Bog-trotting. 6. Cropton Forest

Cropton is a Forestry England plantation in the North Yorkshire Moors, NW of Pickering. It is best known for hosting a family of Beavers since 2019, the result of a reintroduction trial in an enclosure which led to the first Beavers being born in Yorkshire in several hundred years. On first sight, Cropton forest might appear an unsuitable habitat to find Bog Bush-crickets. However, there are records, new and old, from Bog Bush-crickets in three afforested areas in Yorkshire: Cropton, Wykeham and Harwood, the more recently planted forests. Across the UK, Bog Bush-cricket appear to hold on to plantations, and small populations survive along rides and clear-felled areas which preserve the original wet heath vegetation (top shot, a naturally regenerating plot with recovering heath). There are three Bog Bush-cricket records, scattered across the forest in three different years: 2005, 2009 and 2012, so we included this forest in the recces for the project. We were encouraged to see that the records were present in or next to open areas and designed a 6 km route to explore the forest ans survey for any Bog Bush-crickets. As bog bush-crickets are now mostly adult, we used our acoustic monitoring device to find them. 

One of the rides across the forest.

The wood was planted during the last century, mainly in the 1950s and 1960s. Lines and lines of conifers of the same age, growing close together creating a dark high wood. Progressively, and particularly in recent times, the management has become more biodiversity friendly, with removal of sections of dense woodland, thinning and allowing natural regeneration and increasing broad-leaf tree cover and also retaining low intervention plots for biodiversity benefits.

Small boggy pools with Sphagnum moss were dotted along the forest.

Two species of Sphagnum mosses.

Blanket bog and heathland are UKBAP Priority Habitats. During our walk, it became obvious that there there are scattered patches of blanket bog and wooded heath covering clear felled areas or access tracks and rides. Deep peat areas will not be replanted, but are allowed to regenerate naturally. From the management plan:

'This plan will continue the management and development of heathland and wooded heath where this will improve habitat networks across Cropton forest. Maintaining a mixed resource of temporary and permanent open space with heathland flora will provide suitable habitat for Nightjar, Tree pipit, Woodcock and other priority species including Small pearl-bordered fritillary and large heath butterfly and adder.'

Today's was the last of the the recces. In future trips, we will carry out the acoustic surveys. We meet up with Clare and Matt, who are collecting water samples for a Beaver environmental impact project in the enclosure where the Beavers have been reintroduced, and get a lift with them. It is a mild day with a breeze and sunny spells, briefer than we would have liked.

We start the walk and we are accompanied by flurries of Peacock butterflies, looking very fresh. They feed on knapweeds and other flowers and bask on the ground.

Peacocks were plentiful.

The Bog hoverfly, Sericomya silentis. The larvae develops in boggy pools and ditches.

This open area looked like it had good Bog Bush-cricket habitat. We heard several individuals and managed to locate a singing male, our first and only sighting of the day.

Singing male Bog Bush-cricket.

The large tracks of Red Deer.

Bog Bush-crickets called from the heath along this path.

When overcast, conditions appear not suitable for calling bush-crickets, and they were silent. We were surprised to hear Roesel's from a ride with long tussocks of grass by a main ride. Later we spotted a long-winged male.

A calling Roesel's Bush-cricket.

Female Emerald damselfly.

Common Lizard.

We identify possible transects for the acoustic survey and head towards the cafe, where we will meet Clare and Matt for lunch before heading back home.

A House Martin chick looks from a very dishevelled nest at the cafe building.

 More information

Cropton Forest Management Plan. Here.

Bog-trotting. 5. Thorne Moor and Crowle

Although we had already visited the section of this large lowland peatland belonging to Lincolnshire, Crowle Moor, today we visited the SW Yorkshire section, Thorne Moor proper. We start at Crowle, and walk through North Tram to cross the bridge to Thorne. It is a hot, humid day, and we struggle with the biting insects on the way back. Deer flies and ticks bother us.

Cotton Grass by North Tram

The bridge crossing to the South Yorkshire side of the Humberhead Peatlands.

Odonata

It is a good day for dragonflies and damselflies. I'm impressed by the numerous Emerald Damselflies. Migrant Hawker, Black Darter, Black Tailed Skimmers and Southern Hawkers are present, possibly a Common Hawker over a pond. Some illustrative photos of the records follow.

Emerald.

Southern Hawker.

Black-tailed Skimmer.

Black Darter female.

Male Emerald perched on heather.

Bush-crickets

Like at Crowle, they seem to be present along the rides well inside the reserve. The rough grasses on the side of the rides are different from those on the heathland area, possibly affected by the different soil by the surfaced roads.

Male Roesel's Bush-cricket calling. This one was on the heathland.

And this one basking.

Long-winged Coneheads are also plentiful.

