Two years ago I put in a natural swimming pool (no chlorine or chemicals, the water is filtered through plant uptake of nuturients, a filter media, and ultraviolet light). Almost immediately we had quite a collection of small frogs, which is understandable since we live on a 5 acre wooded site and peepers, tree frogs, cricket frogs, etc. are naturally abundant.
We now have two resident bullfrogs. Not only have I heard them, but I’ve seen them both (they’re hard to miss). Where did they come from? The nearest body of water is a sizeable pond about .5 miles from my house. There’s a stream several hundred yards from my house, but is only intermittent and not perennial. Absent spontaneous generation, did these bullfrogs migrate from the other pond? How did they find mine? The sound of running water? Google map?