by Fern Van Sant on 06 December
Avian reproductive behaviors observed in the wild......such as pair bonding, courtship regur...
We are currently witnessing the swiftest mass extinction in geologic history. Those of us who have chosen to locus our talents on psittacines now find that we are in unique and critical position; stewardship of parrots now has global significance. It is likely that our best chance to ensure the survival of parrots lies with the ability of the avian veterinary community to create effective management strategies for captive birds. In order to accomplish this, we must first look to the natural world to determine the needs of the species we are attempting to manage. We must then guide pet owners and aviculturalists to planes of management that will promote the long term health and survival of their captive birds.
For those of us specializing in parrot (avian) medicine, it is becoming increasingly clear that many of the medical problems we deal with are, at least in part, a consequence of stresses created by removing the birds from the habitats to which they are adapted. Only now are we beginning to understand the need to incorporate the basic ecological needs of our captive animals into our management strategies and only now is the requisite information becoming available.
The inherent beauty and intelligence of the psittacines has long endeared them to humans. As a result of this endearment a large live bird trade has developed to provide people with parrots from around the world, Unfortunately, in some instances (especially among illegal exporters), an overwhelming concern for profit has overruled concerns for the welfare of the birds themselves.
With the affluence of the 70s and 80s, parrots became more common as pets in North American homes. Most of these birds were managed by the provision of little more than a cage (or perch) with seeds for food. They lived a sedentary existence with little opportunity to exercise or bask in the sun. Often they were confined to rarely cleaned cages and forced to breath second-hand smoke, while their owners worried that an unnoticed draft might doom their pet.
These were dark ages in parrot management. Why did such shortsighted practices persist for so long? They persisted because the birds survived. They didn't thrive, but they did survive. At least for a while. Though we recognized that parrots were long-lived creatures, we failed to notice when few of them were living to be even twenty years old; ten years became a milestone. All too often death came suddenly, without warning, without obvious cause.
But the loss of life resulting from malignant management of pet parrots pales in comparison to that associated with loss of natural parrot habitat around the world. We are currently witnessing the swiftest mass extinction in geologic history. Harvard Biologist, E. 0. Wilson estimates that 27,000 species disappear from the earth each year. That is equivalent to 74 species extinctions per day or three per hour. Over the past two millennia we have lost 1/5 of the bird species worldwide. The International Council for Bird Preservation (ICBP) estimates that 11 per cent (over 1,000) of the remaining bird species are presently endangered. All but three of the 332 remaining species of parrots on Earth are listed as threatened or endangered. As this rate of loss continues, it is increasingly more important that we employ effective management strategies for domesticated parrots. Aviculture and the pet parrot trades may one day represent the last refuges of parrot species.
If we are to create an effective management strategy, we must first look to the natural world to determine the needs of the species we are attempting to manage. Not only have we separated our pet birds from their native habitats, in many cases we have also, through well intentioned but misguided management practices, separated them from their basic biological requirements. We must bear in mind that every species has been shaped by its native environment over the course of its evolution. If we continue to ignore the fundamental needs of the species we attempt to manage, we will inevitably doom our captives to live their short lives in poor health.
In common with their closest relatives, the pigeons (order Columbiformes), many species of parrots are well adapted for feeding on seeds and grains. However, over the 30 million years of evolution since parrots first appeared in the fossil record, many species have diverged and specialized as they adapted to changing physical conditions and biotic associations. An extreme example of this sort is the specialization seen in the lories and lorikeets (Subfamily Loriinae) that feed primarily on pollen and nectar. In these species the musculature of the gizzard, which is so well developed in their seed-eating relatives, has been largely lost.
Today the majority of Psittacine species are native to the tropics of the southern hemisphere. Although they are most common in the canopies and along the margins and watercourses of lowland tropical rain forest habitats, some species are also found in cloud forest? Dry forest and savanna habitats. Each of these habitats provides unique opportunities and each exerts unique selective pressures on its inhabitants. Specialization and diversity are the hallmarks of tropical rain forest evolution. Specialization facilitates efficient exploitation of resources, reduces competition and increases diversity. Where specialization is species specific, it often increases the interdependency of the species involved and thus selects for reciprocal benefit in the interaction.
