Fourth week of incubation and second clutch

The egg seen from above

The same egg from side to side

Another egg seen from above

 The same egg from side to side

 

There has been a problem. I have to add water from time to time to the incubator. When I do it I switch off the heater. Last thursday I forgott to switch it on when I finished. This morning when I opened it the temperature was 20ºC instead of 30ºC but I don't think it affects the embryos. Two years ago I incubated one egg outdoors and it reached 12ºC and almost every night it reached the 20ºC.

 This summer is strange. Since the beginning of June we have afternoon thunderstoms every other day and temperatures are lower than usual, especially nocturnal ones. Today it is nearly a month since the Clemmys layed the first clutch. I palpated the eggs some weeks ago, but the female retained them until yesterday when we had a warmer day.

 

The female always nests in the same places, one in the west side of the pond, the other in the east side. She always changes from one to another among two consecutive clutches. It seems she somehow remembers where she layed the fisrt clutch and decides  to lay the second one in a distant place. Maybe it is a way to lower the chances of nest predation, or a way to avoid digging out the eggs of the first clucth laying the second one. It might also be a way to increase the chances of nest survival because of different microclimates in different places, which could also affect the sex of the hatchlings. 

For the second clutch she chose the west side. And there have been some problems. She began digging the nest yesterday evening (I saw her at 21:30). This morning, at 10:00, she was still digging in the same place.  12 hour making a nest and still not finished. 

According to David Carroll descriptions in his books, this turtle lays the eggs during the night to avoid the heat of the sun. A dark and small turtle can overheat easilly under the sun in land. About 10:00 the sun reached her
 

I doubted but finally  I picked her up to have a look. She dug a nest but there were no eggs. Could it be a dystocia? I left her in the same place again. When I came back a few minutes later I saw three eggs an no turtle. I saw her in the water section and I caught her. I palpated her and she was still carrying eggs. I put her in a bucket without water. While I was picking up the eggs my son told me the turtle was laying a fourth egg. It would have surelly been layed in the water if I had left the turtle in the pond. I palpated her again and this time I didn't feel eggs. 

Once I picked up the eggs I examined the nest chamber. It was very shallow. The earth was very hard.  When I disturbed her she just expelled the eggs and went to the water section carrying an egg that she would expell in less than two minutes.

A curious thing: the fourth egg has a shallow depression on the shell. I had seen this before

I had seen it in Terrapene carolina triunguis , in oxytocine induced clutches.

One possible explanation is pressure between the eggs in the coelomic cavity.

 

But if this was the explanation I think I would see it in the radiography, at least in some eggs. And it appears in all the eggs and exactly in the same place, dorsal as the eggs are layed. You can see it in the next pictures. If these were due to contact areas between the eggs, they  would show it in diferent locations, not all exactly in the same place.

 

I even thought if it could be some deformation of the passage of the eggs that caused it, but I discarded it when it happened with other terrapene. Always the same dent, the same size and exactly in the same place in freshly layed eggs. It dissapears during incubation.

I told about it to an expert chelonian keeper and his answer was quite logical: these are soft-shelled eggs. When they are being layed they collapse a little bit and a dent appears. Once incubation starts and the egg resorbs water the inner pressure increases and the dent dissappears.

Regarding Clemmys, also with solf-shelled eggs, I had never seen it in previous clutches. And only in one egg of today's clutch. The only difference with previous clutches is that they have been retained more than usual and that the eggs have been picked up just as they are layed.
 

I marked the eggs and put them in the incubator. This time I have weighted and measured them. I will repeat it by the end of incubation.

 

 

From top left to top right

1) 6g.  30,32mm x 18,31mm x 18,32mm
2) 6g.  29,30mm x 17,60mm x 18,16mm
3) 5g.  26,6mm x 18,28mm x 18,3mm
4) 5g.  26,43mm x 18,48mm x 18,28mm

Later, at 18:00, 8 hours after putting them to the incubator, the eggs start chalking, an indicator of fertility.

The fourth egg is still dented