House Martin Delichon urbica
No status information available
Contains Ordnance Survey data © Crown copyright and database right 2013
This map shows winter relative abundance at tetrad level 2000/01 – 2006/07. The same five, increasing-sized black symbols represent increasing levels of abundance, derived from analysis of the timed visits. However the class limits and intervals to which the symbols refer varies from species to species. These take priority over the grey symbols used to show maximum counts taken outside the timed visits. The species is unlikely to occur in tetrads with no symbol.
Mean hourly counts from timed visits
Maximum counts from extra visits