Winter bird surveys methodology and benefits explained
The spring and summer seasons are the busiest periods for ecologists, with activity peaking throughout May, June, and July. However, wintering bird surveys are still very important in offering insights that can significantly influence planning, conservation, and compliance outcomes.
At Thomson Environmental Consultants, we have decades of experience in conducting wintering bird surveys across a range of habitats. Here, we take you through what wintering bird surveys are, why they matter, and when they should be carried out.
What are wintering bird surveys?
Wintering bird surveys are structured ecological assessments that monitor bird populations and activity during the non-breeding season, typically from October through March in the UK. These surveys are designed to record species presence and abundance, habitat use and behaviour, roosting locations, and movement patterns. Coordinated efforts (eg, British Trust for Ornithology (BTO) Wetland Bird Surveys (WeBS) are also used to monitor national populations of shorebirds.
Winter bird surveys are particularly important for migratory species that breed in northern Europe, Russia, or the Arctic and spend the winter in milder climates such as the UK. They are especially relevant in wetlands, estuaries, farmland, coastal regions, and managed landscapes, where food resources and shelter can attract thousands of wintering birds.
Why are wintering bird surveys important?
1. Legal and policy compliance
One of the primary drivers for wintering bird surveys is compliance with environmental legislation. Many bird species are protected under:
- The Wildlife and Countryside Act 1981.
- The Conservation of Habitats and Species Regulations 2017.
- UK Biodiversity Action Plan (UK BAP) priorities.
- The Birds Directive and Ramsar Convention (for wetland areas).
Where development is proposed near sensitive sites, such as Special Protection Areas (SPAs), wintering bird data are essential to inform Habitat Regulations Assessments (HRAs) and Environmental Impact Assessments (EIAs).
2. Conservation and stewardship
Not all wintering bird surveys are driven by development. NGOs, conservation charities, landowners, and public bodies commission these surveys to guide habitat management, stewardship schemes, or long-term monitoring projects.
Accurate survey data helps inform:
- Management of designated sites.
- Agri-environment schemes (for example, Countryside Stewardship).
- Reserve design and zoning.
- Predator control decisions.
- Habitat restoration priorities.
What are some of the key wintering bird species of concern?
Some of the UK’s most vulnerable bird species require winter monitoring. These birds “wander” more widely, and can form larger aggregations away from breeding grounds:
- Waders (curlew, black-tailed godwit, golden plover, knot, dunlin).
- Waterfowl (pink-footed goose, teal, wigeon, whooper swan, pintail).
- Farmland birds ( corn bunting, skylark, yellowhammer).
- Raptors (hen harrier, merlin, short-eared owl).
- Thrushes and finches (redwing, fieldfare, brambling).
- Early breeders: Depending on habitat, some specially protected (Schedule 1) birds can nest before the ‘main’ breeding season. Although a preliminary ecology survey should inform this, wintering surveys can also detect nesting behaviour for such species.
Many of these species travel long distances and rely on UK habitats for overwintering. Declines in these populations are a growing conservation concern. The availability of accurate wintering survey data is vital in decision-making to help reverse these trends.
Find out more about bird survey services here.
When are wintering bird surveys conducted?
Wintering bird surveys are typically conducted throughout October to March, with peak activity in December to February. Survey timing is crucial to account for migratory arrivals, mid-winter abundance, and pre-migration departures, and exact survey design is based on the target species, dictated by habitat and geographical location. Most sites require at least four monthly visits, although higher-value sites or those under planning scrutiny may require fortnightly or weekly surveys.
What are the methods used for winter bird surveys?
Depending on the habitat and species expected, wintering bird surveys may involve:
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- Vantage point (VP) watches: Fixed observation points, particularly useful for large open areas (e.g., intertidal areas) and raptor monitoring.
- Transects: Systematic walking routes used to cover farmland, grassland, or mixed habitat sites.
- WeBS methodology: For wetland and waterbird surveys, aligning with the BTO WeBS protocols.
