Hibernacula

I had not seen the turtles since the beginning of December, when I saw them mating in freezing water. Since then, the pond has frozen more than once, but I have not seen them. For me it is a mystery why sometimes the ice seems to activate them and others does not. One difference is that in the last freezing episodes, it was not too cold and the ice was very thin in the morning. Maybe it formed later and it melts sooner. Who knows what will happen next time the pond freezes properly, but I don't dare to say I will see them .

So, with or without ice, I had not seen them until today, when I have discovered where they are hiding. The stay under a cork bark,  at a depth of  30cm, near the roots of a cattail. Both turtles side by side, you can see it with a little imagination in the last picture. 

The cork bark only touches the water by one side, so it forms an air pocket. Although winter can freeze most of the pond, I don't think it happens in the water over the hibernacula, protected but a 4cm thick cork (and I neither think it happened the day they were moving under the ice, so, the passage of  air to the pond was not blocked!). I will check it in the future. I also remembered of a picture I saw in an internet text about this species

http://www.google.es/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&ved=0CDAQFjAA&url=http%3A%2F%2Fwww.bryoecol.mtu.edu%2Fchapters_2011%2F15Reptiles.pdf&ei=-_XJUIboJMPKhAe664CwDw&usg=AFQjCNHa58kQgPVSLFoMNaJ66sXVjwEaSA&sig2=5pUDODVivrRBf1sCXNeAHg&bvm=bv.1355272958,d.d2k