4. Taxa considered by BBRC

4.1    Introduction

In broad terms the BBRC assess the sightings of rare bird taxa (species or sub-species) in Britain.

Each year at the AGM we will review the levels of occurrence for those taxa currently assessed by the Committee, and those taxa NOT currently assessed by the Committee but which may be close to being considered ‘rare’. Data used will come from the BBRC’s own archive of records, and also from information published by birding information services, and in particular the Scarce Migrants report published in British Birds.

Any changes will be announced in British Birds and via birding information services. They normally will come into effect on January 1st of the following year, but can be back-dated to the start of the current year.

4.1.1 Definition of a BBRC Rarity

The starting point for defining a national rarity is either 100 or fewer individuals in the most recent ten-year period, or ten or fewer individuals in at least seven of the last ten years. Any taxon that meets, or is close to, either of these criteria, will then be considered for inclusion as a BBRC rarity.

The Committee will also consider other factors such as population trends, distribution changes and identification issues.

4.1.2 Removal of a BBRC Rarity

All taxa currently assessed by BBRC will also be looked at, to check they remain rare. The starting point for removing a national rarity is either more than 100 individuals in the last ten years, or more than ten individuals in at least seven of the last ten years. Any taxon that meets, or is close to, either of these criteria, will then be considered for removal.

The Committee will also consider other factors such as population trends, distribution changes and identification issues.

Once a taxon has been dropped as a BBRC rarity it would not normally be reinstated, even if the criteria of Section 4.1.1 are met, until 10 years have passed.

4.1.3 Helping Counties

When a species/taxon is no longer considered rare, then assessment of those records will normally be undertaken at a County level. If a County Rarity Committee feels they do not have sufficient expertise to assess a difficult taxon, or maybe a specific record, then BBRC will provide advice on such records, if asked.

4.2 Taxa considered by BBRC

4.2.1 Introduction & Species considered

BBRC follow “The British List” as published by the BOURC, and as amended by subsequent Reports published by BOURC.

As well as species given in the British List we accept submissions for some indeterminate groups of species & sub-species (see Section 4.2.3 & Appendix IV).

A full list of the taxa considered by the committee is published on the BBRC website.

In addition any species or sub-species not currently on the British List would be considered by BBRC. This would therefore, if accepted by both BBRC & BOURC, become a First for Britain and as such should meet the requirements detailed in Appendix III. The submitter should give detailed reasons why they think the record was the species/sub-species claimed, explaining the identification features used. They should also give reasons why the record is not likely to be categorised as an escape, and can therefore be added to the British List by BOURC.

4.2.2 Sub-species considered

Note that a sub-species can be considered rare even if the full species is not considered rare. With such sub-species, field or in the hand identification of a vagrant individual has to be considered possible with a high degree of confidence.

Furthermore the BBRC encourages identification to a sub-species level for species that are a BBRC rarity in their own right

4.2.3 Indeterminate Species/ Sub-species pairs or groups

In a few cases, the Committee considers and publishes indeterminate records of pairs or groups of rare species or subspecies, which are considered particularly difficult (or impossible) to separate under present knowledge, or where the identification criteria may not be always possible to see in the field (see Appendix IV).

These indeterminate pairs and groups are reviewed at the AGM.

Note that where identification criteria for subspecies are clearly established and which are usually possible to see in the field, then Indeterminate records will not be published and will be considered Not Proven.

Subspecies taxonomy is somewhat fluid, much variation is clinal and identification criteria are often less clearly defined than those for species. BBRC will therefore remain flexible on how it accepts and publishes records of rare subspecies, retaining the option to attribute a bird to a pair/group wherever appropriate. However, the indicative list of potential subspecies pairs/groups at Appendix IV may be useful. It includes those already published and those listed in Stoddart. 2016. Rare subspecies in Britain. British Birds 109: 46-58.

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