Introduction

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Birds are unique in the way they respond to and exhibit their

illnesses.  You, as a bird owner, must appreciate this fact if

you are to recognize illness in your birds and respond promptly

to their needs.



All animals have limited ability to physiologically compensate

for one or more medical problems, involving one or more organ

systems.  When the animal can no longer compensate, obvious

signs of illness are expressed.  The term for the period during

which an animal is sick but does not show obvious signs of

disease is subclinical illness.  Caged birds seem to have an even

greater compensatory ability, and subclinical illness is common

in birds.  Birds, in fact, appear to hide signs of illness.

This is actually a preservation response, rather than a

deliberate or conscious act.



This preservation response is, no doubt, an evolutionary

adaptation.  Many birds are flock dwellers, with social

hierarchies (pecking orders).  A individual struggling to

maintain its position in this hierarchy tends to be eliminated

from the group.  This tendency for members of the same species to

harass weaker members of the group eliminates the weaker members'

genes from the gene pool, thereby strengthening the species'

chances for survival.  In spite of the benefits for the group,

it behooves the individual to look healthy for as long as

possible to avoid this harassment.



Animal behaviorists believe that the evolutionary establishment

of communal groups (flocks, herds, etc.) resulted from the

increased survival of individuals (more eyes and ears to detect

predators and other life-threatening situations).  Predation

often eliminates the weakest members (very young, old or sick)

of the group.  Again, it behooves the individual to stay as

healthy as possible, for as long as possible, to avoid

attracting predators to the group and predation on itself.