Vipera Morning

[Daniel Kane]

Today I biked up to my local place for adders and viviparous lizards. Yesterday and last night it had been heavy rain and wind, but today the air seemed to have cleared somewhat. There was still about 90% cloud cover and occasional showers. On the way there I saw a few DOR Bufo bufo and a small Lissotriton helveticus, unfortunately also DOR.

My local place

I got there about 10am when it was 17*C and practically no wind, and within 20 minutes I had found an old sheet of roofing felt. Beneath was this:

Great!

Brilliant. Immediately I thought it was a single juvenile from last year. But a few seconds later 'the' snake moved slightly to reveal....

Two babies

Even better! Two individual week-old baby adders surely beat a single yearling. One of them had a very nice dorsal zigzag; wider than normal and with a paler centre. I'd love to see what this adder looks like in 5 years. The sun came out for a few minutes while I was photographing these two snakes, which allowed for some nice light.

Juvenile 1

Juvenile 2

These were just a metre or so from the entrance of a hibernacula used by a single male last year. Not 10m behind this feature I found my third snake of the day, the first adder I found by myself May last year. She's 62.5cm long now; 4.6cm longer than when I first saw her.

Female 1

She still doesn't like me very much...

It started raining lightly, on and off, just after I caught her, so I only took a few pictures. 5 minutes later I saw this little male coiled up in some moss not too far from the previous snakes.

Male 1

Then it really started to rain hard. I had to shelter in the forest for half an hour before the rain clouds blew over and let the sun out again.

Can you see him?

A bit closer

After a while watching him bask, I got some nicer photos of him. Now the clouds were coming in again, and it looked like it would rain heavily again.

Portrait

I have been trying for a while to get nice photos of adders and slow worms whilst they are tasting the air, but it is normally too cloudy to get a fast enough shutter speed. Today was my lucky day though! I think this one came out quite nicely:

Tongue-flick

There were many baby Zootoca running around the place too, but I saw no adults in 2 hours of being there.

Looking at the pictures on my laptop, I have identified both males and both juveniles are new to me. This brings the total number of different adders I've seen at this location to 11; 5 males, 3 females and 3 juveniles.

[Jürgen Gebhart]

The area looks great! Congrats to "your" new members in this area.
Juvenil 1 is a real eyecatcher!

[Jeroen Speybroeck]

I found my third snake of the day, the first adder I found by myself May last year. She's 62.5cm long now; 4.6cm longer than when I first saw her.

Does anyone know if this is a normal growth rate? Seems like a lot to me...

[Mario Schweiger]

Yes, quite a lot from 58 to 62.5 cm in one year!
I think, not normal in nature - but even in captivity I think a bit to much for 8 to 9 month activity
Daniel, might be a misidentification with another one, quite similar?

Mario

[Daniel Kane]

I don't know how much adders grow per year, but according to the book 'The Adder' by Peter Stafford, within 5 years from birth most adders will have reached about 46cm. Born at roughly 14cm long (as this years young were), this equates to about 6cm of growth per year in the first five years. It says growth then slows after the initial 5 years, so the snakes should be growing, on average, less than 6cm a year.

The other day I found this particular adder outside where she hibernated last winter. In 2009 I found her about 20m from that spot. This female is easily identifiable, fortunately for this . She has a dark patch in the centre of the frontal scale and a light area between the parietals;

Head, 22nd May 2009

Head, 7th September 2010

DSCF0084 (650x487).jpg (161.96 KiB) Viewed 8911 times

Apologies for the poor 2nd photo, but it's the only one I got of the top of her head on the day before yesterday. We can see that the head scalation is identical though. So we know that this is the same snake and not two similar ones.

The way I got these lengths was by taking a photo of her (flat) next to an object of known length, then using the 'Serpentine Widget's Snake Measurer' programme at home to find the total length. In 2009 I had to use my shoe to get an idea of her size. I know that this 'shoe method' isn't great, but measuring at the time (and again today to make sure) that marked line is 10mm long.

Length, 2009

In the 2010 picture, I have used a ruler to mark 5 and 10mm intervals, so I can get more reliable measurements than last year.

Length, 2010

So from these photos, the snake appears to have measured 59cm in May 2009, and 63cm in September 2010. What are your thoughts on this?

[Mario Schweiger]

Looks great that they grow so much in one year
and Serpentine Widgets works great too, I know.
A problem might be the relation between the reference length and the snake length.
This relation shouldnt be to high, so wrong adjustment of the reference will multiple often in the snake length.
Your example: 10 mm reference - 60 cm snake: 0.5 mm = +/- 30 mm at 60 cm.
So its better to use a piece of wood or plastic, exact 100 mm - or for smokers, use a cigarettebox.

They have changed the server, where they stored "Serpentines Widget" now a few times - and it was not available. But you may download it also here:
http://www.vipersgarden.at/ZIP/SnakeMeasurer.zip 1.5 MB

Mario

[Jeroen Speybroeck]

Even in those first 5 years, I cannot imagine growth to be linear. I suspect the growth rate will drop from each year to the next. Surely, after those 5 years, the rate will have dropped more than a bit and become close to zero after a certain number of years, resulting in a more or less asymptotic maximum size (at least for this species). This maximum size is of course subject to individual variation (in other words: has a +/- range). Also, I would expect a winter stop in growth, leading to a growth curve that looks like a stairway with the horizontal part of the steps being winter + the height of the steps become less with each step you go up.

I'd mainly blame the 'shoe method'. Your calibration unit (the shoe thing) is way too small in relation to the to-be-measured object (the snake). Apart from that, I think the method is quite OK; I also use it for Salamandra (http://rsbweb.nih.gov/ij/).

[Jeroen Speybroeck]

Your example: 10 mm reference - 60 cm snake: 0.5 mm = +/- 30 mm at 60 cm.

Indeed...

For Salamandra, which is of course smaller, I use my lens cap, which is exactly 6cm diameter, while the animals never superceed more than 20cm.

[Mario Schweiger]

Schiemenz, H. (1985): Die Kreuzotter. Die Neue Brehm Bücherei Bd. 332 gives following data (kept in outdoor pan) for growth:

Länge bei Geburt = length at birth
Geburtsgewicht = weight at birth
Häutungen = sheddings
Nahrungsmenge = weight of food
Körperlänge = length
Männchen = males
Weibchen = females

Schiemenz, page 81

Mario

[Jeroen Speybroeck]

Thanks, Mario. I think, this shows nicely what I expected, with the additional length gained within a year roughly being /2 of the previous year.

Here's what I was trying to explain with my stairway story (von Bertalanffy growth function with seasonality) =>



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