reserve is derived is the result of subsidence caused by the collapse of old coal mines.

Wildlife includes common kingfishers, brown hare, grass snakes, Eurasian bitterns, ruddy darters, and the great crested grebe. Plant life includes common twayblade, common spotted orchid, spindle, small leaved lime, woodruff, greater stitchwort, sanicle, and the early purple orchid.

Sections:

S1 From the car park the route goes SW along the edge of the wood next to the hay field   As the sunniest part of the transect  it has has the highest counts and sees Brimstone, Orange Tip, Ringlet, Green-viened White  and Comma. 

S2 enters the woodland road and Speckled wood are seen.

S3  leaves teh road and continues W  into more woodland and more Comma and Brimstone are seen along with speckled wood.

S4 returns back to the road  E and more speckled woods.

S5 is dark with  little to see.

S6 opens into open grassland and favours Ringlet, Gatekeeper, Common Blue and the Skippers with the second highest counts.

S7 is rough grassalnd at the base of the slope  and favours Ringlet.

S8  Re-enters shade along the edge of woodland and counts are low but Silver-washed Fritillary was spoted

2024 Results:  Insufficient data

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

TRANSECT REPORTS

2023 Results:

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%.

  Sprotbrough Flash had  a good year and above teh average trend in common with many woodland sites. The species trends follow the county trends  with another big drop in Small Tortoiseshells with only 2 seen but bucking the trends there was a increase in peacock. Most of the sites increase in numbers comes from Meadow Brown which had a second very good year along with Speckled Wood , Comma, Red Admiral, Brown Argus and Brimstone; all  matching county trends. 

2022 Results:

2022 sees a big increase in numbers up nearly a quarter with the Big winners Gatekeeper and Comma.. Trends pretty much match those of the county with Brimstone on the up as was Orange Tip. Brown Argus appeared for the fist time in August and is likely the migratory cranesbill form . Common Blue also increased  and Holly Blue had an exceptional year as it did in almost all locations. Small Tortoiseshells were not seen after the  beginning of June and their summer generation completely failed in most locations and down to a quarter of last year. Peacock was similar  and almost lost its summer generation although an odd one was seen here in August after a good start to the year.  Comma had an exceptional summer generation and then good numbers in September overall it trebled from last year.  It was also great to see the Dark -green fritillary appear while it was absent last year. All teh browns had a good year but particularly Marbled White and Gatekeeper but smal heath disaapeared and one of teh few browns to show a marked decline with the drought