All birds in the UK are protected by the Wildlife and Countryside Act 1981. This makes it an offence to intentionally injure, kill or take any native bird, including its nest or eggs. As a result, it is often a legal requirement within planning applications for development sites to carry out bird surveys. These will establish what species are present as well as monitor whether the development is having, or is likely to have, any impact on their numbers.
The type of survey used will depend on the type of habitat that the site covers and the potential species present.
Breeding Bird Surveys (BBS)
The Breeding Bird Survey is one of the commonest ornithological surveys used. It provides estimates of the density and locations of breeding species within a survey area with a methodology developed by the British Trust for Ornithology (BTO).
A minimum of three visits are made, with the first ideally in March and the last in late June, and with gaps of at least four weeks between each visit. This ensures that the full range of breeding species, from early residents to later migrants, are not missed.
Surveyors walk two parallel transects of 1 kilometre, 500 metres apart, mapping all birds seen and heard and recording their behaviour.
Territory Mapping Surveys
Before the BTO adopted BBS, they used a territory mapping approach called the Common Birds Census. Their focus was on farmland and woodland plots. Although the BTO no longer uses this method, it can be useful as it is a lot more intensive than BBS.
Plot sizes vary depending on the habitat, but the aim is to cover each plot on foot evenly and thoroughly, recording the location and movement of each bird seen or heard. Behaviour and any nest presence is also recorded. Ideally, ten complete visits are made to each plot between mid-March and late June, and at the end of the season, an ecologist will use the data to ascertain how many individual territories are held.
Winter Bird Surveys
This commonly used survey has some similarities with BBS methodology, using transect walks to plot species. One to two visits are made per month between October and March to provide information about the species present, numbers and densities. Behaviour is also often monitored so that preferred feeding or roosting sites can be ascertained.
These can be particularly important on sites with habitats that support large numbers of winter migrants, such as coastal areas. They can also be critical if a site is suspected of supporting declining winter species, such as fieldfare.
Intertidal Bird Surveys
Due to the importance of intertidal zones to wintering birds, proposed developments that include, or are adjacent to them, require surveys to assess any potential impact on birds using the area. Intertidal surveys are typically carried out between September and March if the area is used by birds on migration. If not, they may just focus on the core months of November to February.
Surveys used include monthly core, low-tide, or through the tide cycle counts (TTTCC) depending on the habitat type and likely birds present. All of these are on a ‘look-see’ basis which involves scanning the whole area and counting the number of birds of each species present. Night surveys using thermal imaging equipment are also a possibility.
Vantage Point
Vantage point surveys were designed to monitor the flight paths and flight frequency of species potentially affected by wind farms. Depending on the likely species to use a site, the timing of the surveys will vary; summer for potential breeding species, winter for areas know to support wintering birds.
Vantage points that cover the whole survey area are pre-selected, with target species monitored will usually be raptors, wildfowl or waders. The survey’s duration will depend on the target species, but the aim is to determine how a potential windfarm will impact flight paths, along with the potential for collisions.
Upland Breeding Wader Surveys
Carried out between early April and late June, these surveys are designed to monitor upland wader populations. Species surveyed include golden plover, dunlin, curlew, redshank and oystercatcher.
Surveys use the Brown and Shepherd methodology which involves timed observations made while travelling pre-determined routes through 500 x 500 metre grid squares. A minimum of two visits are made during the breeding season and the surveys are useful for windfarm projects, upland farming and for upland road projects, such as the dualling of parts of the A9 in Scotland.
Species Specific Surveys
Schedule 1 of the Wildlife and Countryside Act affords certain bird species even greater protection than the general legislation, and it is only permitted to disturb these during the breeding season with a special licence.
If there is potential for a Schedule 1 species to be breeding on a project site, a species-specific survey will need to be carried out under licence to determine their presence and assess the site’s impact, along with the need for any mitigation measures.
We are full Schedule 1 licence holders here at Purple Plover.