How does chicken knows the appropriate time at night?

A circadian rhythm is an endogenously driven roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria. The term circadian comes from the Latin circa, meaning "around", and diem or dies, meaning "day". Although circadian rhythms are endogenous ("built-in", self-sustained), they are adjusted (entrained) to the environment by external cues called zeitgebers, the primary one of which is daylight.

When you travel very fast..... say from here to America.....it will throw off your natural biological clock.... the common name is "jet lag"..... your body wants to sleep during the day and can not sleep at night.....until it re-adjusts (note you can help your body re-adjust quicker....but that is another subject for another time).....

If you transported a chicken from here to America..... it would be temporarily out of sync also

BTW there is a native bird that crows at 2 PM .....it uses the same biological clock

Is this another Chicken Joke ? hehehehe The Filipino chicken does not know , He crows all night ! Every five minutes.

Time is a human thing. Chickens know when it's dark & when it's light.

They don't. Call it some sort of body clock.

My grandpa woke up early everyday when still alive, he used to wake-up our roosters when it was time for them to crow.

in philippines, ancestors knew this. my grandparents told me that they have this ability since.

chicken has the oldest family of animals in the world and they have great rhythm with daily routine. roosters crow at 7pm, 10pm, 4am, 6am

right, and same with the toko, or the lizards

find it more in this site:

http://www.geotravephilippines.com/

They look at the clock or answer other roosters when they crow

You don't know.

Most of them has their alarm clock under their wings, they set things so that they can crow when time comes.

i don't know ,i haven't talked to any chickens lately

god give them the knowledge of what is dawn and what is dark .