Wildlife-lovers may not think twice about handing over ‘excess’ frogspawn from their urban ponds to other gardeners to give frogs a new home.
But today conservationists urged home-owners not to indulge in ‘spawn-swapping’ this spring because of the harmful diseases and invasive plants that can hitch a ride with the eggs.
Froglife said that instead of moving frogspawn around artificially, gardeners should make their gardens attractive and accessible to frogs to encourage natural movement of amphibians and other animals.
If the common frog – which is widespread in the UK – moves of its own accord, diseases are likely to spread more slowly and less widely, while non-native plants will not take hold and threaten ecosystems in new habitats, Froglife said.
The charity said wildlife-lovers should not worry that there is too much frogspawn in their ponds, because frogs lay thousands of eggs on the basis that only the strongest handful will survive to breed.
The large number of eggs, up to 3,000 in each cluster, laid in the current breeding peak can provide food for other wildlife such as dragonfly larvae and newts.
The charity also warned that selling frogspawn, tadpoles or frogs in the UK is illegal, and it monitors eBay each spring to check no one is breaking the law.
According to Froglife, research suggests frogspawn can carry a disease from their parents called ranavirus, which is relatively new to the UK and has killed thousands of frogs each year since emerging in the South East in the late 1980s.
A number of harmful plants can also be transferred in the water with frogspawn, including parrot’s feather, water fern and floating pennywort, invasive species which have become established in the wild in recent decades with the growth in the international trade in pond animals and plants.
Froglife said Australian swamp stonecrop, an aquatic plant which forms dense ‘carpets’ and cuts out sunlight to other plants, was of particular concern.
The government has proposed adding all four species to its list of invasive plants and animals which people are forbidden to release into the wild.
Daniel Piec, head of conservation at Froglife, said: ‘Sadly, moving frogspawn around often serves only to heighten the risk of moving around invasive plants and diseases that have potential to do real harm to frogs and other pond-inhabitants.
‘If you want to do the best for our wildlife, our advice is to leave frogspawn where it is and let nature do the rest.’
Froglife is suggesting a series of frog-friendly measures which enable the common frog to move naturally to new ponds.
They include avoiding concrete-based fencing round gardens, and adding log piles to attract food and rockeries to provide hiding places for the frogs.
Froglife’s Lucy Benyon said: ‘Making gardens ‘frog-friendly’ in this way allows other native species a way into ponds too – whether it’s newts, pond-skaters or grass snakes – and these gardens form wildlife corridors that naturally encourage the movement of animals between ponds.
‘This gets rid of the need to artificially introduce spawn and lessens the risk of invasive species and diseases spreading further via accidental introduction.’
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