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I intentionally avoid taking nest boxes out until May at the earliest because although we have recently had the warmest April on record here in the UK this is not always the case, there is normally a risk of frost until late May. This is the same reason why it is not recommended to plant your summer plants until late May or early June, the possible risk of frost can cause serious damage.
Your birds’ eggs will likely be fine, as your birds will incubate them themselves, but young chicks in a cold, icy environment is a recipe for disaster.
The size and type of nest box required depends solely on the species of bird you intend to occupy:
Cockatiels will require an upright box with a removable or hinged lid or flap for inspection and cleaning. The nest box should be approximately 12 inches (30 cm) high, 8-9 inches (20-22.5 cm) wide, 8-9 inches (20-22.5 cm) deep, with a round entrance placed to a height of about 2-2½ inches. (5-6.25 cm) in diameter; remember to have a hanger of some sort mounted just below the entry hole. It is advisable to place aviary mesh on the inside of the nest box below the entrance hole, this will help as a ladder rather than the parent bird jumping on the eggs or chicks; but they don’t have such a thing in nature, so it’s not absolutely necessary.
Budgies (budgies, lovebirds) will need a box about 9 inches (22.5 cm) long, 6 inches (15 cm) wide, 6 inches (15 cm) deep with an entrance hole about 2 inches ( 5 cm) in diameter in the upper front corner. A vertical nest box of similar dimensions also works well, but the horizontal type seems to be the most popular. Again, you’ll need a removable lid or door for inspection and cleaning purposes, a perch below the entrance hole, and if using a vertical nest box, wire mesh on the inside below the entrance hole will help for the same reason as the cockatoo box above, but again not essential.
Small finches such as the zebra and Bengals (society) will need a nest box about 5 inches (12.5 cm) in all dimensions with the front slightly smaller in height by about 1-1½ inches (2.5- 3.75 cm) to leave an entrance. opening at the top front, you can have a hanger under the entrance if you want, but it’s not necessary. Finches also often carry a small half-open wicker basket.
Before you take out your nest boxes, you should inspect each one carefully for signs of wear or rot and, if necessary, repair or replace them. Also make sure your nest boxes are hygienically clean, so wipe them down if necessary with a mild disinfectant solution, then rinse them well and allow them to dry completely before use.
Place your nest boxes as high as possible, after all birds usually nest in trees, they like to nest high up. Be sure to set all your nest boxes at the same height, otherwise your birds will fight over the highest location. If you have a mixed aviary, make sure you don’t mix different types of nest boxes in the same place. By this I mean divide your aviary into areas, without the need for barriers, an area for cockatiel boxes, a separate area for parakeet boxes, and a separate area for finch boxes or baskets. If you have nest boxes for different species too close together, this can lead to territorial disputes between different species and can lead to destruction of eggs or attack by chicks.
Unless you’re breeding for the show bank, which requires a totally different approach, it’s best to let your birds choose their own mates and nests.
While breeding and raising young you need to make sure you provide your birds with a constant source of food and fresh water, after all they will need all the energy they can get. Also try not to let your birds raise more than 2 broods per year, 3 max, as once they are done they will need to build up their energy and fat stores to get them through the winter, so be sure to remove nest boxes in the autumn (autumn) when they have done it.
Good luck!