It seems the English grammarians are yet to settle on a collective noun for robins, with options ranging from ‘a riot of robins’ to ‘a bobbin of robins’. The most apt seems to be ‘a carol of robins’, but you might prefer, ‘a red of robins’ or, ‘a hood of robins’!

Watercolour illustration of Three Robins with cherry Blossom by Daniel Mackie. Printed on High quality 330gsm card. Cards are 7 x 5 inches.