While some parrot species, such as the rose-ringed parakeet (Psittacula krameri Scopoli) range across continents, others like the grey-cheeked parakeets (Bootogeris ovrrhonterus Latham) have a very limited natural distribution. In general, the species with the most restricted ranges tend to be confined on ocean-bound islands; however, some species may be restricted by the distribution of the plant species on which they are specialized. The range of the African grey parrot (Psittacus erithacus Linne), for example, corresponds to the distribution of the African oil palm (Elseis guineensis), a favored food source.
By determining whether a species is restricted in nature to a narrow well defined habitat or ranges over a variety of habitats, we can often predict the outcome of our efforts to maintain that species in captivity. Species whose ranges extend across different habitats must possess a broad range 01 physical tolerance to survive. As a consequence it is likely that such species will be tolerant of the exigencies that accompany life as a captive animal. This is clearly the case with our success in maintaining budgies (Melopsittacus undulatus Shaw), cockatiels (Nymphicus hollandicus Kerr) and scarlet macaws (Ara macao Linne). In contrast, species with limited ranges and well defined habitats are likely to have evolved restrictive dependencies and are likely to be less tolerant of changes in environment. The health problems of captive grey-cheeked parakeets may be an example of this relationship.
The practical limitations of our own existence often restrict what we can do to provide a healthy environment for our captive birds. Clearly, we cannot recreate rain forest habitats in our living rooms. There are, however, a few obvious changes in our management practices that can produce good results.
Since most parrots are canopy residents in their native environments, they are typically exposed to intense tropical sunlight during much of their daily activity. Providing adequate exposure to sunlight or an artificial source of full spectrum light (such as that provided by Vita-LitesTM) can be important in the conversion of vitamin D3 from its inactive sterol precursor. Birds secrete the precursor of vitamin D3 in the oils of their preen glands and spread it onto their feathers where it is photo activated by exposure to sunlight. They then either ingest the activated vitamin during further preening or absorb it directly through the skin. Vitamin D is critically important in calcium absorption in the intestine and its regulation in the circulatory system. A more widespread appreciation of this relationship could reduce the frequency of hypocalcemia in captive parrots.
As is the case with most birds, parrots are adapted to a lifestyle that includes tremendous aerobic muscular activity. Forcing such natural athletes to lead a sedentary existence within the confines of a cage is likely to cause muscular atrophy, excessive fat accumulation and increased health risks similar to those observed in hospitalized humans. Full flight has obvious problems in increasing the risk of injury and/or escape; however, outdoor exercise enclosures or large climbing structures may provide an adequate compromise.
Many parrot species are adapted to humid tropical environments where they are often rained on several times in the course of a day. Confinement In the dry air environment of a heated home during temperate climate winters can adversely affect respiratory functions and feather condition. Fortunately, this problem can be reduced by regular (daily) misting or bathing in a shower. The use of household humidifiers appears to provide a simple solution, however, experience has shown that such devices can increase the concentration airborne bacteria, which can have detrimental effects.
It is also important that clean drinking water be constantly available for the captive parrot. This is especially crucial when water is not a major constituent of the food provided. The water that flows through many tropical rain forest ecosystems tends to be quite acidic. In contrast, the domestic water supplies of most North American cities tend to be alkaline Acidification of parrot drinking water by the addition of a few drops of vinegar can often make a difference.
In their native habitats, most parrots supplement their otherwise "seed" based diets (seeds, grains, nuts and/or legumes) with leaf buds, flowers, fruits, berries and insects. Some parrots, such as the sulphur-crested cockatoo galerita Latham), are also known to ground feed on roots and tubers. Such supplementation provides ample beta-carotene, sugar, and hemicellulose which are often lacking in seeds and which are probably needed to provide a balanced diet and proper alimentary functions.
