The main British Trust for Ornithology (BTO) dataset on the NBN Atlas: Birds (BTO + partners) only has records up to the end of 2015 and is becoming increasingly outdated. This is a very large dataset of almost 152 million records from a range of surveys including Garden BirdWatch, BirdTrack, Bird Atlas 2007-11, Wetland Bird Survey and Breeding Bird Survey.
We are delighted that next month the BTO will update the dataset with records up to the end of 2019. As part of the update the datasets will be restructured and split between records on an Open licence (e.g. OGL) and those on a Shared licence (CC-BY-NC). Currently all records are on a Shared licence.
Reducing duplicate data
The BTO’s previous data provision included some essentially duplicate data. For example, the Breeding Bird Survey (BBS) data is collected on individual 200m transect sections, but the records are only referenced at the 1km square, which results in duplicate rows for species seen in more than one transect section. In this next submission of data, the records will be aggregated on both a spatial and temporal level. Spatially, the majority of records will be aggregated at 1km resolution, although some species will be aggregated at a lower resolution e.g. 10km. The temporal aggregation (i.e. by day or month) will depend on the individual survey. The full details of the levels of aggregation in the different surveys will be given in the dataset metadata.
If the BTO did not aggregate the data, their contribution of records to the NBN Atlas would increase by 91 million to 237 million. We believe that restructuring the records in this way will improve the usefulness of the datasets by continuing to add more information content, whilst reducing the size, by removing duplicate data points of less relevance to the majority of NBN Atlas users.
Once the dataset has been updated there will be a drop in the number of BTO-supplied records for the period up to the end of 2015 of 40 million records, affecting the overall number of records on the NBN Atlas.
Update of BTO’s non-avian dataset
Last week we updated the BTO’s non-avian taxa dataset with records up to the end of 2019. The dataset was split between records on an Open licence: Non-avian taxa (BTO/JNCC/RSPB partnership) and those on a Shared licence: Non-avian taxa (BTO+partners). The records were aggregated by species, record date and location as planned for the bird dataset.