Ancient time bird
From Tardis Wiki, the free Doctor Who reference
An ancient time bird was a bird that could alter time on a massive scale. One found itself in an underground tube station, trapping Ryan Goodman and the Eleventh Doctor fifty years in Ryan's future.
They managed to save it by making it go into the TARDIS, and restored time back to normal. (PROSE: The Fifty-Year Delay).
Description
Before he could answer, Ryan watched as a huge brightly coloured bird flew out of the tunnel. It shimmered and looked as if it was on fire. The creature seemed to fade in and out of existence as it looped over their heads and up and down the tracks. It was beautiful.