Abnormal behaviour of birds in captivity

Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for captive birds of that particular class or age.

Each of these behaviours have been tied to physiological stress (i.e., extremely enlarged adrenal glands) likely caused by housing conditions in captivity.

[4][8][9][10] Stereotypies are invariant, repetitive behaviour patterns with no blatant function or objective, and seem to be restricted to captive and/or mentally-impaired animals.

[11] Stereotypies are the result of inability of an animal to perform a normal behaviour due to external environmental conditions or circumstance.

A common stereotypy in laying hens is pacing which involves the animal constantly walking back and forth in a seemingly ritualistic manner due to no access to a suitable nest site.

[11] The pacing stereotypy is also hypothesized to arise from intentional movements of escape, specifically in captive animals such as birds.

The overabundance as well as lack of stimulation associated with the sub-optimal environment of captivity are the common factors amongst development of stereotypy behaviours in birds.

[36] Several parrots living in captivity monitored during a study have displayed behaviors consisting of screaming excessively and biting.

[39] In addition, it has been suggested that keeping caged birds in pairs or small groups may reduce the development of abnormal behaviours, however, little quantitative evidence has thus far been collected to support this claim.

[40] Currently the dominant method for rearing domesticated birds is "hand-rearing" which requires chicks be separated from their parents for periods of time up to several months.

[41] For example, normal sexual and habitat imprinting is altered in both male and female birds as a result of maternal separation, as well as individual ability to adapt to stressors within the environment.

[42] Therefore, socially deprived juveniles may exhibit abnormal vocal and consequent mating behaviours which may be detrimental to their survival.