All frogs gone?

I had a period in which there were no frogs - I assumed it was because it was winter, but no. I swear the game knew I needed frogs and was giving me those flipping time capsules to spite me. Later, when I no longer needed frogs, they were everywhere, no matter what the season.

Someone mentioned Newcrest - in one of the lots near the pond, there is a reliable frog-spawing site. There are also three frog-spawning sites near the fishing locations (not the pond) in Newcrest.