Many of our British amphibians are declining in numbers, and by aiding their survival in your garden or school, you will increase the numbers in your general area.  

Frogs will return to breed, if possible, to the site of their own youth.  Their masses of jelly-like eggs were once a familiar site in ponds, ditches and slow-moving water.  However, in recent years the use of pest and weed control chemicals have taken their toll, as they have on most of our smaller creatures - either by direct contact, or by reduction of the insects on which they live.   Drier summers and the reclamation of marshy land for building, industry or agriculture have also caused a reduction in the numbers of water dwelling creatures.  Many ditches and ponds have disappeared, or now dry up during the  summer months.  

Frogs are smooth skinned, and variable in colour.  They will change colour slightly to match their surroundings.  The webbing on their feet does not extend to their toes.  Frogs will hop on land, and swim in a series of strong, if ungainly, movements, using their powerful back legs to propel their body.  They will spend time around the pond or in the water during very warm weather, and can often be found at the base of water plants during sunny days.

Even at the best of times, only a small proportion of spawn will survive to develop to maturity.  Spawn and tadpoles will be eaten by a whole host of other water creatures - and frogs are not always the smartest of parents!  I have two adjacent ponds - one full of plants and no fish, the other full of large fish and no plants.  However stupid it might sound, the frogs usually choose the fish's side of the fence, providing a snack that will disappear within a few minutes if it isn't removed.  The chances of spawn or tadpoles surviving in a pond with large, hungry fish is slim, and it needs to be moved or protected as soon as possible.  Late frosts are also a source of danger - spawn often floats or lies in shallow water, and a hard frost will destroy the uppermost, or all of it.  Protect it in the best way you are able, according to it's position and the harshness of weather - an upturned bowl might be suitable cover against an overnight frost.  Last year a few days of warm but early sunshine caused early spawning, but they were followed by a week of sleet, frost and snow!  Unless the spawn was low in the water or in a sheltered area, it's only real chance of survival was to be transferred to a container of mature pond water that could be kept in a cold but frost-free place for those few days.  Avoid too much temperature change if you feel that you must take this course of action, and replace the spawn carefully when fear of frost has passed.  

Cold weather will slow the development of the spawn or tadpoles, but once free-swimming, tadpoles will dive to warmer water if the surface freezes, and come to no harm.  When the tadpoles hatch, they cling to the jelly mass for two or three days, possibly feeding upon some of it, until their strength develops.  At this time they are very vulnerable, lacking both stamina and protection.  When their feathery gills develop fully, and they have gained sufficient weight and size to swim and feed freely, they will seek plant and algae growth to provide food, warmth and a natural hiding place.  Slow, ungainly, and again, not altogether quick witted, they are still easy prey for carnivorous wildlife and fish.  

It is obvious that to move spawn to a fish-free pond or area of their own can be of great help to them, but bringing them in to the house - tempting if it's snowing outside - is not the answer.  Do remember these important things before interfering with nature:

1.  The tadpoles need algae, infusoria and plant material (often dead leaves) on which to feed.  They must be put into water that has had time to mature and provide plenty of food - they are vivacious eaters with a lot of growing to do!  Supplements of dried algae or seaweed wafers are greedily accepted.

2.  Although the swimming tadpole is a vegetarian, the day that it turns into a frog it becomes a meat-eater - and even best steak won't tempt it to eat dead meat.  If you bring them in to the warmth they will develop faster than nature intended, which means that they might become tiny frogs too early in the year for insects to be readily available.  Leaving them outside will ensure that they develop in time with the rest of nature.  Incidentally, sometimes slow developers will over-winter in tadpole form, not changing form until the following summer, when insect life is again plentiful.

3.   The frog can swim, but it breathes air and lives in cool, damp conditions for much of it's life after metamorphosis.  It is therefore essential that it can leave the water!  This 

might sound obvious, but the new frog is tiny - often no bigger than your smallest finger nail - and weak.  It cannot hop from water.  It cannot crawl up steep slopes.  It is imperative that there is easy access to dry land and cover around the water's edge.  Birds will naturally gather around ponds in the dry summer months.  Tiny frogs having to cross a paved patio - hot from the sun and giving no cover or shade - may easily suffer from damaged skin or fall prey to a bird.   Similarly, frogs will hibernate in the mud at the bottom of the pond, but if the water freezes over then they can quickly drown or be killed by the gasses that build up in the water.  Use a floating object or tiny heater to keep a patch of water unfrozen, just as you would for fish.

4.   The skin of frogs is thin and delicate.  If you must handle one, do so with cool, wet hands, again, just as you would a fish.

5.  As previously mentioned, frogs will return at maturity to the pond where they developed to breed, usually in their third spring.  If, for some reason, that pond is no longer there, many will fail to find an alternative in order to spawn.  If your pond is dry for some reason and you know that frogs might try to return to it,  try to provide them with an alternative until the original pond is refilled.  Prepare it in time to allow maturation of the water.

6.  Many of our wildlife species are protected by law and should not be moved - if in doubt, check with conservation societies in your area.  Tadpoles offered for sale by garden centres etc. are generally imported species, that might grow up to be a danger to our own native species, or be unable to withstand our winters.  Be sure of what you are buying!  If you intend to introduce native frogs from another pond, remember that they will want to return to their home pond to breed, and will object to an enforced change of abode.  Moving spawn is more sensible, BUT be aware that by moving spawn or tadpoles at any stage of their development, you risk moving disease from one pond to another, or even over-colonizing a pond.  Beware, in particular, of introducing stock from an area where the disease red-leg is suspected - it can wipe out a large colony of frogs in a very short space of time.

7.  Grown frogs will look after themselves, but their vulnerability!  They eat slugs -  so avoid using pellets, which will almost certainly kill any creature that eats a poisoned, dying slug.  Avoid also the use of weed-killers that will burn their delicate skin on contact.

In conclusion, I would say that frogs, though not top of the intelligence league - do seem to know when they are well off.  As your pond matures sufficiently to provide for their continued existence, and colonies of insects build up to provide the adults food, they will quite probably appear - apparently from nowhere - before the spawn that you might have acquired from elsewhere has developed into mature frogs.  By the same token, tadpoles that you bring from elsewhere will not thrive if conditions are not right for them in your pond or garden.  Adult frogs should only be moved if it is essential for their own safety. 

LIFE CYCLE OF FROGS

Click on the dancing frog to see life cycle photographs

Hundreds of eggs will be laid, stuck together in a jelly-like mass.  This will hatch in 5 - 10 days, depending on warmth, and the tadpoles will be free-swimming within two or three days.  The hind legs appear first, then the front.  The tadpoles are brown, and they become speckled as they grow in to a more shapely creature.  By the time the tail begins to rot shorter, the tadpole has assumed frog shape and colouring.  It will crawl onto dry land - maybe on water plants that are barely out of the water - and rest for a day, as the tail rots off completely and heals.  No bigger than a fingernail, the tiny frog may not return to the water for over two years - although I find that many young frogs are to be found at the base of marginal plants or among the lilies on a warm summer's day or evening.