*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.
Primary producers in all of these ecosystems vary. In rainforests, the primary producers include trees, shrubs, and epiphytes. An epiphyte is a plant that grows on another plant but it not directly parasitic. In mangroves, they are epiphyte and mangroves. The term mangrove describes how the trees live, it is not a taxonomic term. It simply describes a tree that lives in salt water. In a reef, the primary producers are corals, seagrass, and macroalgae (seaweed). Interestingly corals are also predators of the reef. The algae they are in a symbiotic relationship (zooxanthellae) with undergoes photosynthesis during the day. At night they hunt small organisms in the water and spear them with tiny barbs.
Herbivores (or primary consumers) in the mangroves, rainforest, and reefs all vary. In rainforests, these include birds, monkeys, agouti, tapir, butterflies, and sloths. In the mangroves there are fewer herbivores, these include mollusks and crabs. In the reef system, most organisms are herbivores. These include coral, smaller fish, sponges, plankton, and mollusks.
The one common characteristic that the tropics have in common is that the temperature is warm. The daily temperature usually changes more than the temperature average of the year. This is because the sun falls more directly on the topics than on other regions. However, depending on the region there will be changes in rainfall. Rainforest receives more rain than tropical savannas (more than 200 cm a year). Because of this savannas are more suitable to fires in the dry season. Some plants have adapted to be able to survive these fires, and often have visible scarring from fires. The animals have also adapted to the dry conditions. Because droughts are localized the animals migrate around the savanna. The soils are often acidic and are poor in nutrients. The soils are sandy and coarse textured. In addition, some savanna may become waterlogged during the year so the plants have to be adapted. For this reason, there is less plant diversity in savannas.
Rainforests, on the other hand, have to deal with excess moisture. Moisture can cause fungus and molds to grow. Some plants have developed drip tips because of this. Drip tips are sharp points on the end of a leaf that let water drip off the leaf. Leaves are concavely shaped so that water will run off of them. Leafs also have smooth edges rather than teeth to prevent water build up. Water build up would cause fungi and molds to grow on the leaf which would block sunlight and decompose the leaf. The soil is often moist and clay-like. Many monkeys are well adapted to live in the rainforest. They rely on the fruit which is in constant supply. In addition, new world monkeys have developed tails so they can easily navigate the tall canopy. Other animals have adapted to the heat by becoming nocturnal. Bats are an excellent example of this adaptation.
Like the savanna and the rainforest, coral reef requires fairly specific environmental factors in order to exist. The temperature is usually between 21-29 degrees Celsius. The reason this range is idea is that coral is actual a mutualistic relationship with algae called zooxanthellae. If the temperature increases too much then the zooxanthellae starts to produce toxic compounds to the coral and so the coral has to kick it out. Nutrient levels must be low because otherwise, microalgae will out-compete the corals. This is why the coral must be in a relationship with zooxanthellae because it lives in nutrient-poor water. In order for the zooxanthellae to undergo photosynthesis, the water must have a high light availability. Plating coral has evolved its shape so that it can absorb more light because it has a large surface area. In addition, the water cannot be too acidic or the rate of decalcification will be too great for the coral to form. The coral reefs provided great nursing habitat for dolphins, and whales raising their young. However, they do not have much food. Therefore these animals have adapted to use the reef as nursery habitat but migrate north to waters with more food. Because coral reefs have nooks many animals, particularly fish have adapted to live in these. They have flat bodies that are highly maneuverable.