The hatchling hibernating

Yesterday I checked the hatchling that is now hibernating. It is in a bucket with little water in a well ventilated shed.  It is a cold place but protected from freezing. I put a plant and some roots that the turtle uses as a hiding place. By simply extending the neck it reaches the surface. Apparently all goes well.

December temperatures

Some time ago I talked about the data loggers that I put in the pond at 10 and 50 cm depth. They measure the temperature with a pre-programmed frequency, in this case every hour. The last day of each month I download the data. These graphics correspond to December (warmer than usual, as it happened in November)

Temperature at 10 cm depth

Temperature at 50 cm depth

November and December air temperatures, 10 cm above the ground.

Some days I found the pond partially frozen (all but the area nearer to the bubbler). The temperatures of those days at 9:00 were

19-11-12  Air -1,7ºC, at 10cm 3,09ºC, at 50cm 4,09ºC
20-11-12  Air -0,69ºC, at 10cm 2.6ºC, at 50cm 3.59ºC
28-11-12  Air -0,56ºC, at 10cm 3.59ºC, at 50cm 4.09ºC

The water was colder at 10cm. than 50cm. This is because the water temperature was lower than 4ºC. As the water cools down it becomes denser (and heavier). Thus, in the summer, the water is cooler in the bottom of the pond. This is also true for the winter... until the water temperature is lower than 4ºC. Then its density, instead of increasing, decreases. Being less dense this water occupies a  higher layer (if it was not like that, the pond would start freezing in the bottom)

Regarding the turtles, I have seen them active several days in December. Always at midday on sunny days:

04-12-2011 at 12:00. Air 7.53ºC, at 10cm 8.9ºC, a 50cm 7.6ºC. The female didn't leave the water but stayed between the vegetation with the head out of the water for several minutes.

06-12-2011 at 14:00. Air 9.04ºC, a 10cm 8.09ºC, at 50cm 6.6ºC. The male was sunbathing in the land area.

08-12-2011 at 15:37




Air temperature 9.79ºC. Water at 10cm 7.1ºC, water at  50cm 6.6ºC.

27-12-2011 at 14:00

Air temperature (in the shadow) 9.92ºC. Water temperature at 10cm 5.1ºC, water temperature at 50cm 4.58ºC. The male stayed sunbathing for an hour in the land area.

In these cases the water temperature was higher than  4ºC  and the water in the bottom was colder than in the surface. 

I haven't seen the turtles since December the 27th, when I took that picture, although the weather has not been cold nor cloudy.