Swift Nest Site Conservation: Practical Guidance
Loss of nest sites in renovated buildings is the leading cause of swift population decline in the UK and Europe. This page provides practical guidance on protecting existing sites and creating new ones.
Why Nest Sites Matter
Common swifts nest almost exclusively in cavities in buildings—typically under roof tiles, in holes in fascia boards, or in gaps behind barge boards in older properties. They are highly site-faithful, returning to the same nest cavity year after year for up to two decades. When buildings are renovated without provision for swifts, colonies are eliminated permanently. Population recovery depends critically on maintaining existing sites and creating new ones in sufficient numbers to offset losses from renovation.
Legal Protection of Swift Nests
Swift nests in use (or recently used) are protected under the Wildlife and Countryside Act 1981. Destroying or damaging a nest, or intentionally disturbing nesting swifts, is a criminal offence. However, enforcement is difficult and planning compliance mechanisms often fail to protect sites adequately. Property owners, builders, and architects need proactive education about swift nest identification and legal obligations before building works commence during the swift season (typically May–August).
Identifying Swift Nest Sites
Swift activity around a building during May–August—particularly screaming parties gathering in the evening and birds entering cavities—indicates nest sites. Nest sites are best surveyed between June and July when activity is at maximum. The Swift Conservation website provides standardised survey methodology. Property owners can submit survey records to the national swift mapping database, creating a baseline for monitoring and informing planning applications.
Swift Bricks: Design and Installation
Swift bricks are purpose-built nest cavity units designed to be integrated into external masonry walls during construction or renovation. The RSPB, Swift Conservation, and BTO have developed specifications for effective swift bricks. Key design features include: a small oval entrance (approximately 65mm x 28mm), sufficient internal cavity depth (minimum 280mm), rough interior surfaces for grip, and insulating materials preventing temperature extremes. Nest boxes can also be mounted externally under eaves.
Planning Policy and Developer Guidance
Planning policies in an increasing number of local authorities (including Brighton, Norwich, and parts of London) now require swift bricks in new developments. The Town and Country Planning (England) 2023 biodiversity net gain requirements create new incentives for biodiversity features including swift nest sites. Developers, architects, and planning authorities benefit from clear guidance specifying swift brick numbers, positions, and orientation appropriate to building type and location.
Retrofitting Nest Sites
Existing buildings can accommodate swift nest boxes retrofitted under eaves, in gable ends, or high on walls. Optimal placement: south-facing or east-facing, at height (above 5m from ground), under eaves or soffits, and close to existing swift activity. Calling systems (playback of swift calls during the swift season) can attract prospecting swifts to investigate new nest boxes. Colony establishment through nest boxes can take 1–3 years but once established, sites are used reliably for decades.
Community and Volunteer Involvement
Swift conservation relies on community networks: Swift Local Action Groups (SLAGs) operate across the UK, surveying local populations, engaging property owners, lobbying planners, and installing nest boxes. Citizen science monitoring data from these networks feeds into national population assessments. Schools near swift colonies provide opportunities for environmental education. Community ownership of swift conservation creates sustained monitoring and advocacy beyond what statutory conservation bodies alone can deliver.
Summary
Swift nest site conservation is achievable through planning policy requirements for swift bricks in new development, proactive protection of existing sites during renovation, retrofitting of nest boxes in occupied areas, community-led monitoring, and public education about swift identification and legal protection. Effective swift conservation is a practical urban biodiversity action within reach of every local authority, developer, and property owner.