Hi Richard
Unfortunately yes they do eat frog spawn, my old call duck was a devil for it. They can also pollute a pond so much everything dies. I got around it with a pump and a big pond. campbells, like runners can manage with an old trough of water, they have to be able to get their eyes wet and be able to get out.
My ducks died of old age, my call ducks Jemima and Mr Drake died last summer aged 10 and 11. Oddly I cried for days when they died (an odd confession for someone like me I know) but they were little characters. I am getting some more white campbells hopefull next week though so I am very excited! Our old runners were called "Sita" and "Rama" which my daughter named, they live until they were four and five.
I hope that you do hear the patter of tiny webbed feet, there is nothing quite so cute! OOh and the eggs make brilliant sponge cakes if you are into that sort of thing. I also won the village fete with my lemon curd made from duck eggs, the first time entering, it put a few noses out of joint I can tell you!
Rosey