An overview of bird surveys

 These guidelines propose a methodology to conduct bird surveys during the breeding and non-breeding season which takes a precautionary approach to quantifying bird behaviour. The scope of this method is designed to capture the full diversity of species using a given survey area, and provide an evidence base to inform the assessment of impacts and any additional specific surveys where necessary.

Key survey planning considerations

The key considerations when planning surveys for birds are summarised here with further detail provided on the relevant pages (which are linked to from these sections as well as being accessible from the menu above).

Are surveys actually required?

The first and perhaps most important question is to establish if any bird survey is actually required in order to determine  the impact of the project on birds.
A fundamental principle of these guidelines is that surveys of birds are always required unless you can robustly scope them out. 

Elements to consider include:

  • Review data collected during the scoping stage.
  • For projects that affect European designated Special Protection Areas (SPA) a screening assessment to inform a Habitats Regulation Assessment will be required but this may not actually require  bird survey to inform it.
  • Is there is sufficient and suitable desk study data to suggest that surveys are not required? For example, regular long-term Wetland Bird Survey (WeBS)  data may negate the requirement for surveys on a wetland site. When making this determination it is important to consider whether the available data is sufficiently recent and at the correct spatial scale.
  • Consider the Precautionary Principle as defined by 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.

Number of surveys

The default position of these guidelines is that a minimum of six survey visits should be carried out during the breeding season and four survey visits in the non-breeding season, unless a robust justification can be made as to why fewer or a greater number of visits are required.  

Factors to consider include:

  • Whether the site is small and of negligible importance to breeding birds,
  • The potential for the development or project to have a significant impact on breeding bird species is negligible.
  • The potential for significant impact to some aspect of avian site usage (i.e. the removal of nesting/foraging habitat) is high.
  • Important/priority species (such as species listed under Schedule 1 of the Wildlife and Countryside Act, bird species cited as interest features of designated sites, or Red and Amber listed by the Birds of Conservation Concern)  present on site, adjacent to the site or locations in the wider landscape connected to the site,
  • The proximity of the site to statutory and non-statutory designated sites with birds as a qualifying feature (or where qualifying features include habitats of importance to birds).

This link is for the Forestry Commission’s revised bird survey methods in relation to woodland creation.  


Survey timing

The breeding bird survey season is taken to be from mid March until early July and non-breeding bird season from November to February. The determination of the appropriate timing of surveys should consider a number of factors :

  • Whether any bird species have been identified that are likely to be more or less detectable at any given time of day or time of year due to their ecology (e.g. hobby nests late in the breeding season whilst nightjar are active after dark).
  • Whether any identified impacts of the project on avian usage of the site are likely to be seasonal and/or diurnal.
  • Whether any statutory and/or non-statutory sites identified in proximity to the site have seasonal variations to their qualifying features.

Data outputs

When planning bird surveys it is important to consider the data outputs that will be required. Typically for surveys of birds data outputs would include:

  • A  summary plan, including a clear map of priority species (species listed under Schedule 1 of the Wildlife and Countryside Act, bird species cited as interest features of designated sites, or Red and Amber listed by the Birds of Conservation Concern) and their site usage.
  • A list of secondary species (generally Green listed species of conservation concern).
  • An assessment as to how birds use the site and which areas of habitat and or features may be of particular importance.
  • A short interpretive report of key findings/priority species and important habitat(s) on site.

Data archiving

It is important to consider, at the planning stage, how collected data will be interrogated and the manner in which it should be stored to allow this. 

It is also important to ensure effective data archiving methods are in place to ensure the appropriate superseding of data, and ease of data retrieval and sharing (where appropriate client permission are received).