Thorpe Marsh YWT


Site Details

Recorders: Michael Townsend Distance 3550 Walk Time= 1-1.5hrs

The land here was owned by the power station that used to stand just to the east, and the land has been managed by Yorkshire Wildlife Trust since before the power station closed. There is an old railway embankment that bisects the site, and the East Coast Mainline runs along the western edge. The Ea Beck is to the south. The island of land between all these areas meant it was never intensively farmed, and ridge and furrow landforms can still be seen in the fields. The land was purchased by the Central Electricity Generating Board in the 1960s for tipping fly ash on a large site to the east and beyond that the cooling towers of the old power station still stand. This has meant that a great mix of plant species have flourished. Its pastures lined with hedgerows, ponds, lakes and small woodlands have varied habitats. management is by Cattle grazing and an occasional mow in August and September. Scrub encroachment is dealt with by hand when in small areas and foot paths kept strimmed. Purple Hairstreask are seen amongst the mature oaks some years.


The very noticeable change is 2019 and 2020 in the rapid increase in particularly . Now section 4+5 is responding similarly.

S1 and S6 woodland is prefered by Speckled Wood pr

S7 is best for Common Blue, Small Copper, Small Skipper, Hedge Brown, Small Skipper and Ringlet and Meadow Brown

S7and S8 is prefered by Comma's and Peacocks

2020 results

Although one of the poorest years for some time being 11% below the 5 year average there are interesting trends.

It is also nice to see Dingy Skipper and Small Heath return even if wanderers

The main factor is the drop in Meadow Brown down nearly 1000 compared to last year but still fractionally above the average. There is a good deal of recovery in numbers of the other browns with Ringlet bouncing back to near normal after the massive loss in 2020. Gatekeeper also came back while on almost all other sites they had a really good year. Your left wondering how the flooding of 2020 is stil working its way out.

Small Tortoiseshell continued to boom as it has on most sites. Orange Tip stays low and although it boomed on most sites but not here. The whites had a poor season particularly Small White as elsewhere.

Transect reports 2020

2020 results

Although numbers have increased significantly in 2020 it is dominated by Meadow Brown while many other species had big losses. Ringlets were well down but does require a damper environment than Meadow Brown and following the heat of 2019 and drought of spring 2020 could easily be responsible. However the Whites and Skippers are also down along with Orange Tip Again in common with many other transects. It is Common Blue that has suffered the most along with Brown Argus, Small Copper.Dingy Skipper was not recorded this year. In line with many other transects Small tortoiseshell saw an increase.

Michael Townsend summarises the year:

If one discounts the high numbers of Meadow Browns, 2020 was overall one of the worst three of the nineteen transect years. Only 2007 and 2008 were as bad. 2007 was the year of severe local flooding that also poured on to the nature reserve, affecting butterflies and forcing the missing of three weeks counts including the normal peak for Meadow Browns and Ringlets. The effects of the flooding probably led to reduced numbers in 2008.

2020, therefore, was an unusually poor year for most species.

Meadow Browns had easily their second-best year, only 2013 being better. The only other species with better than average years were Brimstone (fourth-best but still with low numbers), Small White (also fourth-best) and Peacock (equal fourth best).

Average years were had by Red Admirals, Orange Tips (but well down on 2018 and 2019) and Small Tortoiseshells.

Worse than average years were had by Small Skippers (worst since 2011), Large Skippers (worst since 2013), Large White (equal fourth-worst), Green-veined White (sixth-worst), Small Copper (equal fifth-worst), Common Blue (well down on the previous three years), Comma (fourth-worst), Speckled Wood (second-worst, only 2007 was worse), Gatekeeper (second-worst, only 2007 was worse) and Ringlet (third-worst, ahead of only 2007 and 2008).