There can be very few of us who did not watch common frog (Rana temporaria) spawn turn in to small frogs in our school days. It was many years ago now but I remember quite clearly a fish tank in the corner of our classroom at primary school with developing frogs in it. We watched as the spawn hatched in to tadpoles and then as the tadpoles grew legs and developed towards being mature frogs. One day the tank was gone! Our teacher had decided that they were close enough to being adults that they needed to leave home ...
Towards the middle of February each year significant numbers of frogs, possibly sixty or seventy, make their way in to our garden pond and for a couple of days there is a complete frenzy of mating frogs and then silence, they are gone. Left behind are the sticky masses of spawn, lumps of small jelly balls with a black dot in the centre of each. The spawn is so vulnerable to freezing weather and in some years is lost. Then the blackbirds take their share too as the spring progresses and they have young to feed.
Despite this predation and the vagaries of the British weather there is so much spawn and so many tadpoles that many will survive and leave the pond in June to live the rest of their lives on land returning to our pond next spring to ensure the cycle continues. Once adults they will live much of their lives out of water and are more active at night when its cooler but in hot weather you can see them by day back in the pond of their birth to keep cool and moist.
All frog species have smooth skin which easily sets them apart from the simlar toads which have warty skins. The common frog generally has a blotched olive green skin but it can be quite variable.