Nationally Scarce - a native species recorded from between 16-100 hectads (10km squares) of the OS national grid in Great Britain.
Based on records from the modern recording period, and where:
- There is reasonable confidence that exhaustive recording would not find them in more than 100 hectads.
- Where it is believed to occur as a breeding species within each of these hectads (i.e. discount those that are known to contain only casual immigrants).
The Ordnance Survey national grid has 2,853 hectads that overlap with Great Britain.