The consumption of some plant tissues (e.g., leaf buds and immature fruits) that contain high concentrations of secondary (plant defensive) compounds, such as terpenes, alkaloids and phenolics (tannins), may also create major metabolic challenges for parrots. Geophagy (literally, earth eating) which has been observed in over 15 species of parrots including five species of macaw) may be an adaptive mechanism that the birds have learned to employ to absorb toxins (such as alkaloids) as well as excess fatty acids in their diet. Geophagy may also provide supplementary mineral salts such as calcium. At present little information is available on the role of mineral salts in the diet of parrots. The short gastrointestinal tracts and porous kidneys of parrots, which appear to be adaptive in the excretion of large potentially toxic molecules (e.g., alkaloids), may predispose the birds to chronic salt depletion problems.
Nutrition is typically the aspect of most management strategies over which we can exercise the most control. As a consequence of their adaptations for flight, most birds must rely on highly concentrated foods to meet their nutritional needs. It is important to provide a diet that is balanced to meet the needs of the bird. Just as we humans must balance our diet by consuming foods that nutritionally complement each other, we must provide our captive parrots with complementary foods that meet their general as well as their specific needs. It is not enough to maintain a parrot on a strictly seed based diet, especially when the seeds we provide are high fat seeds from temperate oil-crop plants (e.g. sunflower, safflower and peanut).
Psittacines feeding in the canopy trees of tropical forests have access to the seeds and nuts of many species of fruit bearing trees. In comparison to the seeds of sunflower, safflower and peanut, many of the tropical seeds and nuts contain high ratios of protein to fat. They also differ in the types of fat they contain. Whereas most tropical nuts contain saturated fatty acids, which are stable in heat and light, the polyunsaturated fats of temperate climate seeds quickly become rancid with such exposure. Rancid polyunsaturated fatty acids (e.g., linoleic acid) have recently been implicated as immunosuppressive substances and they appear to play a role in micro vascular disorders.
Work by Dr. Helga Gerlach in Germany has demonstrated a unique pattern of B-carotene absorption in parrots. Whereas mammals typically cleave B-carotene into two molecules of vitamin A prior to absorption through the intestine, it appears that parrots may be able to absorb dietary B-carotenes directly. Thus, the provision of B-carotene in the diets of captive parrots may be important for the maintenance of adequate levels of vitamin A and the treatment of syndromes associated with hypovitaminosis A. B-carotenes have also been shown to have potent antioxidant properties.
Hemicellulose, an important component of plant cell walls, has been used effectively as a laxative in the treatment of intestinal disorders. The seeds (psyllium husks) of some plantains (Plantago ovata and P. afra) contain high concentrations of hemicelluloses that, when ingested, absorb water to form a mucilage which helps soften the stool and facilitate its passage through the intestine. The mucilage is also thought to enhance intestinal absorption, bind bacterial toxins, reduce the incidence of gut lesions and improve peristalsis. Addition of hemicellulose to the diet of captive parrots should help compensate for the low water content in their food and reduce gastrointestinal transit time.
Our ability to develop an effective psittacine management strategy depends on our ability to synthesize and apply information from many sources. Such a plan must be based on a solid understanding of the needs of the individual species. It is unlikely that any one plan will meet the needs of all the diverse species we presently maintain in captivity. However, if we design our strategy to meet the needs of the more fastidious parrots, we will create a management umbrella under which most species will thrive. As our awareness of the unique needs of each species improves, we should be able to modify our strategy to meet those needs.
At present, the use of formulated diets (supplemented by the provision of fresh fruits and vegetables) probably holds the greatest promise of success. The use of prepared "complete" foods can help overcome the natural tendency of captive parrots to binge feed on favored foods that do not provide a balance of nutrients. Reliance on a formulated diet offers a solution to the picky habits of some birds, however, it also poses a risk in that the unique needs of some species may not be met with a single formula. Research and development of effective formulas thus becomes critical to their success. Production of a food of consistently high quality is also imperative.
