Last updated on October 23rd, 2023 at 09:05 pm
At the end of March, birds are still looking for nesting sites: here are some practical tips for installing one or more nesting boxes in a garden or on a balcony.
There are several ways to attract and help birds in your garden or on your balcony: feed them in winter, provide them with water for drinking and bathing, plant plants providing shelter and/or food, do not use chemicals to treat your garden and/or install a nesting box. Many species need these artificial nesting sites because their natural habitats are being depleted: hedges and dead trees are disappearing, the facades of new buildings are smooth and airtight, old woodpiles and brambles are eliminated and low walls are destroyed. Even if the installation of a nest box does not compensate for this trend, it is a concrete gesture for our winged friends and a source of wonder for adults and children. In this article, we give you several important practical tips to maximize the chances that your nest box will be used and appreciated by the birds.
There are several ways to attract birds to the garden or on your balcony: ging them sum food in winter, providing them water for drinking and bathing, planting bushes, trees and flowers, avoiding the use of chemicals products or installing a birdhouse. Several bird species need these artificial breeding sites because their natural habitats is les and less favorable for them: hedges and dead trees disappear, the facades of new buildings are no welcoming, old piles of wood and brambles are eliminated and old walls are destroyed.
Even if installing a nestbox will not reverse this negative trend, it is a concrete gesture for our feathered friends and a source of wonder for adults and children. In this article, we propose you several tips to maximize the chances that your birdhouse will be used and enjoyed by birds.
Choose a suitable model
The size of the entrance hole allows you to select the hosts you wish to favour (see The different types of birdhouses):
For the blue tit (Cyanistes caeruleus), black tit (Periparus ater) and tit (Poecile palustris), the hole will have a diameter of 25 mm.
For the Chickadee (Parus major), the Sparrow (Passer montanus) and the Black Flycatcher (Ficedula hypoleuca), the diameter will be 28 mm.
It will reach 32 mm for the House Sparrow (Passer domesticus) and the Nuthatch (Sitta europaea), and 45 mm for the European Starling (Sturnus vulgaris).
Woodpeckers like to dig their own cavity: you can plug the hole in the nest box with a piece of balsa wood so that they feel like they have done some digging.
Other species prefer nest boxes with a large rectangular opening at the front: 60 mm for the Gray Flycatcher (Muscicapa striata), 100 mm wide for the House Robin (Erithacus rubecula), the Blackbird (Turdus merula) or the Gray Wagtail (Motacilla alba).
The inside of the nest should not be too smooth so that the young birds can easily climb out: you can create a kind of ladder by gluing small parallel pieces of wood to the back wall (on the inside). You can also roughen the wall.
There are many ready-made nesting boxes for different species on the market, but it is also possible to build them yourself, involving your children. There are several plans available on the web, for example on Nichoirs.net. And don’t forget that there are also nesting boxes for bats!
Securely attach the nesting box to its support
You must attach your nesting box to a solid and stable support, with one or more fasteners that are not likely to rust or deteriorate over time (galvanized wire, sheathed electrical wire…). If you attach it to a living tree, be careful not to injure it: do not use nails, which may also rust (prefer stainless steel). Do not place a piece of wood between the trunk and the wire to prevent the tree from growing.
Check from time to time that the nesting box is still firmly attached to its support.
Choosing good materials
The nesting box must be solid, sturdy, made with boards at least 15 to 18 mm thick. Avoid treated wood (or use non-hazardous products): with time, it will take on a duller color that will help it blend into the environment. However, the softest woods can be treated with Sadolin, a product that is not dangerous for birds: limit its application to the outside of the nesting box, avoiding the perimeter of the hole, and let it dry well before installation. Do not use wood impregnated with copper chromium arsenate.
Good birdhouses are not necessarily made of wood: for example, those from Schwegler are made of “wood concrete,” a mixture of cement and sawdust.
Do not put any fillings in the box (straw, moss…), the birds will bring them. However, for large species such as owls or woodpeckers, a layer of sawdust or shavings can be placed on the bottom.
Choose a sheltered location
The chosen place should be quiet, rather far from a road or a frequented path. It is especially important to install the nesting box in a place as sheltered as possible from bad weather. East, South-East or even North-East orientations are ideal. The nesting box should not be exposed all day to the sun or permanent shade. Place it away from the prevailing winds, for example behind a bush, avoiding that leaves obstruct the entrance of the nest.
Be careful, the inside of the nesting box must remain dry: it is thus necessary to make sure that the boards are well joined. It is advisable to tilt it slightly forward to facilitate the flow of rain. The nesting box should not be in the path of a trickle of water that would form after a rainfall. You can drill a small drainage hole in the floor to facilitate drainage. Avoid damp locations (moss on trunks or rocks is a bad sign).
Some birds, such as robins, require that the nest box be relatively hidden, for example against a wall with ivy.
