None of the UK's biggest cities have policies in place to protect birds from deadly strikes with buildings in their boroughs, exclusive Dezeen research has found.
Freedom of Information requests to the 33 local authorities in London and the councils responsible for 10 other major UK cities also revealed that none have ever carried out an assessment of bird-window collisions in their areas.
This is despite the British Trust for Ornithology's (BTO) alarming estimation that up to 100 million birds crash into the windows of buildings in the UK each year, with one-third of these birds dying as a result.
David Noble, a scientist who is investigating the issue of window-strike risks for the BTO, warned that building collisions could be accelerating the decline in bird numbers in the UK.
"UK bird numbers are declining overall and although evidence is lacking, collisions could be a contributing factor for any particularly vulnerable species, whether urban residents or nocturnal migrants or due to some other factor," he told Dezeen.
The lack of council-led assessments reflects a wider shortfall in data on bird collisions, Noble added.
"We know from experience and through ring recoveries that bird-glass collisions occur but the magnitude of mortality and evidence for population-level impact in the UK and in Europe is little-studied and remains largely unknown."
Bird-friendly legislation "would be both helpful and precautionary"
Noble called for legislation to require those working in the built environment to deliver bird-friendly buildings.
"Regarding policies to require architects and builders to implement bird-friendly windows and glass, moving in that direction would be both helpful and precautionary," he said.
Through their planning policies, which are informed by national government guidance, councils are able to control new development in their areas.
Councils in the UK have duties set by the governments of England, Scotland, Wales and Northern Ireland to consider the protection of biodiversity in their planning policies – but this guidance is focused on ensuring new developments do not affect habitats and not on preventing building strikes.
The Local Government Association, which represents councils in England and Wales, said it was not able to comment on Dezeen's findings.
The Department for Levelling Up, Housing and Communities, which oversees planning policy in England for the UK government, did not respond to a request for comment.
"Change can and should come from within the industry"
Worldwide, it is estimated that collisions with buildings cause billions of bird deaths a year.
This is because birds can mistake windows for continued space or become disorientated by interior lighting that shines through them at night.
However, research suggests these fatalities can be minimised through simple measures such as opting for fritted or patterned glass on a facade, which is one of the most common ways to make glass on buildings visible to birds.
In response to Dezeen's findings, senior vice president of animal rights organisation PETA Colleen O'Brien said that legislation and assessments could help save the lives of birds, but that architects should not wait for these to design bird-friendly buildings.
"Much-needed legislation requiring assessments of the impact of buildings on wildlife would save millions of animals' lives, but change can and should come from within the industry," she told Dezeen.
"Many architects are already embracing masking films, frits, ultraviolet patterns, and other design elements that prevent birds from crashing into reflective windows, and PETA is calling for bird-friendly glass to become the new industry-wide standard."
London Plan suggests impact assessment of tall buildings
While no council contacted by Dezeen currently has any bird-friendly guidelines in place for new development, the London borough of Waltham Forest said it is developing a new local plan with a policy relating to the development of tall buildings, in which bird strikes are highlighted.
The proposed Policy 57 notes that where high-rise buildings are constructed, the "harmful environmental impacts in relation to wind movement, solar glare, microclimatic conditions, air, noise and light pollution and bird and bat strikes" should be avoided.
This clause echoes Policy D9 of the London Plan 2021, which was flagged by the London boroughs of Ealing, Havering, Hillingdon and Bromley as the only planning policy guidance relevant to bird strikes.
Released in 2021, the London Plan is a strategy developed by mayor Sadiq Khan to offer a framework for how Greater London should develop over the next 20-25 years. Policy D9 suggests that the impacts of tall buildings on birds "may need to be taken into consideration" when in development.
"For example, the impact of new tall buildings in proximity to waterbodies supporting notable bird species upon the birds' flight lines may need to be considered," reads the supporting text.
However, both the London Plan and the emerging local plan of Waltham Forest do not explicitly prevent potentially harmful buildings from being constructed or offer suggestions for how they can be made more bird-friendly.
Both these policies also only refer to the development of tall buildings in the boroughs. However, according to Melissa Breyer, a volunteer for New York City wildlife charity NYC Audobon, building heights are not a key factor in bird deaths.
"The main culprit is definitely a reflective surface," she told Dezeen earlier this year, indicating that even low-rise buildings can be hazardous to birds.
"Almost all of these [bird strikes] are happening at the treeline because that's where the habitat is reflected," she continued.
Bird-friendly legislation more stringent in US
Unlike in the UK, city officials across the US have begun introducing more stringent guidelines to prevent bird collisions with buildings as awareness of the issue increases.
This includes Local Law 15 in New York City, a bill introduced in 2019 that requires the surfaces of new glass buildings over 23 metres (75 feet) tall to be patterned to make them more visible to birds.
However, existing glass buildings in the city continue to pose problems for migrating birds. In 2021, Breyer made headlines when she collected the corpses of over 200 birds that had flown into buildings at the World Trade Center.
In a single day, she found 226 carcasses from the pavements around the 3 World Trade Center tower designed by Rogers Stirk Harbour + Partners and 4 World Trade Center tower by Fumihiko Maki.
At the time, Breyer said she identified many more, but that they were "inaccessible, or too mangled to collect".
Elsewhere, a bill was filed in Washington DC calling for new buildings in the city to be designed with products that deter birds from colliding with their glass surfaces.
Since being proposed earlier this year the bill has been widely supported in the city, according to the local organisation City Wildlife.
Its president Anna Lewis told Dezeen that the bill "will be highly effective" in solving the problem of bird collisions.
"We need to appreciate that these collisions are not random, that our building designs are causing them, and that there are simple fixes that can prevent these tragic collisions," she said.
Below is the data for each of the 43 UK councils surveyed, listed in alphabetical order:
Belfast
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Birmingham
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Bristol
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Cardiff
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
City of London
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
City of Westminster
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Edinburgh
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Glasgow
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Leeds
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Liverpool
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Barnet
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Barking and Dagenham
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Bexley
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Brent
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Bromley
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Only relevant planning policy is D9 of the London Plan.
London Borough of Camden
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Croydon
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Ealing
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Only relevant planning policy is D9 of the London Plan and planning guidance published by Natural England on 14 January 2022.
London Borough of Enfield
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Hackney
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Hammersmith and Fulham
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Haringey
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Harrow
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Havering
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Only relevant planning policy is policy D9 of the London Plan.
London Borough of Hounslow
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Hillingdon
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Islington
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Lambeth
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Lewisham
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Merton
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Newham
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Redbridge
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Richmond upon Thames
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Southwark
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Sutton
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Tower Hamlets
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
London Borough of Waltham Forest
Policy 57, Tall and Taller Buildings in part one of the council's proposed local plan includes the issue of bird strikes against tall buildings in the borough.
Under the proposed plan, tall buildings will only be supported where they are designed to prevent bird strikes, as well as other criteria such as overheating and light pollution.
However, this plan is currently in the process of examination and may be modified.
No record of assessment by the council of bird deaths caused by collisions in the area.
However, the council said the issue of bird strikes is addressed on a site-specific basis in the assessments for new developments. For example, the Blackhorse Lane Masterplan framework considers bird migration routes.
London Borough of Wandsworth
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Manchester
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Royal Borough of Greenwich
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Royal Borough of Kensington and Chelsea
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Royal Borough of Kingston upon Thames
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
Sheffield
No record of specific policy or guidance in place concerning the issue of bird strikes in the area.
No record of assessment by the council of bird deaths caused by collisions in the area.
The main photo is by Viveca Morris via Wikimedia Commons.Â