Do Toads/Frogs see young as "Lunch"?..

I've not witnessed intraspecific predation (great term for eating each other eh??) in Rana temporaria directly, but I have seen anecdotal evidence of it.

I moved approximately 250 common frogs from an enclosed courtyard in London a few years ago. I was told that large amounts of spawn had been laid both that spring and also the following year and many tadpoles had hatched and grown to a good size.

However there were no small frogs, not one. The smallest were approximately 2.5 inches snout to vent. So, I would guess that the entire two previous years cohorts were missing entirely. Add to this that I saw no evidence of terrestrial inverts in the courtyard during extensive destructive searching, and I concluded the only food source for any of the frogs was smaller frogs. Interestingly the largest specimens were all malnourished. So I guess there is an optimum size for preying on your own species when youÆre a common frog  

A caveat to this is that there may have been other explanations for why the previous two years offspring perished, but it wouldn't explain what the medium sized frogs had been thriving on.

In all I would say adults common frogs will not differentiate their young from any other moving mouth sized morsel, but if plenty of other food is available it will not happen that often, else I doubt they would still be here. I know many species rely on various dispersal tactics to avoid intraspecific predation of their own young.

Marsh frogs certainly eat other smaller frogs also.