Breeding bird survey

Every wild bird in the UK is protected under the Wildlife and Countryside Act 1981. Deliberately disturbing nesting birds, destroying active nests, or taking eggs are criminal offences regardless of whether the disturbance is intentional. For development sites, the practical implication is that vegetation removal, building demolition, and ground clearance must not take place when nesting birds are actively using the site unless the necessary assessment has been carried out and appropriate measures are in place.

Certain species carry additional protection under Schedule 1 of the Wildlife and Countryside Act, including birds of prey such as peregrine, merlin, and barn owl, as well as other species such as stone curlew, red kite, and kingfisher. Disturbing a Schedule 1 species at or near its nest during the breeding season is a more serious offence and can trigger a requirement for a European Protected Species licence.

A breeding bird survey identifies what is present, what level of protection applies, and what the development must do to remain on the right side of the law.

A breeding bird survey uses a territory mapping methodology adapted from the Common Bird Census technique and aligned with CIEEM guidance. It is specifically designed to assess the ecological value of a site for breeding birds and the potential impact of development, rather than to monitor population trends across the wider landscape.

The ecologist walks a pre-planned transect through all the habitats on the site, starting within half an hour of sunrise when bird activity is highest and completing the survey by mid-morning before detection rates drop. Every bird encountered is recorded by sight or sound, using standard BTO species codes, and its location and behaviour are plotted onto a detailed site map. Evidence of breeding activity is noted for each species: singing males, carrying food or nesting material, alarm calling, or the direct observation of nests, eggs, or dependent young.

Across the full set of visits, the distribution of records for each species is used to identify probable and confirmed breeding territories. The territory map produced from this data is the evidence base for the impact assessment.

The number of visits depends on the size and complexity of the site and the level of detail the planning authority requires. For most planning surveys, a minimum of three to four early-morning visits are carried out across the breeding season, with visits distributed to cover the early season, the peak breeding period, and the late season.

The early visit, in April or early May, captures resident species that begin nesting early and early-arriving migrants. The late visit, in late May or June, captures later-arriving species and confirms breeding for species that peak later in the season. At least four weeks should separate early and late visits to ensure the data reflects genuine seasonal variation rather than a snapshot of a single point in time.

For sites with potential for early-nesting species such as raptors, corvids, or owls, a February or early March visit may be required before the core season begins. For species active at dusk or dawn such as nightjar, barn owl, or grasshopper warbler, a dedicated dusk or dawn visit may be added to the programme.

For larger sites or where a full EcIA chapter on birds is required, up to six visits may be needed to produce data of sufficient resolution for the impact assessment.

A separate but closely related service is the pre-clearance nest check: a targeted visit carried out immediately before vegetation removal or demolition begins to confirm whether any active nests are present in the material to be cleared.

Pre-clearance surveys are good practice for any clearance work during the breeding season, from March to August, and are required as a condition on many planning consents. They do not replace the baseline breeding bird survey but they ensure that clearance can proceed without breaching the protection that applies to active nests.

Where an active nest is found, clearance of that specific area must be deferred until the nest is no longer in use. The ecologist advises on the extent of the exclusion zone and the likely timescale before the nest can be cleared. For most species this is a matter of weeks; for Schedule 1 species it may require formal advice from Natural England before any works can proceed.

The territory map and species records produced by the breeding bird survey feed into several downstream uses.

In the ecological impact assessment, the survey data informs the significance of the impact of the development on each species, the level of mitigation required, and the residual effect once mitigation is in place. Species of conservation concern, those on the Red or Amber lists of Birds of Conservation Concern, carry greater weight in this assessment than common, widespread species.

In the biodiversity net gain calculation, birds contribute to the baseline through the habitats they depend on rather than being directly valued in the metric. However, the survey data informs the habitat condition assessment and the design of enhancement measures that benefit birds as part of the wider BNG plan.

For pre-commencement conditions on a planning consent, the survey data supports the preparation of an ecological management plan or construction ecological management plan that sets out timing restrictions, clearance protocols, and habitat creation commitments.

Breeding bird survey costs depend on the size of the site, the number of visits required, and whether the survey is standalone or part of a broader ecological assessment. Sites requiring dusk visits for specialist species or extended coverage for Schedule 1 species are priced accordingly.

Surveys must be booked well in advance of the season to allow the transect route to be planned and visits to be scheduled across the appropriate parts of the breeding season. To get a quote, provide us with your site address, a description of the habitats present, and an indication of what the survey needs to support. We will confirm the visit programme and provide a fixed price.