Reply to Es and sarahs pond life
Newts have a reputation for feeding on other tadpoles, but then they will all eat each other given the chance. A large pond, with enough variation in depth, marginal undulations and aquatic plants should be able to accommodate many different amphibian species. These vary year on year, so absence of frogs (and spawn) might be down to predation, or just a poor return from previous inhabitants.
I've just been out in the garden and there are four newts back in our pond. It is raised, made out of old railway sleepers, three high, so they have had to climb to get back in. Like frogs and toads they do return to the pools of their births, but because they are more shy and secretive, they are rarely seen in large numbers. Of course, some don't return to the ponds in which they were laid as spawn, they colonize new ponds, otherwise how would these new ponds ever get frogs, toads or newts in them. In the evolutionary time scale, ponds are transient short-lived water bodies (think ox-bow lakes) which may exist for years or decades, but eventually dry up or get invaded by willow, so amphibians must have some strategy for exploring for new spawning sites.
