Frogs and Frogspawn

Frogs have a special place in the hearts of most wildlife pond-keepers if only because they seem so very willing to reward our efforts by using our ponds so readily. Secretive outside the breeding season, frogs make a welcome addition to the garden – not least because they provide a highly effective slug control service, offering protection to the hostas and other tender plants in their adopted patch.

The Common Frog (Rana temporaria) is the most widespread kind throughout Europe – a remarkable survivor, which has increasingly made use of garden ponds as more and more of its natural wetland habitats disappear.

Froggy Goes A-Courting

Frogs usually emerge from hibernation at the beginning of March – though in some years they may put in an appearance even earlier – and spawning takes place from March through into April. At this time of year, these normally silent creatures become quite vocal, their underwater croaking frequently audible from some distance away and this can often be the first sign of their arrival in the pond. If large numbers of frogs are present, this sound has sometimes been likened to the rumble of a distant railway train.

Breeding involves the male grasping the female from behind, locking his forelegs around her body just beneath her armpits – an embrace known as “amplexus” – and he develops a special pad along his thumb to help him get a good grip on his girlfriend’s slippery skin. As she lays her eggs, he will fertilise them.

This instinctive need to find and grab a female sometimes leads to a few misunderstandings, as anything of about the right size may be grasped by a hopeful male – including goldfish and other males! While a female who is not ready to lay – or has already spawned – will bend away and kick at him and another male lets out a very distinct sound to tell our suitor the error of his ways, fish – unable to communicate with the amorous frog – may be grasped for some time before realisation dawns.

Female frogs lay their eggs quite quickly, producing perhaps 1,000 in an hour and laying around 3 – 4,000 in total. When newly laid, the eggs sink to the bottom but as the jelly covering them gradually swells with pond water, they float to the surface, where they remain often for two or three weeks until they hatch into tadpoles. Over the next three months, they develop from quarter-inch long “commas” hiding in weeds, then becoming carnivorous as first hind-legs and then fore-legs grow, before finally going through metamorphosis – changing into tail-less and perfectly formed miniature frogs. These small replicas of their parents then make their way onto land – a rainstorm often triggering large numbers to make the journey, which may well be the origin of the expression “raining frogs.”

Attracting Frogs to the Pond

The good news about frogs is that they are not particularly fussy and will happily use a wide variety of ponds, which makes them very easy to accommodate. The only real absolute necessity is that they will need a way to get out of the water – they can jump in, but an exit route is essential, particularly for the baby frogs. However, to provide them with the ultimate in desirable residences both inside and outside of the breeding season, the pond and its surroundings need to offer them somewhere to hide.

A well planted wildlife pond, especially with a bog garden attached will provide good refuge and building a rockery with lots of nooks and crannies, piling up some old logs or half-sinking old terracotta plant pots or pies beside the pond will meet their needs on dry land. It is also a good idea not to be too diligent when it comes to pruning. The plants growing around the pond’s edge often provide valuable cover to adults and young alike.

Although frogs tend to arrive all on their own, if you simply cannot wait, the quickest way to get the ball rolling is to introduce some frogspawn. Many wildlife ponds attract large numbers of breeding frogs – resulting in far more frogspawn than they can cope with, leaving their owners only to glad to find some of it a new home. If you do not know anyone with excess spawn, the local wildlife trust can often help suggest sources.

The last hundred years have seen the loss of something in the region of 70 per cent of Britain’s natural lakes and wetlands, but fortunately frogs in particular have been very quick to adapt to using garden ponds instead. While amphibian numbers around the world have been suffering significant decline in recent times, the frog seems to be a bit more of a success story – and long may that continue.