Which feathered friend you grant access to the self-made nesting box depends on the diameter of the entrance opening. Only the bird species whose body fits through the entrance is allowed access. Here, aviary builders can use a table to find out the correct nest box hole size for 20 bird species. Practical tips & tricks reveal how you can build a fully booked home for tits, starlings and other birdies yourself.

Each bird has its own preferences regarding nest box hole size

Table of Contents

Show all
  1. the essentials in brief
  2. Nest box hole size table
  3. Nest box dimensions and hanging height
  4. Tips and tricks
  5. frequently asked Questions

    6. the essentials in brief

    • Proper nest box hole sizes for common bird species: Tits 26-28mm, Sparrows 32-34mm, Starlings 45-50mm.
    • Blackbirds, wrens and robins are semi-cave breeders and want a nesting box (€49.85) with a wide slit as an entry opening.
    • Nest boxes for each bird species are given at least 4 holes in the bottom with a diameter of 3-4 mm for ventilation and dehumidification.

    Building a nest box - hole size chart

    Blue tits need a hole size of 26-28cm

    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 nesting box. Which bird species arrives here and founds a family depends on the diameter of the entrance opening. The table below shows which hole size is suitable for which bird:

    bird species Hole size Ø mm
    blue tit 26-28
    Jackdaw 85
    tree sparrow 30×45 (oval)
    Redstart 47
    goosander 150
    House Sparrow/Sparrow 32-34
    crested tit 26-28
    stock dove 85
    nuthatch 32-47
    great tit 32-34
    swift 32×64 (oval)
    barn owl 200×150 (oval)
    woodpecker 45-50
    pygmy owl 45-50
    little owl 80
    pied flycatcher 32-34
    kestrel 160 long slot
    brown owl 120
    hoopoe 70
    scops owl 65-70

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

    digression

    Blackbirds, wrens and robins nest in the semi-cave box

    By no means all garden birds want a home with a loophole. Blackbirds, wrens and robins prefer to breed in niches and crevices. Because the three native bird species don't like to squeeze their way through a narrow entrance, they lose out in the classic cave breeder box. Ambitious bird lovers don't need to be told twice and build a semi-cave nest box. This simplifies the construction work because there is no need for precise measuring and drilling for the right entrance gate. The picture below shows the simple construction of a half-open nest box for blackbirds, wrens or robins:

    Build a nesting box yourself - 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 comfortable nursery behind the entrance hole, species-appropriate dimensions are also important. The correct suspension height also plays an important role in protecting the small bird family from cats, martens and other predators. The following table summarizes the ideal data for our top 20 native bird species:

    bird species Internal dimensions WxDxH mm suspension height
    Blue Tits/Tits 140x140x250 1.5-3.5m
    Jackdaw 250x250x350 6.0-15.0m
    Redstart 140x140x250 1.5-3.5m
    goosander 300x300x770 2.0-4.0m
    stock dove 250x250x350 6.0-15.0m
    nuthatch 140x140x250 1.5-3.5m
    swift 170x280x110 7.5-20.0m
    barn owl 1000x500x500 3.0-20.0m
    Sparrows/Sparrows 140x140x250 1.5-3.5m
    woodpecker 150x150x280 3.0-7.0m
    pygmy owl 220x250x350 3.0-10.0m
    starlings 160x160x320 3.0-10m
    little owl 160x160x900 3.0-10.0m
    pied flycatcher 140x140x250 1.5-3.5m
    kestrel 410x230x250 6.0-10.0m
    brown owl 300x300x470 4.0-10.0m
    hoopoe 220x250x350 3.0-10.0m
    scops owl 180x180x380 3,0-7,0

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

    youtube

    Tips & tricks for nest box builders

    In order for life to pulsate in the self-built nesting box, important parameters set the course. The supporting pillars are the correct hole size, species-appropriate dimensions and a safe hanging height, the values of which are shown in the tables above. The following tips & tricks sum up what else contributes to a bird house in premium quality:

    Bird-friendly materials

    When building nest boxes, only natural, untreated materials should be used

    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. Softwoods such as pine, spruce and fir are less expensive and still acceptable. Chipboard or plywood are not weather-resistant and therefore not suitable.

