Fen Grasshopper Acoustic Monitoring: Conservation of a Rare Invertebrate

The fen grasshopper is one of Britain's rarest invertebrates; acoustic monitoring supports conservation management of remaining populations.

Key Facts

The fen grasshopper (Mecostethus parapleurus) is confined to a small number of wet grassland sites in England.
Males produce a distinctive stridulation that can be detected with bat detectors or directional microphones.
Acoustic monitoring allows population density estimation without the disturbance of physical capture methods.
Habitat requirements are very specific: damp, rush-dominated grassland with open, sunny patches.
Drainage and agricultural intensification have caused the loss of over 90% of UK fen grasshopper habitat since 1950.
Conservation grazing at the right intensity and timing maintains the mixed vegetation structure the species requires.

Welfare Considerations

Invertebrate welfare in conservation contexts is a relatively unexplored area, but precautionary considerations support minimising capture and handling of rare invertebrates during monitoring. Acoustic monitoring satisfies this welfare preference while providing effective population data. Habitat management that maintains appropriate vegetation structure benefits fen grasshoppers through the ecological effects of grazing rather than direct intervention.

What You Can Do

Support Natural England and Wildlife Trust reserve management at fen grasshopper sites.
Volunteer for acoustic invertebrate monitoring surveys if you live near suitable fen grassland habitat.
Advocate for agri-environment scheme options that support wet grassland management for specialist invertebrates.
Donate to the Invertebrate Conservation Trust (Buglife) working on rare grassland invertebrate conservation.