Nice!

Somehow I doubt we'll have the pleasure of blue frogs up here this year. Though arvalis are quite common, not being much of a frog guy I never paid them much attention. I've seen the blue ones - by chance - a couple of times but don't have any pictures.

I saw the first arvalis of the year - one specimen - at the edge of a pond still nearly completely covered by ice yesterday. After getting home I consulted the litterature to see when I might expect to find them breeding. To my surprise I read that the males don't always turn blue during mating season. Apparently it doesn't happen if the water is too cold and given the conditions here this year, well... 

Where did you read that, Kristian?

Nice one, Mario! 

You are right, Kristian!
@ Jeroen: I dont know, if this is written anywhere!

If the water is to cold, the males only get a bluish shine and dont turn to this bright blue. Also they show this blue only during sunshine. When watching, you have to move very very slowly, not to frighten them (but you may talk with your companions as loud as you would like). If the frogs dive away, it needs up to 2 hours, before they change to bright blue again.

Mario 

& Jeroen,

in "the pocket Bible" with regards to the herpetofauna of Scandinavia: Fogh, Schmedes & Rosenørn de Lasson: "Nordens padder og krybdyr", Gad, 1996.

It also states that some populations, including all the northernmost ones, never turn blue. 

Now the video is online!

1) small and high compressed (368 x 208 px, 12.6 MB)
http://www.fieldherping.eu/video/RanaArvalisWMV.wmv

2) fullHD - DivX compressed; you will need DivX codec to watch. This HD video is 115 MB!!
http://www.fieldherping.eu/video/RanaArvalis2.divx

Duration 5:03 minutes. The video shows Rana arvalis swimming around, portraits of different marked individuals, some males brawling for 1 female, egg laying, aso.

Mario
 

Awesome shoot !! (your HD link doesn't work..) 

Thanks, M. The frog porn bit (fertilisation) is interesting.

For Belgian arvalis, your statements about sunshine and loss of colour when spooked are not valid, although they do lose colour when you hold them.

Funny is that your frogs sound a bit different than ours, which are more like this =>
www.youtube.com/watch?v=l0fSAkBRP8g

BTW, please note that wolterstorffi is invalid.
http://www.eko.uj.edu.pl/molecol/publikacje/11.pdf 

The apparent regional differences in regards to color change are interesting. In the book I referred to earlier it is also stated that they loose the blue colour when spooked. 

Sorry, I typed *.dixv instead of *.divx.
I changed it - now it works!

Mario