Thursday 16 May 2024

The Pool Frogs of Greenham Common 15th May 2024

Today, one that promised warm sun, I went to Greenham Common Nature Reserve in the neighbouring county of Berkshire.

In  the dark days of winter past, a chance conversation with a fellow birder alerted me to the fact that it was possible to see  Pool Frogs in a pond at Greenham Common during the months of May and June. I stored this information at the back of my mind until today when I decided to put it to the test.

The pond in question, fairly near the car park is situated away from the main paths in a quiet, neglected corner which is probably just as well as this large reserve can get very busy. Signs tell dog owners, of which there are no shortage, to not allow their dogs to run amok in the pond as.there are other ponds where they can let their dog do its worst if they so wish. By and large the dog owners that come here adhere to the request and if not there are volunteer rangers to ensure they do.

Consequently the pond's habitat has not been trashed, the water is clear and undisturbed and water lilies prosper in one corner whilst the margins are suitably populated with weed and reeds in which the frogs can hide and live out their lives.

I arrived at around 8am which was far too early and for the next hour and a half there was neither sight nor sound of any frog whatsoever. For a thirty minute diversion I walked over to some distant bushes where a Nightingale was singing loudly and even managed a brief glimpse of its russet coloured body as it sang from deep within a hawthorn thicket.

I returned to the pond more in hope than expectation and as I feared there was  still no sign of any frogs. I had arranged to meet Peter here at 9.30am and was about to concede defeat when simultaneously Peter arrived and I heard the first frog's croak emanating from the far side of the pond .It was 9.30am! 

Pool Frogs breed later than our Common Frogs which commence in March and April whereas the Pool Frogs choose to breed in May and June.As with our Common Frogs the croaking comes from the male Pool Frogs which inflate a sac on each side of their throat to create the sound which is surprisingly loud.

The sun was  beginning to warm the shallow water and in turn the frogs, which like to come to the surface to bask in the sun, commenced becoming more active
However the first tentative croaks soon fell silent as one of the frog's deadliest predators, a Grass Snake, its cold blood also warmed and energised by the sun, swam round the margin of the pond, eventually passing by almost at our feet. Its head was held above the water as its black forked tongue tasted the air. With sinuous grace its long body waved in curves under the water, propelling it forward. I was granted an expressionless pitiless stare from a golden yellow eye and then it was gone into the aquatic vegetation at the margin of the pond. Doubtless a luckless  frog would become its victim.

I have to confess to an uneasy relationship with snakes.On the one hand I feel an instinctive revulsion and fear but on the other a fascination and attraction I cannot rationally account for.

With the snake's departure the frogs croaking recommenced although remaining intermittent as slowly more and more frogs revealed themselves.Never having been to the pond before it took me a little while to familiarise myself with the frog's routine. There were definitely areas of the pond they preferred, close in to the margins where they would lie in the weed at the surface. They were ultra cautious and one had to move very slowly and carefully otherwise they would crash dive below the surface with an audible plop.

Standing quietly in a particularly favoured sunny corner with lots of weed by some overhanging bushes, brought the best results and provided I remained motionless more and more frogs surfaced there.

Pool Frogs are similar in size to Common Frogs but if examined closely can be told by their more pointed heads and longer legs. 

The males were in the majority, the larger females much fewer. All were predominantly brown or green in colour, overlain with darker blotches, bars and spots, the markings varying greatly from frog to frog. 

One large individual, possibly a female was intriguingly and attractively spotted all over its body, while others showed varying degrees of green on head and body and all a prominent light yellow or green dorsal stripe running down the entire length of head and back. 

ool Frogs were, until relatively recently, shrouded in confusion as to whether they were truly native to Britain. There would appear to be two separate populations, the Northern Pool Frog, very much range restricted and endangered, found in Sweden, Finland, Norway and Estonia; the other, the Southern Pool Frog much more widespread, occurring across a large region of central, southern and eastern Europe into Russia

It has been established that the Northern Pool Frog was indeed native to Britain with bones being discovered that dated from mid Saxon times and there are records documenting their presence in England well before any known frog introductions. Unfortunately just as it was determined they were the rarest  of our native amphibians the last known colony at Thompson Common in Norfolk became extinct in 1995!

However in 2000 Northern Pool Frogs from Sweden were re-introduced to two sites in Norfolk, one undisclosed, the other being Thompson Common, their last known location in Britain

This would suggest that the Pool Frogs at Greenham Common are of the southern form and therefore not native and must have been introduced at some point.Not that the frogs care about such semantics,

Whatever the provenance it is nice to see them apparently thriving in their undisturbed pond, a welcome addition to Britain's impoverished biodiversity and bringing much pleasure to those who know of and wish to see them.

So it was that approaching noon I put the camera down and stood, silent and contemplative in the warm sunshine by the peaceful pond with its raft of water lilies and shared some time in the presence of the frogs, staring inscrutably with goggle eyes as they sunned themselves amongst the tangles of weed.The Nightingale's sublime notes, although coming from afar, clearly audible.

Spring in all its glorious profusion, variety and wonder encapsulated right here. 

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