House Martin Mapper Occupied & Unoccupied Nests, 2017 - 2025, UK & Ireland

This dataset is a record of occupied and unoccupied natural and artificial House Martin (Delichon urbicum) nests across the UK & Ireland.

The data has been collected by volunteers entering their records into the House Martin Mapper App.

The total number of occupied nests is given in the field IndividualCount which is non-zero ‘breeding’ for 1223 records. ReproductiveCondition has been coded as either Confirmed breeding if an occupied nest is recorded and Non-breeding if none of those details are available where the record indicates an abandoned, unoccupied or partially constructed nest. There are 1223 confirmed breeding records and 356 non-breeding records in this dataset.

Dynamic properties include total nest number if provided by the volunteer, nest type either Natural, 1560 records, Artificial nine records or Natural&Artificial 10 records. Property age was recorded as: 1945-1999, Post2000, Pre-1945, or Unsure. Property age was recorded for 413 records: 179 Pre-1945, 160 1945-1999 and 74 Post2000. If the total nests is marked as NA this indicates a partially constructed natural nest.

There is a spatial bias in the records towards areas with more active House Martin nest recording at the time of data collection particularly counties Hampshire and Hertfordshire in England. The records cover a period from 2017 to 2025 however, 1555 records come from 2024 and 2025. Estimated number of broods may not be accurate for all records.