Which preposition to use with wagtail

on Occurrences 2%

How could I dream that these white shoulders, this breast covered with violets, this pretty face with the dark eyes, in short, this girl in the full bloom of maidenhood, was the same as the little wagtail on thin feet I had known formerly.

at Occurrences 1%

'She looked on Krishna who desired only her, on him who for long wanted dalliance, Whose face with his pleasure was overwhelmed and who was possessed with Desire, Who engendered passion with his face made lovely through tremblings of glancing eyes, Like a pond in autumn with a pair of wagtails at play in a fullblown lotus.

Which preposition to use with  wagtail