And what about Bog Bush-crickets? We are almost in the central part of the reserve, on the path leading to the observation platform when Sarah hears a male calling (top shot). We manage to spot him, close to the ground and very aware of us, changing its position to hide better in the undergrowth and incredibly well camouflaged. I'm pleased that I manage some photos.

Location of calling male. Mainly heather, bracken and birsh saplings with some purple moorgrass.

Another photo of the calling male.

Just a few minutes later, Sarah spots a female. She is easier to photograph.

Bog Bush-cricket female.

And that's our Bog Bush-cricket haul of the day. We have our lunch at the top of the platform and afterwards explore the area immediately around it, which looks promising, without success. We do some pilot acoustic transects and head back before it gets any hotter. 

Female Meadow Grasshopper.

Butterflies

Peacocks, Red Admirals and a Common Blue make the list for the day.

Red Admiral.

We spot some interesting plants along the way, this is a selection.

Marsh Pennywort.

Royal Fern.

Round-leaved Sundew and Sphagnum moss.

Orchid.

Greater Bladderwort.

Bog-trotting. 4. Crowle Moor

For today's recce we stray just across the Yorkshire border into North Lincolnshire, to visit Crowle Moor. This reserve is a section of the largest lowland raised bog in England, the Humberhead Peatlands National Nature Reserve. The NNR is composed of Thorne, Hatfield, Goole and Crowle Moors, what remains of an extensive, raised bog, a thick and growing dome of peat. Manual extraction of peat for domestic use in the XIX century was at low scale and superficial allowed for the quick recovery of the Sphagnum mosses, but  drainage, commercial extraction of peat and land reclamation or 'warping' degraded the peat bog. After decades of local opposition to the destruction of the bog, environmental activism and the documentation of the presence of over 4,000 species of insects in the site, commercial peat extraction stopped in sections until finally stopped completely in 2001. By that time, and despite its degraded status, it was clear that the Humberhead Peatlands held a lot of biodiversity and it was declared a National Nature reserve, SSSI and SCA. Crowle Moor is located on the south eastern side of the area and managed by the Lincolnshire Wildlife trust and North Lincolnshire Council. Currently drainage is carefully managed in 'cells' to keep the water table raised so that the peat bog can recover. It is fiendishly complex work as the drainage network is extensive and the extraction of peat means that surface levels differ across the site.

It was mostly overcast, but warm, again, we were spared most of the biting insects! After meeting our hosts for the day, aka bogtrotter and Ted, local naturalists that know the moor inside out, we start walking along the track towards an area of wet heath where Bog Bush-crickets have been seen.

This piling is a dam holding water in the moor to keep the bog moist, part of the conservation efforts for the site.

Today we have our acoustic receiver, the little red device attached to a phone, which will allow us to record bush-crickets by detecting their almost ultrasonic calls. There were many conehead nymphs and other bush-crickets calling.

A tall wall of Bracken bounded the track before it opened up.

It wasn't long before Ted called he had seen the first Bog Bush-cricket of the day, a female late instar nymph.

Round-leaved Sundew.

Stepping just out of the track was quite treacherous, with very boggy and uneven terrain. Hopefully, the acoustic device will allow us to record bush-crickets across a wide transect following the track itself.
We found several more Bog Bush-crickets near this single track, and Sarah could even hear them calling, what a superpower! We noticed Bog Bush-crickets were with one exception present on Purple Moorgrass, away from Cross-leaved Heath, which was quite different from our previous trips.

Roesel Bush-cricket.

The competition

Soon we found out that Roesel's have also colonised Crowle, and found this calling male (above) not very far from where we spotted the Bog Bush-crickets. Roesel's are undergoing a dramatic range expansion across the UK. Both species might compete where they meet and there is research in southern Sweden showing that Roesel's might outcompete Bog Bush-crickets, with Bog bush-crickets declining in areas where Roesel's were experimentally introduced. We will follow this up with acoustic surveys to assess the extent to which Roesel's are expanding into wet heathland.

After lunch in the car park, including a delicious slice of fruit cake baked by bogtrotter, we moved to the southern side of the reserve. There, after walking all round we found no signs of Bog bush-crickets, but Roesel's were all along the main path along a ditch and also at the entrance of the south end. The habitat was spot on, with even the delightful Bog Rosemary present along with cross-leaved heath and purple moorgrass. It was late afternoon and overcast, so conditions might not have been ideal for them. 

Wall Brown.

A very large long-winged Roesel's female on the entrance to the south area of the reserve.

Black-tailed Skimmer.

Bog Rosemary.

Cross-leaved Heath.

Emerald Damselfly?

An Easter Fox Spider on the track.

More information

Berggren, A., and M. Low. 2004. Exclusion of the native bog bush-cricket Metrioptera brachyptera by the currently invading Roesel’s bush-cricket Metrioptera roeseli." Entomologisk Tidskrift 125 (2004): 125-32.

Rotherham, Ian D. 2010. Yorkshire's Forgotten Fenlands. Wharncliffe Books. 181 pp.