Budgies, or common parakeets, are small, colorful members of the parrot family, and finches are a large family of small birds that include many different species. Common pet finches include the zebra finch, the American goldfinch, the canary and the Gouldian finch.
When mixing birds, it is important to not mix two different bird species with differently-sized beaks. If one species has a larger beak and it attacks the other, the smaller-beaked bird could be injured or killed. Finches and budgies are similar in physical size and in beak size.
One of the most important things to consider when deciding to keep two different species of any animal in the same cage is whether they come from a similar habitat in the wild. For example, it would be difficult to keep a rainforest bird and a desert bird together, because they need different levels of humidity, food and temperatures. Budgies are native to the Australian savanna, and are naturally found in the wild along with zebra finches, so the two species can be kept together.
Budgies and finches can be kept in the same cage as long as they have plenty of activities to keep themselves entertained and busy so they don't pick at each other with their beats. Both birds have the same housing requirements of at least an 18-by-18-inch cage with 1/2 inch spacing between the bars. With birds, no cage is too large, but ensure that the cage is at least big enough to house the budgies and finches comfortably.
Budgies and finches can be kept in the same cage, as long a close eye is kept on them. If there are signs of fighting or territorial behavior, or if the birds become injured, they should be separated immediately. If the birds appear to be injured or missing feathers, then one bird may be bullying the other birds.