Surveys for breeding birds

While there are a number of existing approaches to surveying birds in the breeding season, including territory mapping options such as the Common Bird Census (CBC) (Marchant, 1980) and citizen science approaches such as the Breeding Bird Survey (BBS) run by the British Trust for Ornithology (BTO), these methodologies were/are designed to monitor long-term trends in bird populations at a national level. As such they are broadly unsuitable for fine-scale applications, such as ecological impact assessments, which are often undertaken in a single season. As a result, there is an absence of a clear methodology for undertaking ornithological surveys in the bird breeding season. It is the purpose of these guidelines, to address this gap.

Note – the guidelines try to avoid the use of the term Breeding Bird Survey (BBS) as this has already been adopted by the BTO. The methodology used in the BTO’s BBS is generally NOT suitable for assessing site value. 

The guidelines are loosely based on the CBC technique, making use of repeated visits in a single season (albeit fewer visits compared to CBC recommendations) and some simplified elements of territory mapping. However, where CBC asks exactly how many individuals are nesting (or holding territory) in a given area, the method presented here seeks to measure in what way, if at all, a given area is important to avian diversity, what species could potentially be breeding and, therefore, what the impacts of the project or development being considered are likely to be. When gathering survey information, be mindful of the Precautionary Principle as defined by the Chartered Institute of Ecology and Environmental Management (CIEEM):

The evaluation of significant effects should always be based on the best available scientific evidence. If sufficient information is not available further survey or additional research may be required. In cases of reasonable doubt, where it is not possible to robustly justify a conclusion of no significant effect, a significant effect should be assumed. Where uncertainty exists, it must be acknowledged in the EcIA”.

For the purposes of surveys of breeding birds it is necessary to understand not only what bird species are potentially present within the survey area, but also the conservation value of its breeding bird assemblage, in both a local and wider context, as well as how the survey area is used by birds in the breeding season.

It is intended that these guidelines will provide an approach that can be consistently implemented across the ecological consultancy industry, and it is therefore, applicable to the collection of ornithological data in both terrestrial and freshwater habitats. However, it is recognised  that some deviations may be required for highly specialised applications (e.g. where likely significant effects are anticipated in respect of Special Protection Areas or Ramsar sites) and as such the guidelines are designed to encompass some degree of flexibility to site and species-specific survey planning. It is therefore recommended that these guidelines are treated as a baseline protocol and any required variations are appropriately justified.

This web resource will undergo future updates to enable it to cover a range of survey methods. However, this initial launch has focused on providing a standard set of survey guidelines for surveys of breeding birds. The focus is on surveys for breeding birds, as this is perhaps the most frequent survey type used, yet the exact methods used often vary greatly between ecological consultancies.

The Scoping page of these guidelines includes a bird survey scoping flowchart, to help inform survey decisions.