    Screws are a better choice when building a superb nest box. By eliminating nails, you save yourself time-consuming gluing and construct a strong, 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 aviary from fungal infestation and moisture, ideally paint the outer walls with organic linseed oil or a harmless paint with the "Blue Angel" environmental label.

    Galvanized sheet steel is good rain protection for the birdhouse roof. You can confidently remove bitumen felt as a roof covering from the list of materials. Years of practice have shown that a nesting box will still get wet in this case. The cardboard often even hinders fast drying in the interior.

    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 in from above
    • Distance from the lower edge of the hole to the floor: at least 17 cm distance as protection against greedy marten and cat paws
    • no perch: Without a perch, cats, martens and other predators cannot find a footing

    If the nest box is not intended for a family of woodpeckers, you can protect the entrance hole from bold plunderers in plumage. To do this, mount a galvanized steel safety shield using screws. Thanks to this provision, a pounding beak cannot simply widen the opening, throwing out the current tenants and annexing the aviary. You can buy robust safety covers matching the size of the hole as an accessory or spare part in specialist shops, for example at nistkasten-online.de for an economical 3 euros, complete with 4 screws.

    Properly hang up the nest box

    A nest box should be high enough and face east or south-east if possible

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

    • alignment: the entrance hole should point to the east or south-east, not to the west weather side
    • Tree-friendly attachment: attach to trees with sheathed wire and stainless screws
    • hanging direction: Hang up the nest box with a slight transition to the front so that rain can run 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 nesting boxes of the same design. This ensures that the breeding bird species finds enough food for itself and its insatiable offspring. An exception applies to colony breeders, such as sparrows and starlings, who like to care for the chicks in close proximity. Nesting aids with entrance holes of different sizes should be at least 3 meters apart.

    Special case semi-cave box

    Because a wide gap serves as access to the semi-cave nest box instead of a narrow entry opening, trees are not suitable as a hanging location. Nesting boxes for blackbirds, wrens and robins are excellently placed on facades, on the balcony, on the shed or garden shed. (24.90€) Cats and martens find little starting point here to attack the young bird family.

    frequently asked Questions

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

    Nest boxes for budgies should have a hole size of about 4cm

    A hole size of 35-40 mm is suitable for the nesting box for a normal-sized budgie parent pair. If the two expectant parents are well fed, the diameter of the entry hole can be increased to 50-55 mm.

    As a hobby gardener, I have a green thumb, but two left hands when it comes to DIY handicrafts. Where can I buy a ready-made tit nest box with the right hole size?

    A good source of shopping for decorative tit nest boxes is the NABU shop. You can purchase a species-appropriate nesting aid made of FSC wood for blue tits and conspecifics from a thrifty EUR 12.99. Product selection based on entry hole size is practical. If you only want to grant access authorization to the slightly larger great tit, simply select a nesting box with a hole size of 32 mm, which is even cheaper than the birch nesting aid at 7.99 euros.

    How can you hang up nesting boxes in a way that is as tree-friendly as possible?

    For nesting boxes for small birds such as tits or sparrows, use coated wire that will not cut into tree bark when hanging. If it is a large nesting box for starlings, we recommend using a used garden hose as an additional cover. Cut a piece of binding wire and old water hose to the right length, leaving the binding wire sticking out a little at both ends. A screw eyelet on each side wall of the nesting box serves as a holder for the wire, whose ends you twist tightly.

    Can a nesting box hang freely or should I mount it firmly?

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

    tips

    Primarily hobby gardeners who create and design their garden in a natural way can look forward to a fully utilized nesting box. Where native flowering bushes are magnificently staged and pesticides are frowned upon, the table is richly set with nutritious berries, insects, maggots and larvae for growling little birds. If bird cherry (Prunus avium), hawthorn (Crataegus) or black elder (Sambucus nigra) thrive in the garden, every bird house is in great demand as the perfect refuge for starting a family.

Category:

Animals in the garden