Froglife (the wildlife charity for conservation of amphibians and reptiles) advise that frogspawn is not taken from one pond to another to help control the spread of invasive pond plants and amphibian disease.
Each female usually produces one clump of frog spawn in a season usually in warm days in March. Frog spawn is laid as lumps about the size of a tennis ball made up of jelly and eggs on shallow shelf areas and then as they mature these lumps swell to grapefruit size and beyond so that many can merge to look like one jelly mat.
Pond conservation are asking pond owners to take part in the Big Spawn Count to see how many lumps of spawn appear in your pond so they can see how many breeding females are reported.
Big Spawn 2012 count results: The average number of spawn clumps in garden ponds was twelve eqivalent to 12 breeding females visiting. It was quite common for people to report over 20 clumps, and nearly a fifth of people had this much spawn. Bigger ponds had more spawn, with an average of 28 clumps and the smallest garden ponds had an average of just over 6 clumps, with medium-sized ponds averaging 13 clumps.
The adult female lays several thousand eggs to allow for huge losses - each in a clump of jelly with dark brown-black centres but a clump of spawn will sit half submerged under the water and half exposed to the air and so vulnerable to being killed by overnight frosts. Dead eggs will have grey or white centres. In a light frost only the spawn closest to the surface will be killed the rest may survive as they are insulated from the cold in the centre of the clump. If a small amount of spawn has died leave it in the pond and it will break down or get eaten by other creatures but a large amount of decomposing spawn jelly can overload the pond with nutrients so take it out and put it on the compost heap.
Live tadpoles will live on the jelly that provided protection before they hatched out and will then survive on algae and vegetation in the pond. Once they start to develop legs, tadpoles change from being vegetarians to carnivors. Most established ponds will have enough food for the tadpoles to develop to maturity.
|Many tadpoles are eaten in Spring - up to 90% of the eggs, tadpoles or froglets in the pond are lost to predators (dragonfly larva, water boatmen, snakes or birds as they swim in the warm shallow waters at the edge of a pond. They need as much cover from plant leaf as possible so they have somewhere to hide from these predators. This would include Myosotis species, Veronica beccabunga and in a larger pond area - Mentha aquatica, Menyanthes trifoliata and Rorippa nasturtium-aquaticum.
Garden ponds are often home to more than one species of amphibian - see newt and toad sections - this is a healthy situation and shows that the pond is functioning well. A cyclical predator-prey relationship will establish where the numbers of one will control another until all becomes balanced eg newts are a predator of frog tadpoles especially in the weeks immediately after frog spawning when adult newts are in the pond laying their eggs on the same pond plants the tadpoles are swimming in.
Adult frogs can be affected by Frog red leg - ranavirus - on hot days between , as it is most virulent at temperatures above 25°C. rogs may appear with:
Abnormal wasting (emaciation).
Redness of the skin (erythema).
Skin ulcers or sores.
Bleeding (systemic haemorrhaging), especially from mouth/anus.
Breakdown of limbs (limb necrosis).