The most commonly kept pet bird species are psittacines (parrots) and passerines (perching birds like canaries and finches). These two groups of birds comprise nearly 6,000 of the more than 9,000 recognized avian species. Of the parrots, there are actually more than 350 species recognized. Despite worldwide popularity of these birds, little information is definitively known about their nutritional requirements.
For most companion bird species, much of what has been recommended has been extrapolated from studies using poultry. While poultry studies can provide general guidelines for feeding pet parrots, this data does not take into account the differences between poultry and parrots (and furthermore, among parrot species themselves) in gastrointestinal tract anatomy and physiology that determine how a particular species utilizes particular foods.
Even among the parrot species, which generally eat plant-based diets, wild birds can be classified according to what part of the plant they consume. There are four main groups:
Grainivores (grain or seed-eating birds, like budgerigars and cockatiels)
Frugivores (fruit-eaters, like many macaws)
Nectivores (nectar eaters, like lorikeets and lories)
Omnivores (that eat a variety of different kinds of foods, including animal matter, like many cockatoos and parakeets, but not budgerigars).
Even among grainivores, there are small birds that tend to select generally lower protein grass seeds and large birds that usually go for higher protein shrub-based seeds. Importantly, the digestive anatomy of each of these groups of birds has evolved in response to and is reflective of the type of food they consume in the wild.
Finally, in addition to general dietary classifications that can be made based on wild bird feeding behavior, further dietary distinctions can be made for parrots based on availability of food in the wild, the bird’s gender, her age, her reproductive status (egg-laying in females, feeding young, etc.) and her activity level. For pet bird species, it is nearly impossible to replicate the diets consumed by their wild bird counterparts because of the variety of seeds and other specific foods that are generally unavailable or available only during certain seasons.
Given the paucity of scientific knowledge about what the actual nutritional requirements of different captive parrot species are, most nutritional recommendations for pet birds are based on anecdotal information that is published in literature for lay people and that is taken at face value as correct by pet bird owners. Much of this information is incorrect at worst, or unsupported by any scientific evidence at best. Further controlled scientific studies must be done to determine the general dietary requirements for different parrot species.
Until these studies are accomplished, to help ensure that parrots’ basic nutritional needs for broad classes of nutrients like fat, carbohydrates, protein, vitamins and minerals are met, avian veterinarians have recommended feeding nutritionally complete formulated diets that contain an optimum estimated concentration of essential elements as extrapolated from poultry studies, wild bird feeding behavior and years of study of captive birds’ health while these birds were fed various different food combinations.
Formulated diets are generally either pelleted or extruded products with added vitamins and minerals. Pelleted products are generally compact and are of a uniform (often smooth tubular) shape, while extruded products are produced at a higher heat and may contain a higher fat content and a different texture than pelleted products.
While most avian veterinarians recommend formulated products as the mainstay of pet parrots’ diets, the addition of a limited amount of high-water/low-calorie foods such as most fruits and vegetables will not significantly change the amount of formulated product pet birds consume. However, when bird owners over-supplement formulated diets with large amount of vegetables, fruits and seeds, the calories in these foods will likely decrease the consumption of formulated products and could predispose birds to nutrient deficiencies and malnutrition. Feeding small amounts of water-rich fruits and vegetables (generally less than a third of the total food intake) will provide some variety to a bird’s diet without compromising the benefits of consuming the formulated product. Formulated product manufacturers’ recommendations regarding feeding proportions should be strictly followed so that birds can benefit optimally from these products.
For proteins, seeds are generally deficient in several essential amino acids — the building blocks of protein — required by parrots to stay healthy. Even seemingly more nutritious protein-containing foods may contain an adequate total percentage of protein to meet a parrot’s overall protein requirement but may be lacking in certain critical amino acids. Recommendations regarding dietary protein levels for specific species have yet to be determined for all pet parrots. Among grainivorous species, protein requirements have been established in budgerigars and cockatiels. These requirements have been shown to increase with increasing body size, so that higher levels of protein (depending on the protein source) may be required by larger parrot species. Conversely, certain naturally frugivorous birds, such as Pesquet’s parrots, seem to require much lower levels of dietary protein.
In addition to species, specific stages in parrots’ lives — growth, reproduction and molting — may alter a bird’s protein requirements. Birds that do not receive adequate amounts of essential amino acids may lose weight, become more susceptible to infections, and develop de-pigmented and/or abnormally structured feathers with so-called "stress bars.”
