#36 Roesel's Bush-cricket by Phillip Whelpdale
Meet Phillip Whelpdale, GIS Manager at the Royal Society of Wildlife Trusts!
Phillip currently works for the Royal Society of Wildlife Trusts as Geographic Information Systems Manager (which essentially means all things maps and mapping!) but for nearly 13 years prior to this he worked for the Yorkshire Wildlife Trust as the Wildlife Data Manager, which gave him the opportunity see a wide range of species and habitats across Yorkshire. He joined the YNU and attended the entomology section meetings, and it was there that the need for a new Orthoptera recorder was flagged and (being unable to say no to anything) he left that meeting as the new Yorkshire Recorder for Orthoptera, which is the group that grasshoppers and crickets belong to, alongside their close relatives – earwigs and cockroaches.
As a relatively small but charismatic group (there are only 27 native species of grasshoppers and crickets in the UK, plus some naturalised species) it seemed like a sensible start to Phillip when compared to some other invertebrate groups with 1,000s of species to get your head around. Grasshoppers and crickets can be found in a wide range of habitats and although sometimes elusive and hard to track down, their sounds are synonymous with warm sunny days of late spring and summer months. It is this sound, called stridulation and created by the males who rub their hind legs or wings against each other, that makes surveying for them much easier as each species makes its own unique sound. Although there are some habitat generalists in this group, they can act as good environmental indicators as they are sensitive to several environmental variables such as habitat size and structure. They are also good for the wider ecosystem both as herbivores and as a food source for other species, particularly birds. Perhaps one of the most interesting things about this group is their potential use as an indicator for climate change. Grasshoppers and crickets are ectothermic, which means that they must rely on external heat to regulate their own body temperatures. Too low or too high a temperature means they are unable to develop or even survive. Each species has its own preferred temperature range and being a generally mobile group of species, they can move to areas that are more suitable as temperatures change. In Yorkshire we are seeing species shift and move as our climate changes and this is particularly apparent in this group, with new species arriving in Yorkshire whilst others march northwards.
Roesel’s Bush-cricket at Spurn NNR.
Consequently, Phillip’s chosen species for this blog is Roesel's Bush-cricket Metrioptera roeselii. They are a medium sized cricket (averaging around 2cm in length) with a characteristic cream colouration on the margin of pronotum (the section of body directly behind the head) and generally have only partly developed wings, though there are exceptions and long winged forms are known to occur. Like other species in this group, its song is characteristic – a long and monotonous mechanical sound. The sound is said to resemble the song of Savi’s Warbler, a rare bird that has been recorded in Yorkshire a handful of times. Historically it was a species that was only associated with coastal vegetation such as saltmarshes and grazing marshes. However, they are quite robust and have been able to survive in often narrow strips of tall rough grassland or neglected field margins along the Humber for decades, where they have been present since the 1950’s.
Interestingly, after decades of staying confined to the banks of the Humber, the species has started to move and spread northwards – with records from as far north as Harrogate. It is interesting to theorise as to why they are only starting to expand now, as sadly climate change isn’t anything new. Perhaps it suggests the range extension has been helped by an increase in the amount of marginal rough grassland vegetation on road verges and in field margins, as a result of the increase in the number of agricultural subsidy schemes in recent years? This in turn could have provided a degree of connectivity through the landscape to enable them to spread. It is also perhaps no coincidence that the reported sightings from northern parts of the region were also of long winged forms. The presence of long winged forms has been shown to be linked to temperature (Gardiner 2009). The increase in the number of record-breaking hot months and summers in recent years has likely resulted in the Humber populations producing more long winged form individuals that in turn have been able to disperse further into other areas of Yorkshire, in search of cooler climes - species adaptation at its finest.
Roesel’s Bush-cricket nymph, found at Spurn NNR.
Recording & monitoring
A dedicated iRecordGrasshopper App exists to help with identification and recording and iRecord is also a useful tool for logging sightings. Help to monitor these species’ changing distributions by submitting your sightings via the app.
Further information and acknowledgements
NEYEDC would like to thank Phillip for his time and expertise in helping to create this blog.