This pair of mallards are what constitutes megafauna in my parents wildlife pond. The wildlife pond sits next to a much larger koi pond - since the koi pond is deep, weed free and steep sided it is a bit of a wildlife desert but it does sometimes attract waterfowl who then realise the smaller pond is more suitable for them.
This pond is only 2 years old. When we set it up we moved the entire contents of a much smaller pond from elsewhere in the garden into it (plants, snails, larvae, water you name it). We had always had frogs and newts in the little pond but never frogspawn and very few newt tadpoles. Since we set up the new pond we've had an amphibian explosion. I wouldn't be surprised if the mallards were eating some of the enormous clump of frogspawn (seriously its like the size of a dustbin (or trashcan for american readers) - I mean how many frogs does it take to produce something like that?). I only have one photo as they're pretty skittish.
I first realised this pair were using the pond when I went spotlighting to check the newt population at night and woke them up giving both of us a scare in the dark. Hopefully they'll stick around to nest and we'll have ducklings ambling from pond to pond.
Last year we had up to 8 moorhens wandering around at a time but there don't seem to be any this year. We think they've either returned to a reedier local lake for nesting purposes but will be pleased to see them return as they are supposedly a good indicator that wildlife devastating feral american mink are not in the area. Where we are grey herons almost always show up at ponds and kingfishers are not an unreasonable expectation either.
Anyway - all the books recommend a pond is agreat way to attract birds to your garden and then show something smaller bathing in it - I thought I'd write this post to share some of the more impressive-sized and easily watched birds that can be attracted to a garden by a small pond.