When sustainability in buildings is discussed, people often think about materials, energy use, CO2 footprints, and waste. Yet biodiversity rarely enters the equation. The report Wildlife and buildings: a technical guide to preserve and promote biodiversity in new construction and rehabilitation by SEO/BirdLife addresses how rich communities of fauna and flora interact with man-made structures and offers solutions to help them survive.
The publication focuses on birds, the so‑called other neighbors of buildings. Its goal is to guide architects, surveyors, public administrators, contractors, construction firms, owners, and any actors in the building sector to integrate wild species that use buildings as shelters or nesting sites into their planning and execution.
Buildings have increasingly become the last refuge for some species amid the degradation of natural shelter and nesting sites. Swallows, terns, kestrels, and many bat species rely on buildings and infrastructure for shelter and nesting opportunities.
One of the main threats to these vital habitats is the loss caused by rehabilitation, remodeling, or demolition of structures and the lack of suitable holes and cavities in new builds.
In response to energy renovation initiatives linked to the Upgrade, Transformation and Resilience Plan (PRTR) and evolving regulations demanding technological innovation, SEO/BirdLife produced the guide and launched a dedicated page about urban birds in buildings.
Advantages of traditional architecture
This guide offers two practical tools to help comply with biodiversity conservation rules related to breeding, sheltering, wintering, or resting birds in buildings. It also identifies funding streams tied to building energy rehabilitation projects.
It is important to recognize that destroying burrows and shelters breaches natural heritage and biodiversity protections. Such actions can delay projects or even trigger temporary suspensions and penalties for the responsible parties and owners.
SEO/BirdLife presents both constructive approaches and prefabricated options (including commercial nest units) to ensure nest presence on facades, partition walls, flat roofs, pitched roofs, and overhangs.
Traditional architecture generally offers more favorable conditions for biodiversity than contemporary designs, with a greater density of holes and safe nesting spaces. It often features protruding elements and cavities, as well as ventilated, organized, and well-protected spaces that are less accessible to the outside world than modern buildings, according to the manual.
Thus, the gradual replacement of traditional construction methods reduces the opportunities for biodiversity. SEO/BirdLife highlights several points to consider during interventions:
Interventions on the structure. Work plans should account for the presence of nests and shelters, their potential locations, and adjustments to elements on flat or pitched roofs, eaves, and air chambers, as well as other structural components that could affect nesting opportunities.
Interventions on the façades. Special attention should be given to holes, cracks, and potential access to interiors or rooms.
Interferences with nearby elements such as trees or fences. Where trees are close to a building, the existence of nests or tree cavities on trunks should be assessed, and nest boxes or shelters can be added to support other bird and bat species. Existing walls or partitions may be adapted, especially if masonry is involved, to the building’s periphery.
For new constructions and integrated rehabilitations, a holistic analysis should consider all the above aspects from the outset.
Coexistence with urban fauna
SEO/BirdLife regards it as essential to adapt studies to the phenological calendar of birds and bats. This means evaluating the building as a breeding, sheltering, or hibernation site with seasonal sensitivity.
The spring and summer breeding period is the most sensitive for birds. Therefore, autumn and winter are the preferred windows for field studies, when the presence of summer migratory species is diminished.
If bats inhabit a building, field studies should generally avoid the peak breeding period from April to July and the hibernation period from November to March. In those cases, the optimal window in Spain is late summer to early autumn.
When dates cannot be shifted to align with the phenological calendar, preventive measures can still be taken. Physical barriers such as nets, boards, or other protective devices can deter nesting during sensitive intervals, while offering artificial nests and shelter boxes nearby as temporary compensation. This approach is described by the NGO as a viable mitigation strategy.
The guide also includes a section on Precautions for coexistence with urban fauna, offering practical solutions for events such as excessive nest weight, fecal buildup, noise, or tile displacement. Among recommended measures are the installation of devices to prevent droppings from entering rain gutters, the use of metal structures to transfer nest loads to the building’s vertical elements in a controlled way, and ensuring adequate acoustic insulation. It also advises minimizing wild pigeon presence by limiting shelf-like nest areas and, where possible, maintaining sloped surfaces and avoiding holes larger than ten by ten centimeters.
Wildlife and buildings is a practical guide produced by SEO/BirdLife. It does not contain external links within the text but provides attributed references to support its claims.
The guide ends with a note on a broader conservation mindset and a call to balance energy efficiency with the needs of urban wildlife, supported by field observations and expert recommendations from SEO/BirdLife.
Further details and the full guide can be cited from SEO/BirdLife’s publication on wildlife and buildings through their official materials, with attribution to the organization for the concepts discussed.