- Terrestrial roost surveys: Conducted at dawn or dusk to observe bird movements to and from communal roost sites, e.g., in woodlands.
- High tide roost surveys: VPs or transects (or a combination) conducted during high tide to identify communal shorebird roosts.
- Flight line mapping: Especially important for wind energy projects and collision risk modelling.
- Nocturnal survey: The above methods may be supplemented by nighttime surveys using thermal or infrared night vision aids (shorebirds in particular forage at night to maximise energy intake)
- Remote sound recording: An increasingly used method, gaining additional data to supplement direct surveyor effort. Sound recordings can be analysed by ear and through sonogram analysis.
Data is recorded on species, numbers, behaviour, and precise locations (usually with GIS mapping), with careful notes taken of weather, disturbance, and visibility.
What can winter bird survey data be used for?
Collected data can be analysed to identify:
- Species richness and diversity.
- Peak counts and population estimates.
- Use of the site by key species.
- Habitat preferences and areas of peak activity.
- Potential constraints or impacts from the proposed development.
These outputs are then contextualised against national and regional population trends.
Our recent work
Development project support in Wales
We supported a residential developer in Wales with winter bird surveys to assess the value of a series of grassland fields which form part of the Local Development Plan. Monthly visits between November and February, including a dusk survey for species such as owls and waders, confirmed winter use by four species listed on Schedule 1 of the Wildlife and Countryside Act and seven species on the Red List of Birds of Conservation Concern. By identifying areas of highest value to birds during winter, our recommendations were designed to ensure sustainable development through retaining habitat where possible and offsetting lost areas nearby, in line with Welsh planning policy.
Port development support in Greater London
We supported a port developer with wintering bird surveys of habitat compensation sites, and functionally linked the land of the Thames Estuary SPA and Ramsar, as part of post-development monitoring. Monthly high and low tide surveys monitored wintering bird populations for 24 key species and highlighted roosting locations. The data collected is used to monitor populations relative to pre-development numbers, as required by planning consents.
Visit our recent bird survey projects here to find out more about our work.
Challenges and best practices when conducting winter bird surveys
Wintering bird surveys can be logistically demanding. Key challenges include weather constraints, in which fog, heavy rain, and high winds can limit survey reliability. Reduced daylight and dates, often dictated by tide times, can also present challenges. In some cases, sites may be flooded, frozen, or otherwise inaccessible.
Surveys must avoid flushing or stressing overwintering birds, and it is important to minimise disturbance where possible.
The best practices to overcome these challenges include:
- Planning flexible survey windows to allow rescheduling.
- Liaising with landowners for access and permissions.
- Using experienced ornithologists, high-quality optics, night vision aids, and sound recording equipment.
- Surveyors with off-road driving capabilities and appropriate vehicles (surveying from vehicles can reduce disturbance and yield improved datasets).
- Employing digital tools (e.g., GIS, GPS, drone imagery) for mapping and data validation.
Why clients should invest in wintering bird surveys
Carrying out winter bird surveys ensures your project supports, rather than harms, vital winter habitats. Winter bird surveys can help to identify constraints early and avoid surprises later in the planning process. Early engagement prevents delays, redesigns, or legal challenges. They can also allow you to use data to support agri-environment grants and offsetting schemes, which may not be development-related.
Additionally, investing in winter bird surveys helps to strengthen your reputation and demonstrate your commitment to environmental compliance.
Get in touch today to find out more
Interested in discussing a wintering bird survey for your project? Contact our friendly and experienced ecology team today. We offer:
- Free initial consultations.
- Fixed-price quotes.
- Experienced ornithologists with extensive UK and European experience.
- Survey programs tailored to your site, timeline, and regulatory needs.
Winter might not be the busiest season in ecology, but it’s one of the most revealing. Birds are an excellent indicator of habitat quality, conservation value, and sensitivity. Through wintering bird surveys, we have the chance to identify constraints and respond accordingly. Get in touch with us today to find out how we can help.
