How do birds tell the time

[Thedoog]

Our resident Blue Tit and Great Tit have just gone in to there respective nestboxes as normal. The thought struck me how do they know the time, as they arrive at the same time every evening, but allowing 2 to 3 minutes for lighter evenings. Also they arrive together, do they spend the day together even though there not the same type of tit.
All we want now is for both of them to find mates and raise a family in our boxes.

 

[Gagakev]

Time flies when your having fun,

Sorry Steve could'nt resist that one.

 

[OmOnWeelz]

My birds got a Seiko and a Omega for day wear and a Rolex but she mainly uses her mobile for time keeping, alarm calls and diary

 

[Lord Braykewynde]

Our resident Blue Tit and Great Tit have just gone in to there respective nestboxes as normal.

Obviously their parents didn't tell them the facts of life. One big tit and one little tit don't make a matching pair

 

[brightmore]

They've obviously got a cuckoo clock