Where I used to live we were over run with frogs even found a couple in the house they had hopped in one summer afternoon while we had the back door open, same as you we never had a pond and none of our neighbours did but aparently before the houses were built it was a massive big field with a big swampy pond in it and even though that had gone the frogs hadn't! Can't understand why they stayed and not even sure where the nearest pond was!We find frogs in our garden. Now that's not very strange as I have a very nice greeny, critter friendly garden. However we don't have a pond and none of my neighbours either side or over the back do either.