Conversely, anecdotal reports that over-supplementation of parrots’ diets with protein can lead to kidney dysfunction and gout have not been supported by experimental evidence.
Another category of essential nutrients is fat. Fat provides not only energy but also carries essential fat-soluble vitamins A, D, K and E. Fat contains building blocks called fatty acids, some of which are critical in birds’ diets. Fat and energy requirements for pet birds vary depending on the bird’s activity level, age and to some degree on the natural diet of the bird’s species in the wild. Specific, accurate daily energy requirements have been determined only for budgerigars; other species-specific data is lacking.
Some species, such as the macaw, are known to consume higher levels of fat (predominantly from palm nuts and fruit in the wild). Captive macaw chicks become thin and stunted if they consume inadequate calories. More commonly, pet birds consuming excessive amounts of fat (especially in the form of uniform seed-only diets such as sunflower or safflower seeds) may become obese and develop secondary health issues, such as atherosclerosis (deposits of fat within arteries leading to hardening and decreased ability to pump blood), high-cholesterol, stroke, fatty-liver disease and arthritis. Pet budgerigars, Amazon parrots, and rose-breasted and other cockatoos are notorious for becoming obese, especially if they are fed seed-only diets.
Carbohydrates — digestible sugars and starches and indigestible fiber — also provide energy in parrots’ diets. Digestible carbohydrates serve as a readily available source of energy for birds, since they are more quickly digested than fat. Dietary fiber, such as that found in the hulls of seeds, is typically not needed at high levels in parrots’ diets; in fact, unlike in people that benefit from high-fiber foods, birds that are designed to fly do not achieve any benefit from the addition of fiber to their diets. Such fiber would slow down the passage of food through their intestinal tracts, increase stool volume and water content, and decrease overall dietary nutrient digestibility, making it more difficult to fly. Thus, pet parrots’ requirement for dietary fiber is presumably very low.
Another essential category of nutrients in parrots’ diets is vitamins and minerals. Several vitamins and minerals are required to maintain parrots’ health, and complex relationships exist between several of these nutrients; thus, they must not be considered individually but in relationship to each other.
A perfect example is the interrelationship between the minerals calcium and phosphorus and vitamin D. Birds require calcium in levels higher than any other mineral. Calcium is necessary to mineralize bone (especially important in growing birds), to fuel enzymatic reactions throughout the body (in digestion, metabolism, the immune and nervous systems, and other critical processes) and to form eggshells.
Most seeds fed to pet birds contain less than 0.1-percent calcium, while grains such as millet, canary seed and corn contain less than 0.03-percent calcium. Excessive fat consumption by birds, as with seed-only diets, can bind up calcium and limit a bird’s intestinal absorption, leading to calcium deficiency manifested as weak and fractured bones in growing birds (rickets) and decreased appetite/feather chewing/lethargy in adult birds. It can also manifest as egg malformation/egg binding in egg-laying birds. Some species may be more susceptible to calcium deficiency than others. African grey and timneh grey parrots seem to be unable to mobilize calcium from their bones to maintain normal blood calcium levels; prolonged deprivation of dietary calcium commonly leads to bone fractures and seizures in these species.
Levels of dietary phosphorus in birds can significantly affect dietary calcium absorption. Phosphorus is essential to digestion, maintenance of the body’s acid-base balance, energy metabolism, and the formation of both bones and eggs. High levels of dietary phosphorus can inhibit calcium absorption leading to all the signs associated with calcium deficiency. Thus, the calcium to phosphorus ratio is as important to birds’ health as are dietary levels of each of these minerals. The optimal calcium to phosphorus ratio in an adult, non-egg laying bird’s diet is approximately 2 to 1. Seeds contain an excess of phosphorus, so an all-seed diet can undesirably offset this ratio.
Vitamin D also plays an essential role in dietary calcium absorption. The exact requirement for vitamin D in pet birds is unknown. The active form of vitamin D in parrots is vitamin D3 (cholecalciferol). In birds, ingested vitamin D precursors are converted to active D3 in birds’ skin when they are exposed to ultraviolet light (as in sunlight). Birds that either consume low dietary levels of vitamin D or are never exposed to direct UV light are more at risk of suffering from the effects of vitamin-D deficiency including soft beaks, bone fractures, soft-shelled or shell-less eggs, increased thirst and urination and blackening of feathers. Conversely, over-supplementation with vitamin D (or calcium) can lead to calcium deposits in kidneys and secondary kidney failure.
