Nest box - correct hole size for 20 species of birds

Nest box - correct hole size for 20 species of birds

the essentials in brief

  • Correct nest box hole sizes for common bird species: tits 26-28 mm, sparrows 32-34 mm, starlings 45-50 mm.
  • Blackbirds, wren and robins are half-cave breeders and want a nest box (€ 8.76 on Amazon *) with a wide slot as an entrance opening.
  • Nest boxes for each bird species have at least 4 bottom holes with a diameter of 3-4 mm for ventilation and dehumidification.

Build a nest box - hole size table

nest box hole size

Hobby gardeners who are close to nature have an open ear for the great housing shortage in the local bird world and build a hospitable nest box. The type of bird found here and starts a family depends on the diameter of the entry opening. The following table shows which hole size is suitable for which bird:

also read

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  • The right hole size for your insect hotel
  • What can be done against bumblebees in the nesting box?
Bird speciesHole size Ø mm
Blue tit26-28
Tree Sparrow30 × 45 (oval)
Common redstart47
House Sparrow / Sparrow32-34
Crested tit26-28
Stock dove85
Great tit32-34
Common Swift32 × 64 (oval)
Barn owl200 × 150 (oval)
Pygmy Owl45-50
Little owl80
Pied flycatcher32-34
Kestrel160 long slot
brown owl120
Scops Owl65-70

In addition to the entrance opening, please drill 4 holes in the bottom for ventilation and humidification with a diameter of 3-4 mm each.


Blackbird, wren and robin nest in the half-cave box

Not all garden birds want a home with a loophole. Blackbirds, wrens and robins like to breed in niches and crevices. Because the three native bird species do not like to squeeze through a narrow entrance, they are left behind in the classic cave breeder box. Ambitious bird lovers don't have to say that twice and build a half-cave nest box. This simplifies the construction work because there is no need for precise measuring and drilling for the appropriate entrance gate. The picture below shows the simple construction of a half-open nesting box for blackbird, wren or robin:

Example of a half-cave nest box without an entrance hole

Build your own nest box - table for dimensions and hanging height

The right hole size doesn't make a turnkey birdhouse. So that your feathered tenants can set up a cozy nursery behind the entrance hole, species-appropriate dimensions are also important. To protect the small family of birds from cats, martens and other predators, the correct hanging height also plays an important role. The ideal data for our top 20 native bird species is summarized in the following table:

Bird speciesInternal dimensions WxDxH mmSuspension height
Blue tits / titmouse140x140x2501.5-3.5 m
Jackdaw250x250x3506.0-15.0 m
Common redstart140x140x2501.5-3.5 m
Goosander300x300x7702.0-4.0 m
Stock dove250x250x3506.0-15.0 m
nuthatch140x140x2501.5-3.5 m
Common Swift170x280x1107.5-20.0 m
Barn owl1000x500x5003.0-20.0 m
Sparrows / sparrows140x140x2501.5-3.5 m
woodpecker150x150x2803.0-7.0 m
Pygmy Owl220x250x3503.0-10.0 m
Starlings160x160x3203.0-10 m
Little owl160x160x9003.0-10.0 m
Pied flycatcher140x140x2501.5-3.5 m
Kestrel410x230x2506.0-10.0 m
brown owl300x300x4704.0-10.0 m
hoopoe220x250x3503.0-10.0 m
Scops Owl180x180x3803.0-7.0

The following video from NABU-TV explains how you can build a nesting box for starlings with the correct hole size yourself in a practical and understandable way:


Tips & tricks for nest box builders

Important parameters set the course so that life pulsates in the self-made nest box. Supporting pillars are the correct hole size, appropriate dimensions and a safe suspension height, the values ​​of which are indicated in the tables above. The following tips & tricks sum up what also contributes to a premium quality bird house:

Bird-friendly materials

nest box hole size

Use unplaned wooden boards from FSC-certified, sustainable forestry. The timber should be at least 18 mm thick. A rough wooden surface is an advantage so that the chicks can also cling to the side walls inside. Larch, oak and robinia wood promise the best durability. Conifers such as pine, spruce and fir are cheaper and still acceptable. Chipboard or plywood are not weatherproof and therefore not suitable.

Screws are a better choice when building a fine nest box. By doing without nails, you save yourself time-consuming gluing and construct a stable, long-lasting home for the feathered residents.

