Flamingos in captivity are often just a pale shadow of the more vividly colored wild flamingos.
These standing on one leg* live at Jerusalem's Biblical Zoo.
The zoo website explains:
"The flamingo feeds mostly on pink shrimp and blue algae, which hold the beta-carotene pigment--giving the bird its unique color. In zoos, flamingos are given food with a color additive or vegetables like beets, red peppers and carrots to maintain the pink color. The birds' color is mostly important for courtship rituals."
* The famous story from the Talmud (Shabbat 31a):
Rabbi Hillel, when asked by a prospective convert to Judaism to teach him the whole Torah while he stood on one leg, replied:
"That which is hateful unto you do not do to your neighbor. This is the whole of the Torah. The rest is commentary. Go forth and study.".