What animal am I ?

What animal am I ? I have a beak and two webbed feet Eating snails is quite a treat On land I waddle In the bath I bobble But two things I do really well What am I, can you already tell ? My wings flap flap as I fly in the air My feet flip flip in the water when I'm there If you get too close I may peck and hiss Swimming on the lake eating worms is bliss Give me a crust of bread and then stand back I'll thank you with a big quack quack