Another vitamin that is critical in birds’ diets is vitamin A. Vitamin A is essential in birds for proper growth and reproduction and to maintain healthy skin, feathers, vision and respiratory tract and immune function. The exact levels of vitamin A required for all pet bird species aren’t yet known, but some research has been done in cockatiels giving general dietary guidelines.
Lack of vitamin A is very common in pet birds on predominantly seed diets, as seeds contain little vitamin A or its precursor, beta-carotene (which birds can convert into vitamin A). While all birds on low-vitamin A containing diets are at risk of suffering from hypovitaminosis A, African grey and Amazon parrots seem especially susceptible. Signs of vitamin-A deficiency in birds include decreased appetite, increased susceptibility to infection, discharge from eyes and nose, poor growth, abnormal feather formation, white plaques in the mouth or crop and redness and sores on the bottoms of feet. Excessively low or high levels of vitamin A fed to cockatiels also affected how frequently they vocalized.
Vitamin E is also essential in parrots’ diets. Vitamin E is critical to normal nervous system and muscle function. Vitamin E deficiency is uncommon with seed-based diets, as most seeds contain adequate amounts of vitamin E. Signs of vitamin E deficiency reported in cockatiels include muscle weakness, imbalance, twisted necks, and paralysis. Many fruits have very low levels of vitamin E; thus, diets containing excessive fruit may contribute to vitamin-E deficiency in birds that are not naturally predominantly fruit-eaters. Vitamin E is unstable in food and can degrade in formulated products if not maintained with preservatives. Thus, it is critical not to use these products after their expiration dates so as not to risk vitamin-E degradation and subsequent vitamin-E deficiency in birds fed these products.
Other vitamins parrots require in their diets include vitamins K, B and sometimes C. Vitamin K is necessary for normal blood clotting. Bacteria in birds’ intestinal tracts synthesize vitamin K; thus, vitamin-K deficiency is rare unless birds are on long-term antibiotics.
Specific studies on parrots’ requirements for B vitamins have not yet been performed. Therefore, studies in poultry are used as guidelines. Vitamin-B deficiencies in birds can lead to stunted growth, weakness and poor feathering. While most seeds generally contain adequate amounts of most B vitamins, vitamin B2 (riboflavin) is found at very low levels in seed. Riboflavin deficiency, reported in birds on seed-only diets, can lead to the development of curled toes in chicks.
Finally, vitamin C requirements in birds vary significantly by species. Most parrots and many passerine birds synthesize vitamin C and therefore do not require large amounts in their diets.
There are a few other trace minerals birds require in their diets that can lead to health problems if they are lacking. Iodine deficiency can lead to goiter (swelling of the thyroid gland) more commonly reported in older budgerigars. Feeding excessive amounts of peanuts and cruciferous vegetables in the Brassica plant family (cabbage, cauliflower, broccoli, Brussels sprouts and some types of seeds) may interfere with the body’s iodine utilization, and ingestion of large amounts of calcium can have an anti-thyroid effect, as well. Since the thyroid gland is within birds’ chests (as opposed to the neck in mammals), the swollen thyroid can press on the trachea and the esophagus, resulting in a squeaky voice and regurgitation. Treatment with oral iodine supplements generally resolves this condition.
In addition, iron is required by all birds for normal red blood cell production, but certain species, such as mynahs and toucans, are susceptible to iron toxicity from iron storage disease (hemochromatosis). These species have evolved genetically to absorb iron very efficiently from their food and as a result, they can accumulate large stores of iron in their livers and heart muscle, leading ultimately to liver and heart failure and death.
Consumption of ascorbic acid (vitamin C) increases iron availability in food and therefore should be avoided in species prone to iron storage disease. These species should be maintained on low-iron diets and should not be fed citrus fruits.
As this interaction between vitamin C and iron, or between vitamin D and calcium shows, there are many complex nutrient relationships within the diet, each of which needs to be considered to ensure the diet is balanced. Lack or imbalance of particular nutrients in a bird’s diet over the long term can lead to several clinical signs that may become more apparent during times of physiological stress, such as during growth, reproduction, molting and illness.
Until more detailed studies on the specific nutritional requirements of individual species in captivity are determined, the most balanced diet we can offer pet parrots is a commercially available formulated product, designed to meet the needs of pet parrots, supplemented with a limited amount of fruits and vegetables. I have recommended these products for two decades and have seen thousands of parrot patients thrive on them.
Loved this article? Check out these:
Bird Food Myths & Facts
Introducing Pellets To Your Pet Bird