*disclaimer*This post is based on a paper I wrote for an animal nutrition class, so it’s a bit long.
Parrots are primarily found in the tropics and often are associated with tropical paradise imagery. There are over 350 species in the order Psittaciformes, which are commonly referred to as parrots. This order is divided into 2 families (Koutsos 2001), Cacatuidae and Psittacidae. Cacatuidae contains cockatoos, cockatiels and corellas. Psittacidae contains lores, lorikeets, parrots, macaws, parakeets, rosellas, and love birds. Psittaciformes are some of the most common birds kept in captivity due to their high level of intelligence and distinctive physical form. A large number of zoos have parrot collections, and at large pet store retailers they are available as companion animals. Unlike other birds, they are not used for commercial use of their eggs, meat, or feathers. Therefore only the maintenance values are important in the feed formulation of these birds.
All of these parrots have specialized nutritional needs. As a result, most common cause of vet visits is improper diet (Torregrossa 2005). Therefore this paper will focus on the basic nutritional needs of parrots. Similar to horses, these diets have become adapted to human needs, and thus is not reflective of parrots in the wild. In the wild parrots eat roughly 70 percent seeds (Gilardi 2012) but their diets range from nectarivores to granivores (Matson 2006). Renton (2001) also observed a high flexibility in the diet of wild parrots. Pullianen (1972) found that birds do not select the foods based on their nutritional needs. Because these diets are so varied it is hard to produce a feed that meets the nutritional needs of all parrots.
I attended a lecture by Dr. Susan Smith on her research related to migrating birds and berry nutrition. Migratory birds spend up to four months a year in the process of migration. These migrations are to wintering grounds and breeding grounds. During these trips, physiological demands are much greater. These trips require very large energy reserves. 79 percent of these reserves come from fats.
These stores of energy are depleted and then restored at migratory stopovers. At these sites, refueling occurs. This must be rapidly done due to time constraints (must get to wintering ground before winter). Bird’s diets change during migration to be able to rapidly refuel. Birds eat large amounts of fruit. The benefits of eating fruit in place of their normal diet are fruit is high in fat and fruit is easier to hunt. There are limits birds have to eating fruit. One type of limitations are digestive. Bird’s digestive systems can only handle a certain amount of seed load. Also, some fruits contain a certain amount of toxins and the system can handle only so much. Other limitations are nutritional.
Fruit varies in energy and protein content. Some contain up to 40 percent fat, most of these include native species. As fat content increases, energy density also increases. A hermit thrush (Catharus guttatus) (that on average weighs 31.2 grams) would have to eat 18.8 grams of bayberry (Myrica sp.) (high in fat) or 90.7 grams of pokeweed (Phytolacca decandra) to fill the daily energy needs. Eating this much pokeweed is clearly not possible.
One of Dr. Smith’s studies tried to see if birds prefer certain fruits during autumn migration time. Nets were placed around berry bushes and the amount that natural falls off was measured. The nets were removed and the amount of berries eaten during different times of the year was measured. The amount of arrowwood (Viburnum dentatum) (high in fat) eaten increased during migration, were as the amount of chokeberry (Aronia sp.) (low in fat) eaten stayed the same.
Another study was done by Dr. Smith using the plasma metabolic profile (blood samples). These samples provide information on metabolic fuel use and energetic condition. Lipid metabolites indicate how mass has changed over the last several hours (showing refueling). Other metabolites provide more information. Plasma was also sampled at two different stopover sites to compare them.
These sits were the Braddock Bay Bird Observatory and Rochester Institute of Technology Bird Observatory. At Bradock Bay Bird Observatory there was 200% more ripe fruit and this was 83% native berries (tend to be higher energy). At Rochester Institute of Technology, there were only 10% native berries. Birds were sampled the same day and same time at these locations. It was found that at Braddock Bay Bird Observatory those birds had higher triglyceride levels. This proves that fruit is helpful in birds refueling.
Dr. Smith hopes to continue in researching the effects of fruit on birds. One study she wants to do is compare seasonal and site differences in fruits nutritional content. She also wants to look at if the bushes that provide fruit provide a year round value (such as a place to nest in or find insects). She wants to develop fruit fingers prints (light that comes off fruit when you shine a fluorescent light on it). This can be used to quickly tell if a fruit has high or low nutrients. Lastly, Dr. Smith wants to see if invasive species are so integrated into the system that removing then would cause harm to bird by removing a food source.