The budgie’s cere turns brown when they are in breeding season (in females) and sickness conditions.
Besides, a female budgie’s cere gets a crusty surface texture during breeding seasons.
Female budgie’s cere turn brown during breeding seasons
During breeding season, a female budgie’s cere color turns to brown and cere surface has a crusty texture.
This transformation is a well-known characteristic feature of female budgie, which in breeding season.
This characteristic transformation (normal color to brown color) is not seen in healthy male budgies.
— Image by birds-online.de
Hormonal imbalances/changes
Budgie cere color is sensitive to hormonal levels.
In breeding season, both male and female budgie’s cere changes their color and textures.
Depending on the changes of the hormonal levels, budgie color changes time to time.
Cere color transformation is sensitive to only hormonal changes.
In males, cere color become more bright and darker than it’s normal (off breeding season) color.
In females, cere color become brownish color and cere surface gets a crusty texture.
Healthy young and adult budgie’s cere colors differentiate due to amounts of certain hormones in blood, which are called estrogen and testosterone during breeding season.
Testicular tumor
In most avian species like budgie, testicular tumor is a destructive sickness.
Budgies that have a testicular tumor, shows different sexual behaviors and their cere turn dark brown color.
Androgen production diminishes as the tumor grows.
Diminished androgen levels cause lack of color production on budgie’s cere. In lack of enough male hormone level, male budgie’s cere begins to turn its color to brown.
Estrogen-secreting sertoli cell tumor
Estrogen-secreting sertoli cell tumor is a hormone level disruptive disease in birds like budgies.
Estrogen-secreting sertoli cell tumor disrupts natural hormone level of a male budgie body by suppress testosterone hormone.
Suppressing testosterone causes excessive amount of estrogen in male budgie body.
ESSC tumor makes a male budgie’s cere brownish by doing budgie’s body estrogen dominant.
In addition, male budgies shows female-specific behaviors when under the influence of the disease.
Testosterone treatment on female budgies removes brown cere color
There is a study on female budgies shows how effective hormonal level effectiveness on cere color.
In the study, scientists gave testosterone hormone to female budgies for ten weeks.
After the first four weeks of testosterone injection period, cere colors had begun to change.
Cere colors of testosterone injected female budgies began to change brown to blue.
Ten weeks of testosterone injections into female budgies changed the color of their cere significantly from brown to blue. However, the female budgies did not show enough masculinity to admit that the overall process was a sex change.
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