Chemical wood preservatives are taboo when building a healthy nursery for blackbirds, thrushes, finches and starlings. If you want to protect the bird house from fungal attack and moisture, ideally paint the outer walls with organic linseed oil or a harmless paint with the “Blue Angel” eco-label.

Galvanized sheet steel is a good protection against rain for the birdhouse roof. You can confidently cross bitumen cardboard off the material list as a roof covering. Years of practice have shown that in this case a nest box still becomes damp. Fast drying in the interior is often even hindered by the cardboard.

Safety first

Three important precautions ensure additional safety in the nest box:

  • Roof overhang : the greatest possible overhang of the roof over the entrance hole so that predators cannot reach into it from above
  • Distance from the bottom edge of the hole to the ground : at least 17 cm to protect against greedy marten and cat paws
  • no perch : without a perch, cats, martens and other predators will find no support

If the nest box is not intended for a woodpecker family, you can protect the entrance hole from brazen plunderers in plumage. To do this, mount a galvanized steel safety shield using screws. Thanks to this provision, a pounding beak cannot simply enlarge the opening, throw out the current tenants and annex the aviary. You can buy sturdy safety covers to match the size of the hole as accessories or spare parts from specialist retailers, for example at for an economical 3 euros complete with 4 screws.

Hang the nest box expertly

nest box hole size

A self-made nesting box will be a hit in the bird world if you take the following aspects to heart when hanging it up:

  • Orientation : the entrance hole should point to the east or southeast, under no circumstances to the west facing the weather
  • Tree-friendly fastening : fasten to trees with coated wire and rustproof screws
  • Direction of hanging : Hang up the nest box with a slight transition to the front so that rain can drain off easily
  • Time : the best time is in autumn, because nesting aids are ideal winter quarters for birds, insects and small mammals

A minimum distance of 10 meters is recommended for nest boxes of the same type. This ensures that the breeding bird species can find enough food for itself and the insatiable offspring. An exception applies to colony breeders, such as sparrows and starlings, who like to look after the chicks in close proximity. Nesting aids with entrance holes of different sizes should keep a distance of at least 3 meters.

Special case of half-cave box

Because a wide gap serves as access to the half-cave nest box instead of a narrow entrance opening, trees are not suitable as a hanging location. Nesting boxes for blackbirds, wren and robins are excellently placed on facades, on balconies, on sheds or garden sheds. (7.70 € at Amazon *) Here cats and martens find little starting point to attack the young bird family.

frequently asked Questions

How big should the entrance hole in the nest box for a budgie be?

nest box hole size

A hole size of 35-40 mm is suitable for the nest box for a normal-sized pair of budgie parents. If the two parents-to-be are well positioned in the food, the diameter of the entrance hole can be increased to 50-55 mm.

As a hobby gardener, I have a green thumb, but two left hands when doing DIY handicrafts. Where can I buy a ready-made nesting box for tits with the correct hole size?

The NABU shop is a good source of shopping for decorative tit nest boxes. You can purchase a species-appropriate nesting aid made of FSC wood for blue tits and conspecifics for as little as EUR 12.99. The product selection based on the size of the entrance hole is practical. If you only want to grant access to the somewhat larger great tit, simply choose a nest box with a hole size of 32 mm, which is even cheaper as a birch nesting aid at 7.99 euros.

How can you hang nest boxes as gently as possible?

For nesting boxes for small species of birds, such as titmice or sparrows, use a sheathed wire that does not cut into the tree bark when hanging. If it is a large nest box for starlings, we recommend a disused garden hose as an additional cover. Cut a binding wire and old water hose to the correct length, with the binding wire sticking out a little at both ends. A screw eye on each side wall of the nest box serves as a holder for the wire, the ends of which you twist firmly.

Can a nest box hang freely or should I mount it securely?

Both variants are possible. However, it should be remembered that a nesting box with young birds should not be a swing. The hard-working bird parents will appreciate a less mobile kindergarten, so that every feeding of the hungry beaks does not become a balancing act. There is also the risk that unsafe chicks will fall out of a dangling nest box more quickly.


Primarily hobby gardeners who create and design their garden close to nature can look forward to a fully utilized nesting box. Where local flowering bushes are splendidly in the limelight and pesticides are frowned upon, the table is richly set with nutritious berries, insects, maggots and larvae for growling bird bellies. If bird cherry (Prunus avium), hawthorn (Crataegus) or black elderberry (Sambucus nigra) flourish in the garden, every bird feeder is in great demand as the perfect refuge for starting a family.