Nationally Rare - a native species recorded from between 1-15 hectads (10km squares) of the OS national grid in Great Britain since the modern recording period
Based on records from the modern recording period, and where:
- There is reasonable confidence that exhaustive recording would not find them in more than 15 hectads.
- 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).
- This category includes species that are possibly extinct, such as those in the Critically Endangered (Possibly Extinct) category, but not those where there is confidence that they are regionally extinct (RE).
The Ordnance Survey national grid has 2,853 hectads that overlap with Great Britain.