Entrance Hole in Nest Box with Camera: 3.2 cm or 4.5 cm – which size suits which bird species?

The nest box with camera is installed, breeding season is approaching – but which entrance hole size is ideal: 3.2 cm or 4.5 cm? This is precisely where it's decided which bird species will even accept your box as a home. In this guide, you'll receive clear guidelines, concrete examples of species for Germany and Switzerland, and practical decision-making help so that your nest box doesn't remain empty but is optimally utilized.

Entrance Hole Basics in a Nest Box with Camera

In a nest box with a camera, the entrance hole serves a dual purpose: it must allow the target species to enter while keeping larger birds and predators away as much as possible. The two common diameters, 3.2 cm and 4.5 cm, cover different size classes in Central Europe. Not only the head circumference of the birds is decisive, but also their behavior, territorial claims, and need for security during breeding.

For Germany and Switzerland, it has been established that smaller tit and sparrow species prefer hole sizes between 28 and 32 mm, while starlings and similar species need openings of about 45 mm or more. A variable nest box, where you can change the entrance hole plate, is therefore ideal for adapting your garden to the bird species actually present and making optimal use of the camera.

If you also want to document the feeding and social behavior of garden birds, a discreet bird feeder with an integrated camera can be a useful addition. This way, you can capture both the breeding routine in the nest box and the activity at the feeding station throughout the year.

Which Bird Species Suit 3.2 cm and 4.5 cm

The 3.2 cm opening is suitable in Germany and Switzerland primarily for small cavity nesters: great tits, blue tits, coal tits, crested tits, and also tree sparrows or house sparrows can easily use this size. The 4.5 cm opening, on the other hand, is interesting for significantly larger species like starlings, nuthatches, or occasionally great spotted woodpeckers, but requires a very sheltered location, as more disturbances and competition are to be expected.

Important: Each species not only has anatomical limits but also species-specific preferences. Some tits will also use a slightly larger hole if the box is particularly attractive or there is a shortage of nesting sites. Nevertheless, it makes sense to follow proven guidelines to specifically attract certain bird groups and not choose an overly large opening "on speculation."

For a realistic expectation of your camera recordings, the breeding cycle of the species is also crucial: starlings, for example, feed their young very intensively, which leads to exciting but also very dynamic images. Tits often breed early in the year and also use the box as a roosting place outside of breeding, allowing you to document more days of usage behavior.

If you answer these questions honestly, a clear picture usually emerges as to whether your nest box with a camera is more likely to be accepted by tits/sparrows or by starlings and nuthatches. Based on this, you can confidently determine the entrance hole size.

Decision Aid: 3.2 cm or 4.5 cm?

In most gardens in Germany and Switzerland, the 3.2 cm entrance hole size is the more practical and safer choice: it attracts common species like tits and sparrows, offers good protection against larger competitors, and typically leads to a high probability of colonization. The 4.5 cm opening is worthwhile primarily if you specifically want to observe starlings or nuthatches and can prove their presence in the immediate vicinity.

To make your decision easier, a sober look at your goals is worthwhile: Is the main goal to have a brood at all and for your family to get exciting insights? Then the smaller opening has a statistical advantage. If, on the other hand, you specifically want to document larger species with striking behavior, you can consciously test the 4.5 cm entrance hole – ideally after a season in which you have gained experience with the smaller opening.

When the 3.2 cm entrance hole makes sense

The 3.2 cm entrance hole is particularly suitable if your garden is rather small or semi-open (terraced houses, city outskirts, balconies) and if you already observe tits and sparrows at the bird feeder. Even with a high density of cats or magpies, the smaller opening has an advantage because it makes access for larger animals more difficult. For families with children who want to reliably experience a brood at the nest box with a camera every year, this is usually the best starting option.

When the 4.5 cm entrance hole is the better option

The 4.5 cm opening becomes interesting if you regularly see starlings in your garden or on adjacent meadows and your property is rather open in structure. In traditional orchards, large gardens with old trees, or at the edges of forests, starlings and nuthatches can be among the dominant cavity nesters. Here, it is worthwhile to deliberately choose the larger hole to increase the chance of spectacular camera footage – for example, when feeding starling fledglings.

Which choice suits whom

For beginners, city dwellers, and families who "just" want to collect successful nature observations, the 3.2 cm entrance hole size is clearly recommended. Experienced garden owners with large, structurally rich properties can deliberately experiment with 4.5 cm – ideally with a second box or after a season of tit experience. This way, you avoid disappointment and strategically use the flexibility of your nest box with a camera.

Common Mistakes in Choosing the Hole Size

Many problems with empty nest boxes can be attributed to three causes: wrong entrance hole size, unfavorable location, or too late installation. The good news: all three points can be avoided with some planning. Especially with a flexible nest box with a camera, a conscious approach is worthwhile instead of randomly selecting the entrance hole plate.

Another common mistake is to only focus on desired species: anyone who absolutely wants to observe owls or woodpeckers with a camera quickly opts for large openings out of enthusiasm, without checking whether such species even occur in the settlement area. It is more realistic to start with tits and sparrows and only change the entrance hole size when the range of species in the vicinity or your spatial possibilities have expanded accordingly.

Typical misunderstandings about hole size

It is often assumed that birds will "somehow" build their nest even with the wrong size. In practice, many species are surprisingly selective: if the hole is too large, the box is ignored for security reasons. If it is significantly too small, use fails due to purely physical limitations. Therefore, it is worthwhile to carefully align with the standard sizes proven in Germany and Switzerland – 3.2 cm for small cavity nesters, 4.5 cm for larger species like the starling.

How to Change the Entrance Hole Plate Step by Step

Changing between 3.2 cm and 4.5 cm entrance holes is straightforward in practice but should always be done outside of the breeding and rearing season. Ideally, plan the change in late autumn or very early spring, before the first birds regularly show interest in the nest box. This avoids stress for the animals and at the same time provides unadulterated observations with your camera.

After the change, a quick camera test is worthwhile: check the image section, brightness, and focus so that you don't have to readjust inside during breeding. This keeps the nest box completely undisturbed during the sensitive phase, and you get calm, meaningful recordings of the breeding process.

Conclusion: How to Make the Right Choice

Frequently Asked Questions about the Entrance Hole in a Nest Box with Camera