Common species of caged birds kept as companion animals in domestic settings include small parrots such as the ever-popular budgerigar (Melopsittacus undulatus) and cockatiel (Nymphicus hollandicus). Passerines such as the domestic canary (Serinus canaria domestica) and Australian zebra finch (Taeniopygia castanotis) are also popular household companions.
Although the husbandry requirements of these species may seem relatively straightforward, they have all evolved for specific niches out in the wild. Therefore, the facets of these niches need to be replicated in captivity to keep the birds healthy. For example, many species of Australian grass finch (such as the zebra finch or the multi-coloured Gouldian finch, Chloebia gouldiae) are nomadic and wide-travelling in their behaviours. This means they can suffer from a lack of exercise if kept in small cages that do not allow flight and different foraging opportunities. Similarly, the ubiquitous budgerigar, the most common and popular companion bird species, is highly social, moving in huge flocks over long distances in search of food and suitable nesting sites.
Health and husbandry considerations
Many of the behavioural and physical health problems seen in caged birds result from a mismatch between their biology, their behavioural needs and how they are being housed as a companion animal (Law et al., 2018). So, when examining an avian patient, veterinary surgeons should ask the owner about housing (style, size and space), social companionship from other birds (same or different species) and the type and quantity of diet provided, as these are often the root cause of poor health.
Many of the behavioural and physical health problems seen in caged birds result from a mismatch between their biology, their behavioural needs and how they are being housed
Figure 1 illustrates the features of caged birds that can be used to determine overall good health and provides a guide for when an owner should seek veterinary attention if their bird is behaving abnormally or not maintaining optimum plumage and body condition.
Socialisation
Birds need to have the opportunity to exercise and socialise. Poor feather condition and bald patches can result from over-preening, which can be caused by stress or boredom and bullying due to inappropriate cage or aviary mates. Birds in mixed aviaries should all be able to access food and water (owners should provide multiple feeding and watering stations) to prevent malnutrition or dehydration due to resource guarding against other birds in the group. Educating owners about species that socialise well together and which pairings to avoid (for example, budgies can be too excitable and “pushy” to be housed in smaller cages with canaries) is key to ensuring good health and well-being for the duration of a bird’s life.
Poor feather condition and bald patches can result from over-preening, which can be caused by stress or boredom and bullying due to inappropriate cage or aviary mates
Nutrition
Treats and complementary foods
A great example of how veterinary practices can educate owners in best practice care (especially for clients new to caged birdkeeping) is how to ration treats around normal daily diet. Millet spray, the seeded heads of Setaria italica, is a common complementary food readily available in pet stores. Although millet spray can be an excellent treat and form of enrichment, there are some drawbacks, especially if hung up whole so the birds must balance on them to eat the seeds. Furthermore, too much of one type of seed can lead to nutritional imbalance (David, 2011). Millet seed is turned into fat easily; therefore, over-provisioning with millet can lead to obesity, especially in cage-housed birds with limited flight opportunities.
Millet can be a fantastic training aid to get birds used to human contact (Figure 2), and this can help owners gain the confidence of their birds, which allows for easier and stress-free health checks. However, unregulated feeding can result in hepatic lipidosis and lipoma (especially on the bird’s chest/crop area), to which budgies seem to be especially prone. Owners should be encouraged to feed millet sparingly alongside a good-quality, nutritionally balanced seed and pellet diet. They should also provide housing that is stimulating and enables exercise (Figure 3).
Seed-based diets
It is always important to buy a quality seed mix that is well packaged, clean and dry. It may be hard to work out how old seed is when purchased, but as seed loses its nutritional content (eg vitamins and minerals) the longer it sits on the shelf, it is crucial to consider this when buying. Providing a mixture of different seeds that are palatable and using some bespoke pelleted feed and a good-quality dietary supplement can ensure a balanced and nutritionally complete diet.
Seed-eating birds have evolved to de-husk and shell seeds and this behaviour can keep the birds occupied and allow for natural foraging opportunities. Research has shown that captive budgies fed on a mixed pelleted diet and on different seed mixes from a range of grasses and cereals showed no significant difference in health status or immune response (Eggleston et al., 2019), suggesting that the variety of food items provided is important in keeping a budgie physically healthy.
Owners should be reminded to provide a small pot of grit for birds on a seed diet as this is ingested to help grind up seeds and other hard food in the bird’s ventriculus
Owners should be reminded to provide a small pot of grit for birds on a seed diet as this is ingested to help grind up seeds and other hard food in the bird’s ventriculus (often called the gizzard).
“Sour crop”
Owners of budgies should also look out for “sour crop” (Worell, 2012) – an infection in the crop that stops it emptying normally – and keep a regular check on their birds for signs of toxicosis (LaBonde, 1995). The latter is particularly important in species with stronger bills, like cockatiels, and often occurs in the home when birds can fly freely around a room. Chewing and ingesting heavy metals, for example from paint work or curtain weights, can be fatal if not treated early with chelation therapy. Lethargy, laboured breathing and watery and greenish diarrhoea should all be checked out by the vet if onset is sudden after a bird has had access to free flight around a room.
Other nutritional considerations
A common non-infectious condition seen in pet budgies and cocktails not provided with opportunities to shell seeds or to gnaw and chew on hard objects is an overgrown beak, necessitating trimming by a veterinary surgeon (Kubiak, 2020).
Many owners think that providing cuttlefish “bone” is a good source of calcium for their avian companions, but unfortunately, this is not in a form that is easily digestible in the avian gut. All caged birds need to absorb calcium from their food, which is assimilated across the mucosa of the digestive tract. Therefore, calcium supplements can be provided for seed-based diets. No supplementation is generally needed for birds on pelleted diets provided they are consuming the correct amount of pellet.
In all breeding female birds, egg binding can occur if the bird is fed an incorrect diet (Moustaki, 2007), specifically with diets involving a lack of calcium which results in soft-shelled eggs that are difficult for the female bird to lay. Veterinary attention should be sought as soon as possible to ensure the condition is not fatal.
