# How Do Wild Birds Sense Time?

**URL:** <https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393>\
**Category:** Factual Questions\
**Created:** [April 8, 2010, 9:53am UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393 "2010-04-08T09:53:28Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\
**Post date:** [April 8, 2010, 9:53am UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/1 "2010-04-08T09:53:28Z")

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Here in NE, Spring has come, and along with it, the wild songbirds. They are a welcome relief from the silence of winter, but how do they know when to start their racket?  
Here, they seem to start calling about 1 hour before sunrise-and call it quits just about at sunrise.  
How do they sense the time?

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**Author:** ![ivan\_astikov](https://avatars.discourse-cdn.com/v4/letter/i/58f4c7/32.png) [@ivan\_astikov](https://boards.straightdope.com/u/ivan_astikov)\
**Post date:** [April 8, 2010, 9:56am UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/2 "2010-04-08T09:56:56Z")

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When it starts getting light, and when it starts going dark. Mystery solved.

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**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\
**Post date:** [April 8, 2010, 1:10pm UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/3 "2010-04-08T13:10:16Z")

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Yeah, if for some reason there’s a false dawn, or a lot of human-generated light that they’re not used to, they will also wake up and begin chirping.

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**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\
**Post date:** [April 8, 2010, 1:28pm UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/4 "2010-04-08T13:28:25Z")

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“Twilight” mean both dawn and dusk – there is a period of lightening before sunrise as well as a period of decreasing light after sundown. Birds tend to sing at twilight.

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**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\
**Post date:** [April 8, 2010, 2:16pm UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/5 "2010-04-08T14:16:13Z")

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Like most organisms, birds have endogenous circadian rhythms. That is, they have an internal “clock” that will tell them the approximate time of day regardless of any external clues.

This said, most early morning bird song tends to start at “first light,” the first perceptible light in the morning sky, which they can detect. Similarly, they know what time it is in the late afternoon by the position of the sun in the sky and declining light levels.

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**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\
**Post date:** [April 8, 2010, 2:24pm UTC](https://boards.straightdope.com/t/how-do-wild-birds-sense-time/535393/6 "2010-04-08T14:24:32Z")

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Well, _something_ told the wild geese it was time to go!