Wildlife Spotting

Every year we find tadpoles in an area of standing water within a field at Cox Reservation in Essex, MA. We raise them and then release them when the first few have their tails and arms and lost their tails. We always release them to the same place. This year, the standing water has dried up, and we are thinking we should release them somewhere else. I am wondering what kinds of habitats might work -- e.g. vernal pond, woodland creek, etc. It would help to know what species this is. Among the tadpoles, there are a couple of smaller ones that still don't have legs or arms. I wonder if they are just behind schedule (maybe they were born later) or if they are another species. We collected them all at the same time.

I also wonder at what point the frogs begin to eat insects. Up to now we have been feeding them pond weed and boiled romaine lettuce. In other years I have put insects into the tank but the tiny frogs/toads have shown no interest, as far as I could see. Any insights re. identification, the remaining tadpoles, and the frogs' diet would be much appreciated.

Are these maybe Fowler's Toads or American Toads? They climb up the sides of the glass tank, if that is another clue.