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[ Systems | Husbandry | Nutrition | Food Sources | Diseases | Emergency Care ]
Systems
1. Evolution- Prehistoric reptiles, having conquered the land, allowed birds
to emerge as the masters of the air. Evolutionary jumps such as regulation of a warm
body temperature, gliding, and ultimately flight resulted in the development of feathers.
From here, the systematic diversification of birds has resulted in 26 major orders
and over 9,700 distinct species. Birds inhabit every continent and almost every habitat
with the exception of the deep seas. Birds are uniquely adapted to the microenvironments
in which they live. Special adaptations have allowed them to thrive in other than
terrestial and aquatic environments. In order to understand avian species, it is
helpful to understand their anatomy.
2. Integument- Birds possess feathers as their protective covering which affords
them insulation and water repellence while granting light weight and brilliant ornamentation
for display. The trade-off is that feathers also require a tremendous amount of care.
Some birds, such as waterfowl, spend most of their time waterproofing their plumage.
The skin of birds is very thin, almost transparent, yet quite vascular. The feathers
are not randomly placed but arranged in longitudinal rows known as pterylae. Unlike
mammalian skin, bird skin offers little protection except on the legs and feet. There
is only one gland present on some birds, the uropygial gland at the base of the tail.
Without sweat glands, the skin is of little use in thermoregulation.
3. Skeleton - Pneumatic, or hollow, bones in most avian species allow buoyancy
in the air and assist ventilation. The jaw has been replaced by a lightweight keratinaceous
beak and the spine is fused along the thoracic vertebrae and along the lumbar and
sacral vertebrae; all in order to allow for flight. The clavicles are fused to the
sternum forming the "wishbone" and connect to the triosseal canal to help
support the shoulder joint. The coracoid bone is unique to birds and provides the
muscular anchor for the downbeat of the wings. Unlike mammals, birds have bone processes
between their ribs which spring the keel or breastbone outwards expanding the chest
and inspiring air. The abdominal muscles pull the breast towards the body causing
expiration.
4. Respiratory System - As stated earlier, pneumatic bones provide a lightweight
skeleton and act as additional resevoirs of air to aid in buoyancy, thermoregulation
and respiration. Attached to the lungs are air-filled membranes called air sacs which
are the primary resevoirs of air and provide most of the bird's bouyancy. Birds lack
a diaphragm and must move the breast outward in order to inspire air. Unlike mammals,
the lungs do not expand and contract within the chest and are actually attached to
the ribs.
5. Special Senses- Mammals have one area of high visual acuity on the back
of the eye known as the fovea, but birds may have two foveas which are used in different
situations. One fovea may be used when a bird is perched, and others may be used
during flight, under water or for near vision when feeding on the ground. The avian
eye is also very large and consequently requires a modification to keep it inflated.
Birds have scleral ossicles which are small bones that maintain the shape of the
large eye. Although ear flaps are not present around the external auditory canal,
many species have adapted facial disks or facial grooves which channel the sound
to the ear. Owls and hawks are the most obvious examples. Oddly, most birds lack
sensitive olfaction (sense of smell) but most have an acute sense of taste.
6. Reproductive System- Laying eggs allows a hen to maintain very little weight
once the egg is laid. Most birds take weight conservation to the extreme and possess
but a single ovary and a single uterine horn. Laying eggs also requires birds to
eliminate waste in the form of uric acid, a concentrated, non-toxic crystal. Urea
excretion requires large amounts of water to eliminate waste but uric acid concentrates
the nitrogen waste products safely within the egg.
7. Intelligence- Some parrots are thought to have the intelligence of a three
to four-year-old child but the intellectual development of a six-month-old. Consequently,
these animals must be treated like young people and provided with environmental enrichment.
A monomorphic food like pellets or sunflower seeds is not enough for the nutrition
for the bird or for its psychological well-being. Parrots require daily attention
either from a cagemate or from its caretaker. What you provide them is all they get,
so give a lot.
[ Systems | Husbandry | Nutrition | Food Sources | Diseases | Emergency Care ]
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