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Green frogs in Östergötland

PostPosted: Sun Jun 12, 2016 2:01 pm
by Jan Pröjts
In Sweden you can find edible frogs Pelophylax kl esculentus in the southern county Skåne, where this hybrid lives separate in good numbers as diploid and triploid frogs. North of Stockholm in Uppland we find the pool frogs Pelophylax lessonae, well separated geographically from other Swedish green frogs. Some of those northern pool frogs were exported to England in 2005.

The 700 km area in between Skåne and Uppland there were earlier a few old localities fairly close to the Baltic coast. The last remaining natural population in this area is located at Hannäs in Östergötland county at 58 09 N, a place which I visited last week. In the forest pond Lindalsgölen above the village you can still find at least 50 adult frogs today. Although this small population was discovered as late as 2004, green frogs of an undefined sort had been observered in the nearby lake Vindommen since 1975. The Lindalsgölen frogs were genetically examined in 2004 by two Swiss scientists which concluded that the population was a lessonae/esculentus system, a former unknown system in Sweden.

Today the frogs are most easily observed in the pond in June, when the males are croaking. But I was also lucky to find a female in a new pond near the lake, where the frogs lives much more undetected.




Re: Green frogs in Östergötland

PostPosted: Sun Jun 12, 2016 4:15 pm
by Mario Schweiger
nice pictures, Jan.
With these large parts of yellow, they look like lessonae

Re: Green frogs in Östergötland

PostPosted: Sun Jun 12, 2016 6:14 pm
by Jan Pröjts
Other pics of males, egg clutches and breeding habitat at the side of the pond. Water temperature was very high in the evening (28,3 C) but pH low and on the edge of what the species can tolerate (5,8-5,3).





Re: Green frogs in Östergötland

PostPosted: Sun Jun 17, 2018 10:33 am
by Jan Pröjts
Another green frog locality in the woods has been discovered last week 15 km S of the one at Hannäs. Future will show if the frogs are of the same lessonae/esculentus type.