Nests & Nesting MaterialSome finches don't seem to care about where they lay their eggs or what nesting materials they have to work with. Zebra finches especially are notorious for attempting to lay their eggs in a seed dish, or even in a potted plant without the use of any additional nesting materials. Some finches will lay their eggs directly on the floor of their enclosure, while others will lay an egg while standing on a perch (causing the egg to drop to the floor and break). None of these situations results in a successful nest. If you wish to breed your birds, you will need to take steps to avoid these problems. First, if you notice your birds attempting to use a seed dish as a nest, switch from seed cups to tube feeders. Next, if you notice your birds attempting to use other undesirable locations within their enclosure to lay eggs, this is probably because they do not have access to a more suitable nesting site or desirable nesting materials. Both of these problems are easy to remedy, as described below.
Choosing the Right NestBreeding finches in need of a nest generally fall into two different categories. Those that accept artificial nesting sites, and those which prefer to build their own nests from scratch. In general, the more "domesticated," the species, the more likely they are to accept an artificial nesting site. Many people chose to provide their birds with bamboo nests, such as those pictured to the left. Some finches will readily accept a domed bamboo nest or a bamboo nesting cup. Other finches, however, may prefer a half-open nest box or a nest box with a U-shaped entry hole. Unfortunately, most of the nests available at pet shops are made of bamboo, twigs, or another form of wood. The problem with this is that wood is impossible to disinfect, so nests which have been fouled with feces cannot be reused,5 and instead should be discarded after each clutch (this will help to maintain good hygiene and reduce the potential spread of disease). Another problem with wooden nests is that some types of wood are toxic to finches. Cedar, redwood, and pressure-treated woods all contain chemicals which have caused cancer in rodents and are considered harmful to birds.5,6
The best solution for an artificial nesting site, therefore, is a plastic nest box. Although they are slightly more susceptible to temperature variations (only important if the birds are being bred outdoors in intemperate weather), plastic nest boxes are easy to clean and disinfect, making them reusable. They also come with a flip-up top, which makes nest checks much easier to perform. They can be hooked to the outside or the inside of the cage, and they come with a removable "entrance perch" which can be used to aid the birds in accessing the nest if other nearby perching is unavailable. They meet the recommended size requirement for a finch nest box (~5.5" in length)13 and may be found for sale online for about $5 (US) per nest. Please note that canary nesting cups made of plastic (as opposed to bamboo) may also be found for sale, and are perfectly acceptable for those birds which prefer to build their nest in a cup instead of a box.
Providing several different styles of nests to your finches will allow them to chose the type of nest that they prefer. For instance, pytilias, twinspots, and most waxbills seem to prefer a nest box with a half-open entrance, whereas parrot finches may prefer a box with a U-shaped entrance.13 Of course, there are still those finches will refuse artificial nesting sites (such as purple grenadiers and violet eared waxbills),13 and those finches which might accept an artificial site, but would still prefer to build their own nest from scratch when given the opportunity.
In order to give those birds which refuse artificial nesting the opportunity to build their own nest, you will need to include live, nontoxic plants in their enclosure. Provide dense shrubs such as boston ferns (hanging or on the ground) or plants with abundant branches such as gardenias. These birds will also need plenty of suitable nesting materials, as described below.
Choosing the Right Location for the NestFinches prefer that their nest boxes be placed up high, so usually nests placed near the upper corners of the enclosure are best. Ideally, these nests should be eye level to you13 so that you can perform nest checks more easily, if necessary. Placing nests on the outside front of the cage (if it is safe and possible to do so) gives you the easiest access to them; nests placed inside the cage are harder to reach and take up the birds' flight space.8
Note: If the birds are being bred outdoors, make sure to place the nests in a covered area (such as under the aviary roof) to shelter them from wind and rain.8,10
If space allows, provide at least two nesting options per pair: place different styles of nests in different locations and allow the pair to choose.11,12,13 Providing more nests than there are pairs of birds in an enclosure is especially important if you are attempting to colony breed. In this case, make sure that all of the nests you provide are at comparable heights and locations to reduce bickering among pairs.12
Secluding the nest(s) by placing items such as nontoxic live or silk plants around them provides a sense of security to the parents by providing a visual barrier. Screening the nests in this way also helps to reduce aggression as well as decrease the likelihood of nest abandonment.8 Make sure that each nest has a perch near its entrance (within a half inch) so that the finches may investigate and gain access to the nest more easily. Also, providing lighting near the nest entrance may encourage pairs to enter.
A small number of finches (such as the quail finch) will nest directly on the enclosure's floor. In this case, providing branches of conifer trees in a quiet corner of the cage or aviary may encourage these birds to nest.8
Selecting the Right Nesting MaterialProvide your birds with nesting materials that are natural and nontoxic. Avoid small, synthetic fibers such as yarn and stringy material such as hair. These fibers can become entangled around the bird's feet, toes, and other body parts, causing damage, loss of limb, and even death.7 Also avoid hay, soil, peat moss, eucalyptus leaves, and corn cob (which may lead to fungal growth).2,5
Burlap cut into 3" strips, shreds of newspaper, coconut fiber, and shreds of facial tissue are good nesting material options.5,7 Additionally, certain species prefer certain types of nesting material: parrot finches, for instance, prefer to use broad-leafed grasses and reeds13 whereas painted finches like to include stones and small twigs in their nests.8 Some finches even like to line their nests with white feathers.8 The key is to provide a wide variety of nesting materials and then let the birds decide what they want to use. Both the cock and the hen will help to build the nest, which often resembles a sphere when it is complete. Some species (such as the black cheeked waxbill) will expand the entry of their nest into a passageway.13
To start the birds off, place a little nesting material inside of their nest and place the rest around the enclosure for them to gather (e.g. on the floor of the cage, but not under any perches so that the material does not become soiled). Some pairs will not begin laying eggs until their nest is built up to their satisfaction, so keep providing nesting materials until the nest is complete. Weaver finches are a good example of a species which requires large amounts of nesting material: because the weaver cock is polygamous, he will build several ornately woven nests (one per hen).8 A word of warning, however: some birds, usually zebra finches, will overbuild their nest, resulting in an entrance which is too shallow to keep the eggs inside. As the parents exit the nest, they may accidentally knock the eggs out, often causing them to break. Other pairs may try to make use of extra nesting material by building a nest on top of an existing clutch of eggs. If you have a pair of birds which has problems keeping their eggs inside of their nest, or a pair which buries their eggs, you will need to vastly limit the amount of nesting material you make available to these overzealous nest builders. For these birds, once the nesting material is built to a level of about a half inch below the entrance to the nest, remove any excess nesting material.
Tip: placing a small rattan basket within a nesting box can help keep a clutch of eggs together.13Nest material should be kept dry and replaced after each clutch to prevent overgrowth of potentially pathogenic organisms which could lead to illness (e.g. aspergillosis, mucormycosis, sporotricosis in nestlings, and viral diseases).2