divendres, 30 de març del 2012

Wall lizards

The spring is here. Most of the plants are sprouting. I have found some dragonfly larvae an some water beetles, still small sized. Water fleas are moving around, forming swarms in the water. On the surface, the water striders skate, fast and not easy to catch with the camera.

Aquarius najas (=Gerris najas)

The terrapins, after a week of intense sexual activity, have taken a break.  I haven't seen them mating for the last couple of days. In fact today the male has been all the morning out of the water, hidden among the vegetation, while the female was swimming around.


When I noticed that in the last 4 hours he had not moved, I took him. I wanted to check he was not ill. He looked well. I put him in the water and he swam normally. I offered him food and he took it. All seems to go well.

Regarding the female, she has eaten quite a lot. I have offered her the food in the form of pudding. Another day I will talk about it, but I use it because it doesn't leave debris around and it is easy to pick up what they do not eat. It helps to keep the water in good conditions.

Eating the pudding


The female at some distance

Wall lizards are the other reptile inhabitants of the pond. Maybe because they take me to childhood, I specially appreciate them. Lean and agile, they are naturally confident and they feel a great curiosity about what happens around them. When you approach them they turn they head to better assess the situation. If you come too near, they fly away, but if you stand still, they reappear. They are wild animals and they are there for their own decision, this adds charm to the situation. I think the pond offers them a good habitat. There is water (I have seen them drinking from the pond) and there are plenty of small insects and arachnids which they eat. The pond is south facing, so there is plenty of sun, which they enjoy.

The coloration and proportions suggest it is a female.


The aspect suggests it is a male. 

In this case the tail is regenerating. Wall lizards tail off very easily. When this happens the detached segment performs abrupt movements and contortions that mislead the predator while the lizard escapes. In this case it worked. Although they regenerate the tail, is has a different color and the scales look different. It was probably done by a cat or a bird. Cats, on which I personally believe that should not be let out of the houses, are especially problematic for wall lizards. A fence prevents the access of cats to the pond area. I think this has benefited the lizards.


The picture captured the moment when the male prolapsed the hemipenis. I don't know why he did it.

divendres, 16 de març del 2012

First mating of the season

Yesterday morning, about half past nine, I saw the terrapins mating for the first time so far this year.







In midday, with spring temperatures (more than 23ºC in the shadow) they were both sunbathing, in different places. 
Next week rain is expected, but I do not dare to say that they will stop mating in spite of lower temperatures. 
This morning they started again.

dilluns, 12 de març del 2012

Feeding and...

In Ernst&Lovich book and in articles I have talked about before, there is some data about this species behavior when the hibernation finishes. In Pennsylvania, they become active at a water temperature of   3ºC (other species don't do it until the water reaches  8-10ºC),  they can courtship at temperatures of 8,5ºC and they start feeding when the water temperature is about 14-15ºC.
In the northern areas of their range, the lowest air temperature at which they have started activity and courtship is 2ºC (it doesn't mention the water temperature)

Yesterday I saw the two terrapins. I don't see them often, the night temperatures are still cold. Anyway, yesterday, both, the male and the female, ate an earthworm. By the end of the month I will know the water and air temperature at this moment, but I don't think it is too different from the one that I measured when the male ate for the first time on February the 26th. (12,61ºC and 8,61ºC at 10 and 50 cm depth).






As it happened in February, the male approached the female but any chasing started. She ignored him. The pictures are somewhat blurry because the animals where in the deepest part of the pond. I don't think the temperature was lower than 8,5ºC, so, some chasing will start soon hopefully.



At 50 cm depth, the female in front




dijous, 1 de març del 2012

From winter to spring in 15 days

The first half of February has been the coldest of the winter, while the second half is being almost spring.

Air temperatures in the shadow, 5 cm above the ground. The coldest day was on February the 12th at 7:00 am, with a temperature of  -7,54ºC. At 10 cm depth the water was at  1,08ºC , at 50 cm 4,09ºC.




Water temperature at 10 cm depth






Water temperature at 50 cm depth. In the coldest days, in the bottom of the pond the temperatures were lower than 4ºC, they reached 3.59ºC.  It wouldn't have happened if the pond was deeper.



Last day I posted pictures of the turtles swimming under the ice in the morning. The data logger temperatures were:

February the 8th  9:00 (half an hour before I saw them)
Air -4,6ºC
Water at 10 cm depth 1,08ºC
Water at  50 cm depth 4,09ºC

February the 10th 9:00
Air -3,07ºC
Water at 10 cm depth 1,08ºC
Water at 50 cm depth 3,59ºC

They were swimming superficially, at less than 10cm depth.

Since the 15th the temperatures have been increasing gradually. This last week there has been a marked temperature contrast between the  day and night, with spring temperatures in the midday.  Now I often see the turtles, sunbathing with half closed eyes, very confident. On Sunday the 26th, around 4:00pm, I saw the male nibbling at the filamentous algae that grow in the pond. I threw an earthworm near him and he ate it. The air temperature was 23,83ºC, water at 10 cm 12,61ºC , water at 50 cm  8,61ºC. 
That day I added water to the pond with the hose. I saw a wall lizard (Podarcis hispanica) approaching by the wall I had sprinkled. It looked as though she felt attraction towards the water. I sprinkled the wall again and she started licking the wet stones. She did it for a long time, maybe it was the first time she drank since hibernation (this has been a very dry winter). The heat, the wall lizards, the turtles moving, the almond tree flowering, the birds singing... I also felt the spring coming.