Many bird and bat species traditionally live in human dwellings. This is not limited to the classic example of swallows on farmhouses. They also regularly colonize modern buildings and technical structures such as bridges or underground car parks.
All native bat species and building breeders such as swifts, swallows, house sparrows and kestrels are protected under national and European law. This protection covers both the individuals (and in the case of birds also their nests) and their breeding and resting places (habitats). These can be nests, for example, but also regularly used roosts and, in the case of bats, especially breeding, summer and winter roosts.
The protection of habitats only ends when they have finally lost their function. This means, for example, that house martin nests are protected even if the animals are in Africa during the cold season. They return to their traditional breeding grounds in spring and use their nests for many years in a row.
What should be considered when working on buildings
In general, there is always a risk that individuals of protected species will be killed and their reproductive stages and habitats destroyed during demolition, renovation or other work on buildings. The animals could also be disturbed, which could lead to them giving up breeding. The legal requirements (in particular the access bans in accordance with Section 44 (1) BNatSchG) must therefore be observed for every planned intervention. This responsibility lies with the intervening party (developer, companies, citizens, etc.), who must therefore clarify the risks in advance, if necessary with expert assistance (e.g. expert opinion).
If violations of species protection cannot be ruled out, suitable avoidance and compensation measures must be developed. It is advisable to commission an expert or specialist agency to implement these measures. As part of ecological construction monitoring, a suitable schedule for carrying out the work can be drawn up in order to preserve nesting sites for building breeders and bat roosts or, if necessary, to provide compensatory roosts with official approval.
The implementation of effective replacement and avoidance measures generally requires an adequate time frame, as they can only be carried out at certain times of the year. However, it is still possible to deal with the issue smoothly, even in the case of extensive renovations, if all parties involved (building owners, authorities such as environmental agencies/lower nature conservation authorities, experts, but also nature conservation organizations) work hand in hand on solutions at an early stage.
Worth knowing:
Bat roosts and nesting sites of building-breeding birds often go unnoticed, as they are usually well hidden in attics or cellars, in cavities in the eaves, under fascia boards, behind shutters or in cracks and niches in the façade. Usually 1-3 cm wide crevices in spacers, cracks, fissures or facings are sufficient as hiding places. Many species are loyal to their breeding sites and return to them again and again.
Species profiles, nesting and breeding season calendar:
Swift: Migratory bird, arrival in the breeding area from mid-April, departure from the beginning of August, loyal to breeding sites. Breeding sites mostly under the roof, often in the eaves area. Need a free approach. Scaffolding can prevent entry, which is why it must not be erected in front of breeding sites from mid-April.
House sparrow: Year-round bird, breeding season from March to mid-September, perennial broods. Roosts on buildings in winter. Often colony breeders, in all kinds of cavities and crevices in buildings. Usually easy to recognize by the nesting material hanging out.
House martin: Migratory bird, arriving in the breeding area from mid-April, multi-year broods, leaving in mid-September. Clay nests under eaves. Do not tolerate any disturbance or changes in the immediate vicinity of the nests during the breeding season.
Barn Swallow: Migratory bird, arrival in the breeding area from the end of March, departure from August. Niche breeders, nests usually in freely accessible buildings, up to three annual broods possible.
Jackdaw: A resident bird in cities, otherwise a partial to medium-distance migrant. Arrival at the breeding site from the end of February, departure from July. Cavity nester, nests mostly in buildings, more rarely in tree and rock cavities.
Kestrel: Partial migrant, often breeds on buildings, but also on technical structures such as electricity pylons. Breeding season from early March to early August.