In my experience with formulated diets, two products (Nutri-AnTM and Harrison's Bird DietTM) stand out with regard to attention to research, Quality control, palatability and results. Nutri-AnTM, a product of the Lafeber Co. is limited to veterinary distribution and has been an industry standard for many years. My experience with the Nutri-AnTM diet over a five-year period indicates that in conjunction with fresh fruits and vegetables, it will support and maintain health in even the most fastidious species. I have never found problems with quality control nor have I observed any adverse effects due to this formula.
Harrison's Bird DietTM (HBD) has recently emerged as an innovative alternative. HBD has managed to blend the tastes and textures parrots seem to like with an array of ingredients that is designed to meet their unique requirements. Harrison's is the only available formula that is prepared from certified organic ingredients. This not only ensures freedom from pesticide residues but also takes advantage of a state of the art approach to the growing and processing of quality food. It seems to be the bird's bird food, relying heavily on foods we know to be present in the native environments of the parrots. The addition of spirulina (a blue-green bacterial source of protein and minerals) and psyllium (a source of hemicellulose) in this formula may be particularly important in the success of this food. There seems to be a profound immune supportive effect to HBD. It is unlikely that this is due to any single component of the product; it seems to be a result of the combination of the ingredients and the lack of potentially toxic residues.
I have limited my recommendations to these premium, veterinary distributed products for several reasons. First, I am of the opinion that the way to approach the nutrition of parrots is to meet the needs of the most fastidious species and let the more resilient species enjoy the benefits. Second, a consistent high standard of quality is needed. Quality control is an issue that should concern any professional who recommends a formulated diet; we must rely on the manufacturer to provide a safe and effective product. Third, client education concerning parrot biology, physiology and personality is a prerequisite for the success of any parrot management strategy. Most people are poorly informed about even their own nutritional requirements and the effects nutrition can have on health; so, without appropriate instruction, how can they be expected to manage the nutritional requirements of a parrot? The grim lessons of traditional seed management need to be explained in understandable terms. Parrot owners must also understand that they are ultimately responsible for the nutrition and general management of their parrot and that proper management is the key to health maintenance.
Those of us that have chosen to focus our talents on psittacines are in unique and critical position. These days, stewardship of parrots does have global significance. It is likely that our best chance to ensure the survival of viable populations lies with the avian veterinary community. The only way to do this is to guide aviculturists and pet bird owners to planes of management that will promote the long term health and survival of their captive birds. With the gun of mass extinction turned to the parrot's head, it is imperative that we synthesize a workable plan. Much of the information we need to do this is already available in the published studies of biologists, nutritionists, avian veterinarians and aviculturists. We must access this information and put it to use in developing effective management strategies for our captive parrots. If not now, when? And if not us, who?
1. FORSHAW JM: Parrots of the World, 3rd ed. Melbourne, Australia, 1989.
2. FORSYTH A: Portraits of the Rain Forest, Ontario, Canada, 1990.
3. GOULDING M: Amazon, the Flooded Forest, New York, NY, 1990.
4. HAAS EM: Staying Healthy With Nutrition, Berkeley, CA, 1992.
5. HAMILTON K: Clinical Pearls in Nutrition and Preventative Medicine, Sacramento, CA, 1993,1992,1991
6. KING, WB: Endangered Birds of the World (lCBP Bird Red Data Book), Washington DC, 1981
7. PROSSER CL: Comparative Animal Physiology, Philadelphia, PA, 1973
8. RICKLEFS RE: Ecology, Newton, Mass, 1973
9. SHORT LL: The Lives of Birds, New York, NY, 1993.
10. WILSON EO: Biodiversity, Washington DC, 1988
Fern Van Sant, DVM
For the Birds
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Avian reproductive behaviors observed in the wild......such as pair bonding, courtship regurgitation, cavity seeking, nest building, territorial ag...