The first nesting aids were developed towards the end of the 19th century. At the time, however, environmental protection and bird conservation were marginal issues at best. Rather, nesting aids were developed purely out of economic interest: a growing number of birds were to help decimate the pests that were causing great damage in commercial forests. Over time, more and more different nesting aids were developed and slowly these also found their way into private gardens. But why do we need “different” nesting aids at all?
The answer is quite simple: because the different bird species have very clear ideas about what their nesting place should look like. A distinction can be made between 3 groups of birds:
- cavity nesters
> they prefer to build their nests in protected (tree) cavities with a round entrance hole
- niche breeders
> these birds prefer niches in rocks, buildings, embankments, etc.
- free breeders
> their nests are relatively unprotected on branches or even directly on the ground
In addition to details about these 3 groups, this blog article also tells you what material nest boxes should be made of and what role they play in winter.
Cavity-nesting birds
…different birds are targeted depending on the type of entrance hole:
In the wild, cavity-nesting birds such as tits, redstarts and nuthatches prefer to build their nests in tree cavities, e.g. in abandoned woodpecker holes. Here they are well protected from wind, weather and nest robbers. They therefore prefer nesting boxes that are modeled on these cavities – so-called “closed nesting boxes“. These usually only have a single round entrance hole, the size of which determines which bird will be interested in a particular nesting box.
> My TIP: “A perch in front of the entrance hole, as you might expect, is not desirable. Birds don’t need it and it would only serve as a handle for nest robbers to hold on to.”
A kind of standard size for the hole diameter is 32 millimetres, which will certainly appeal to great tits and sparrows. If the hole is slightly smaller, small tits are (also) attracted, while larger holes are aimed more at larger birds. As the entrance hole gets larger, the base area and height of the box should also increase accordingly.
A rough distinction can therefore be made between the following closed nesting boxes:
Nest boxes for small tits
- Interesting for: Blue Tit, Fir Tit, Marsh Tit
- Entry hole: Diameter approx. 28 mm, position approx. 12 cm above the ground
- Dimensions: Base area approx. 12 x 12 cm, height inside approx. 15 cm
Nesting boxes for great tits and similar birds
- Interesting for: Great tit and crested tit, redstart, house sparrow and tree sparrow, pied flycatcher, nuthatch
- Entry hole: Diameter approx. 32 mm, position approx. 15 cm above the ground
- Dimensions: Base area approx. 14 x 14 cm, height inside approx. 20 cm
Starling boxes
- Interesting for: Starling, Wryneck
- Entry hole: Diameter approx. 45 mm, position approx. 20 cm above the ground
- Dimensions: Base area 15 x 15 cm, height inside approx. 30 cm
> My TIP: “Treecreepers such as nuthatches are happy to have a special nesting box: one with an entrance at the back through which they can enter the box directly from the trunk. For example, a hole or slit can be provided at the top edge of the back wall.”
Niche breeders (e.g. black redstart, wren, robin, white wagtail or gray flycatcher)
…prefer half-open niches and crevices:
In the vicinity of humans, niche nesting birds find suitable nesting sites, especially in older, angled buildings (e.g. bay windows, niches, open beams). Sufficient space and good roofing are particularly important here so that the nest does not get wet later.
The so-called “half-cave nesting boxes” are modeled on these niches and crevices. The natural niche opening, which is more translucent than the entrance hole of cave nesting birds, is imitated by a wider slit. This slit should not be very high so that a certain degree of protection against predators is maintained.
A distinction is made between half cavities, where the front is half closed (wagtails prefer this variant), and three-quarter cavities, which are three-quarters closed.
Free-breeding birds (e.g. blackbird, chaffinch, warbler, red-backed shrike, song thrush, wren)
…build their nests in the open, i.e. relatively unprotected:
Free-breeding birds need dense hedges and bushes to build their nests, which ideally consist of native, thorny wild shrubs. Hawthorn, blackthorn, buckthorn, juniper, dog rose and barberry are particularly popular here. However, classic hedges such as hornbeam, privet or cornelian cherry also make attractive nesting sites.
Materials
Wood, wood-concrete and pumice concrete are particularly suitable materials for nest boxes. I would definitely advise against plastic nest boxes, as these heat up very much in the sun and the young birds may not be able to climb up to the entrance hole on the smooth walls. Both can quickly lead to death.
Nest boxes in winter
Nest boxes also fulfill an important function in winter: they serve as a warm roost for birds, but also for squirrels and butterflies. Birds have a higher body temperature than mammals, namely 39 to 42°C. This temperature must also be maintained in winter – and that takes a lot of energy. Without suitable winter quarters, birds can quickly freeze to death in particularly adverse weather conditions.