camourflage

[kronecker]

i am taking a course "human bebings and nature" (i don't know how to translate more corectly). we watch a video tape today about polar birds. i think it is an interesting documentary film. i am amazing at how their feathers color can change differently when different seasons come, 4 seasons 4 diferernt colors. i wonder what gives them abilities to change them like that, generation to generation.
thank you

[Moonbear]

Seasonal changes in coat (or feather) color are usually determined by hormone status, especially prolactin. Most people know about prolactin as a hormone involved in milk production, but it also has other functions. One of those is for fur growth and to provide the signal of when to switch from summer to winter coats.