There were a large number of frogs at the marsh where I studied Caltha palustris while visiting QUBS. I managed to snatch this rather good shot of L. pipiens while there.
Yesterday evening E. and I went for a walk and ended up at a small park with a pond near the southern edge of the Glebe, where we saw a heron hunting in the reeds. It appeared to be quite efficient at catching minnows.
Just outside the park I caught a Bufo americanus (American toad, family Bufonidae) which was jumping in the road and returned it to the park. Of course, it peed on me for my trouble, which they tend to do when they're picked up. They also release some fairly noxious things from special glands when handled which can be harmful if you get it in your eyes or ingest it, so wash your hands after handling toads. (Note: they don't give you warts, that's a myth).
Both families (Ranidae, Bufonidae), among others, lay their eggs in water, where they hatch and live for a portion of the life cycle as tailed, limbless tadpoles. They then gradually develop their limbs and lose the tail and become mature adults.