Beware of predators
It is important to install the nest box in a way that is safe from predators (cats, squirrels…): you can for example place a large mesh screen around the nest box, place thorny branches at the base of the post or trunk, plant a rosebush or fix a “stop-matou” around the trunk.
It should be placed high up, ideally at least two meters from the ground, at least 1.50 meters. Place it preferably against a trunk rather than a branch, and avoid having leaves obstruct the entrance.
Wide-open nest boxes should generally be placed lower (less than 2 meters) than those with a circular entrance.
Here are some recommended heights for several species:
House robin (Erithacus rubecula): 1.5 to 5 meters
Music thrush (Turdus philomelos): 1.5 to 2 meters
Grey wagtail (Motacilla alba): 1.5 to 2 meters
Garden Creeper (Certhia brachydactyla): 1.5 to 5 meters
Blackbird (Turdus merula): 1.5 to 6 meters
Green Woodpecker (Picus viridis): 2 to 6 meters
Spotted woodpecker (Dendrocopos major) : 3 to 5 meters
Black Redstart (Phoenicurus ochruros) : 2 to 6 meters
Nuthatch (Sitta europaea) : 2 to 6 meters
Kestrel (Falco tinnunculus): 8 to 12 meters.
A metal plate placed around the entrance, which can be bought in stores or made by yourself, will prevent the hole from being enlarged by mammals such as squirrels or mustelids (weasels, martens…).
To prevent cats from killing the birds in the nest box by pawing, the bottom of the box should be located at least 13 cm from the hole (for models with a circular entrance).
For shallow nests, such as those for robins, redstarts and flycatchers, you can place a wire mesh around it. It is preferable for these species that the entrance is not too visible: you can, for example, make sure that ivy climbs on the protective screen.
It is important to prevent predators from getting too close, for example by adding a protective branch. Parents should be able to land near the entrance, however, as they usually do not enter directly.
Hornets or wasps may want to build their nests in a nesting box: if there is a real risk, you can line part of the walls with wool to prevent these hymenoptera.
It is preferable to install your nesting box in autumn or at the beginning of the winter: it will then be spotted by the birds before spring. Some species, such as chickadees, can move in very early (as early as the end of winter), while others, such as wrens, can spend the winter there (read How do birds cope with winter nights and how can you help them?) It is in fact possible to install nest boxes all year round, including in April, May or June, although those put up later will be less likely to be occupied before the following season (read Putting up a nest box in spring, is it too late?). Installing nesting boxes in a staggered manner allows you to target the species you wish to favor or not: for example, a nesting box for Redstart installed before the end of April will prevent it from being occupied by sparrows or chickadees.
Some birds, such as the Gray Flycatcher (Muscicapa striata), return late from their migration (late May), others nest several times during the year, and some who have had to abandon a nesting site will be delighted to find one available. Finally, your nest box will surely be spotted by birds visiting your garden and they may occupy it next spring. It can take up to a year to use a nest box, so don’t lose patience! On the other hand, if a nesting box is not occupied two years in a row after its installation, it is because the location is not suitable (frequent disturbances, strong predatory pressure, territory already occupied…).
It is necessary to keep a minimum distance between the nesting boxes
You can enjoy the spectacle of bird nesting without disturbing them by installing a video kit for birds.
Avoid placing two nesting boxes for the same species or for species that are direct competitors for food. The “safety” distance varies according to the species: at least 20 meters for chickadees and 70 meters for the White-fronted Redstart (Phoenicurus phoenicurus) and the Nuthatch (Sitta europaea). But you can install nest boxes for species that are not in direct competition with each other, such as a granivore and an insectivore, closer together.
For birds nesting in colonies (sparrows, starlings, swallows), this question of minimum distance does not arise of course.
Nest boxes should also be installed as far away as possible from feeders and bird baths to avoid disturbance and intrusion.
Keep your visits to a minimum. Use binoculars to watch the parents and young from a distance without disturbing them. You can also install a mini-camera to follow the nesting from a distance. If you find chicks on the ground, pick them up and put them back in the nesting box to keep them safe.
Cleaning the nest box in the fall
The nest box should be easily accessible so that it can be cleaned at the end of the nesting season (read October, a good month for cleaning nest boxes). Prefer models with a removable lid to facilitate cleaning. In autumn, from September onwards, empty the nesting box, brush the inside, clean it with water if necessary, dry it and apply an anti-parasite product that is safe for the birds. You can use thyme oil, for example. Birds use certain plants themselves to keep pests away (see Some birds use their knowledge of botany to build their nests). Then check that the boards are well joined and that the attachment is still solid.
Convince your friends and family
Convince your friends, your acquaintances, your company, your association or your town hall to also install nest boxes (read Favouring the Window Swallow in the city: the example of Gembloux). Natural cavities are indeed more and more rare, and modern buildings offer less and less favorable sites to birds: you can help them!