The turtles and the ice

The temperatures have dropped quite a lot since last week, specially the nocturnal ones. Although they have not finally been historical, it has been cold enough to keep the pond frozen all those days. 

It snowed again last weekend, and the ice was covered by the snow.

The aerator is proving very useful. It oxygenates de water, but it also keeps a window open in the ice. In a frozen pond, the oxygen of the air does not pass to the water. The window created by the aerator allows some contact between water and air, and it also provides the turtles the possibility to  breath air.

The birds take advantage of  the window in the ice now that it is so difficult to find liquid water 

Yesterday morning, at 9:22, with an air temperature of -4ºC , I saw the turtles under the ice. At the end of the month, the probe will tell the water temperature in that moment. I was surprised to find them at that time with that air temperature. It had not happened in other winter days, with warmer temperatures. I did not think it was an emergency situation. A frozen pond is not extraordinary for this turtle species, they have strategies to survive with very little oxygen, and possibly can survive for some weeks without oxygen (I previously talked about it and put some article links). There was also the window created by the aerator. But I thought it was curious that of all the winter days, I found them active precisely now, when the pond had been frozen for a week, so early in the morning with such low temperatures for an ectoderm. Could it be that, although they have physiological mechanisms to cope with the lack of breathing air, they try first the easiest solution? (find a window in the ice)

It is probably the female, this is close to the place she chose to hibernate. You can see her left forearm. She is facing the window in the ice.

This midday I have seen them again. The air temperature was 7ºC , but it was sunny and you could feel the sun's heat. One of the turtles stayed among the algae, in the thawed area near the aerator. The other one was moving slowly under the ice. It stayed there for about 10 minutes, then moved near the aerator and, without breathing air, she swam to the deeper water, again under the ice. If they had wanted to take air at some point, they could have done it (in fact they had many other moments of the day to do so, when I wasn't there to see it)

The dark shadow is the turtle. You can even see the yellow spots, specially on the head.

Ready to swim towards the deeper area

In the weather forecast they said the cold days will still last  for some days. The pond will remain frozen some days more.