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Avian nutrition is complex and is not as well understood as mammal
nutrition. With more than 9,000 avian species extant, the rehabilitator
is required to have a good understanding of foraging categories,
digestive systems, natural foods and acceptable substitutes.
| Hatchling
and Nestling Birds |
Hatchling and Nestling Birds are especially challenging to feed.
It is crucial to identify the species and research its natural history
and physiology so that the diet promotes normal growth and development.
- Precocial birds (e.g. geese, ducks, turkeys, etc.)
hatch with their eyes open and are feathered. Young of many species
are able to move about and peck at food, following their parents
and learning by example which foods are edible. Others may remain
in the nest, but pick up foods brought to them by their parents.
Precocial birds, depending upon species, may eat insects, grains,
seeds, plants, fruits, fishes, mollusks, etc., and their diets
should reflect what they eat in the wild. For some species, commercial
preparations are available (e.g. game bird starter, duck starter,
etc.), but natural foods should also be offered so that the birds
learn to recognize and manage foods upon which they will rely
after release. Provide drinking water, natural foods and make
available clean soil scattered with oyster shells or crushed sterilized
eggshells (for minerals).
- Altricial birds hatch in a much more vulnerable
and primitive condition than do precocial birds. Their eyes are
usually closed, their bodies bare or mostly bare, and they require
constant parental attention and feeding. Some (e.g. passerines:
wrens, sparrows) are fed from dawn until late evening, and in
rehabilitation, they require food at 20-minute intervals. Others
(e.g., columbids, psittacines) have large crops in which they
store food; the parents fill the crops with regurgitant, thus
there are fewer feedings per day.
Young altricial birds are fed foods that promote rapid growth.
Even youngsters of seed-eating species will, while in the nest,
be fed animal-based foods or regurgitant. Passerines, hummingbirds,
woodpeckers and many other neonates are fed an insect diet. Pelicans,
albatross, penguins, etc. are fed fish (or regurgitated fish).
Birds of prey (e.g. hawks, owls, eagles, etc.) are fed small pieces
of prey. Because animal-based foods such as these are deficient
in calcium, parents supplement chicks with calcium in the form
of small bits of eggshell, mollusk shell, bone, grit, etc., depending
on species. Altricial birds require dietary calcium to be 2% of
the diet, and dietary phosphorus must be present at 1% of the
diet. If dietary calcium and phosphorus are not balanced (and
if vitamin D3 is not added to the diet in lieu of unfiltered natural
or full-spectrum light), these birds will develop skeletal problems
(metabolic bone disease).
An article on hatchling and nestling passerine nutrition (with
diet recipe) can be ordered through IWRC:
Adventures in Avian Nutrition: Dietary Considerations for the
Hatchling/Nestling Passerines;
Astrid MacLeod and Janine Perlman;
Journal
of Wildlife Rehabilitation, Spring 2001; Volume 24, #1
An article on hatchling and nestling dove/pigeon nutrition (with
diet recipe) can be ordered through IWRC:
Cream of the Crop: An Improved Handrearing Diet for Hatchling
and Nestling Columbids;
Journal
of Wildlife Rehabilitation, Spring 2002; Volume 25, #1
Adult birds are much easier to feed than are hatchlings and nestlings.
Again, it is crucial to identify the species and research its natural
history and foods. As much of the diet as possible should be what
is eaten in the wild. Substitute foods must be similar in composition
to wild foods. Birds should have ad lib feeding and drinking opportunity,
and be provided with clean soil and calcium sources (e.g. grit,
crushed sterilized eggshells, mollusk shells, etc.).
When birds are admitted to rehabilitation, they should be fed what
they would be eating in nature, as their digestive enzymes reflect
what they have been eating. If they are to be weaned to a richer
diet, it will take at least a few days before their digestive enzymes
change and are at high enough levels to break down the new foods.
During this time, the bird may not be receiving adequate nutrition.
To prevent this, offer free choice of seasonal foods along with
new foods, so the bird can pick and choose as it adjusts. When the
bird is being released, it must be prepared to digest what is available
in the wild, thus it is imperative that it has adjusted to those
foods or it may not survive release.
Comparative Avian Nutrition:
by Kirk C. Klasing
This unique book covers all aspects of bird nutrition, bringing together research from such diverse fields as ecology, poultry production, zoo biology and biomedical science. It provides in-depth discussions of the physical and biochemical processes of digestion, the metabolic functions of nutrients, and the evolutionary adaptations to accommodate their wide ranging diets. The book emphasizes the quantitative nature of nutrition and the practical dietary requirements of captive and wild bird..
Hardcover
CABI Publishing, CAB International
ISBN:0851992196
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