Greetings from the UK!

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Re: Greetings from the UK!

Postby Daniel Bohle » Tue Dec 01, 2015 11:45 am

Well, I´m a bit too lazy to take out my poor english but ok ;-)
I´m still working on my date from 2006-2015, around 600 fielddays and around 7000 observations.
And this is the problem – fieldwork is just the tiny party of the work!
Let me say, I need at least another year until I have the basic data finished.
For each animal I found I need a few seconds or often hours until I knew if it is well knows or new. Still a few hundred left :cry:

Whatever, it always feels as if numbers are getting worse all the time but looking at the numbers per day/hour that’s not complete true – at least not for every subpopulations.
But animals per day/hour is too influenced by me and my personal still growing snake hunting skill.
The pure number of different animals each year is a way better indicator to draw a conclusion!

And we have to look at one more thing. These Subpopulations are all located deep in the forest. Since 1990 they chanced the forestry due to nature protection things.
They stopped complete to cut huge areas of trees at one moment. Now they just take out a few bigger trees and start to plant new ones direct.
In other words, since 1990 they did everything to get rid of even the smallest open area inside the forest. So habitat loss is dramatic!!!
I´m sure without all the work we did here to safe the last places from getting pure dark forest the numbers would have declined dramatic and at a lot of places down to zero!
But this also means a permanent changing habitat for the animals with more or less a lot of disturbance by me because of cutting trees and monitoring. Of course I don’t catch them for monitoring and we cut mainly during the winter!
At some of these spots Numbers are still high … maybe just because they have no real choice to leave these places because there are no other ones...
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Re: Greetings from the UK!

Postby Aleksandar Simovic » Tue Dec 01, 2015 2:24 pm

I care too much about disturbance on sites, but i know few sites (i am working on them also) where snakes dont give a f*** about anything, they are basking, mating, moving, eating in front of hundreds people, and i am not talking about Nnatrix and Ntessellata and population is BIG!

I remember my friend Ivo Peranić having found some 40 adders within a few hours, at a small but "fruitful" locality, some years ago. Nowadays if you find a few at the same locality, searching for half a day, you may count yourself quite lucky. I don't like it at all. It isn't fair.
So, has something been "going on", or rather, going WRONG, or what?
Any opinions/experiences from others?


Well, its a just a day. I remember two days in a row this year for example, almost identical weather conditions, first day 11 balkan/bosnian adders (4 hours), and the next day more then 30 balkan/bosnian adders in less then 2.5 hours on the same site. So even if we thing that we know much about snakes, we dont everything and there are always discrepancies, so we need to be every day on our research sites. :lol: :lol: :P
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Re: Greetings from the UK!

Postby Jeroen Speybroeck » Tue Dec 01, 2015 2:29 pm

Thanks, Aleksandar, that simple example of yours surely may fit with the low recapture rate and associated population size estimation and trend monitoring difficulties. A lot of herps are though that way.
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Re: Greetings from the UK!

Postby Aleksandar Simovic » Tue Dec 01, 2015 2:41 pm

Jeroen,

i started last year CMR on bosniensis, and yes, i dont have too much recaptures, but on the other very disurbed one i talked about i have many many recaptures, although species is different (caspius and longissimus).
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Re: Greetings from the UK!

Postby Jeroen Speybroeck » Tue Dec 01, 2015 4:53 pm

Aleksandar Simovic wrote:Jeroen,

i started last year CMR on bosniensis, and yes, i dont have too much recaptures, but on the other very disurbed one i talked about i have many many recaptures, although species is different (caspius and longissimus).


I bet if I wouldn't be so salamander-obsessed all the time, I would have tried to dig into the literature on that for a bit, because it's really interesting. I do recall that there's quite a difference between colubrids and vipers, though. Matters like habitat use, activity patterns, ... surely play a role, and are (obviously) rather different between those species. Then there's the matter of how you detect them. Are you searching all 3 (bosniensis, longissimus, caspius) visually? Or one or more underneath artificial (or natural) substrates?
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Re: Greetings from the UK!

Postby Aleksandar Simovic » Tue Dec 01, 2015 8:42 pm

I do recall that there's quite a difference between colubrids and vipers, though. Matters like habitat use, activity patterns, ... surely play a role, and are (obviously) rather different between those species.


yes ofcourse Jeroen.

Are you searching all 3 (bosniensis, longissimus, caspius) visually? Or one or more underneath artificial (or natural) substrates?


I am not big fan of a flipping, and i only search visually, although there is almost nothing to flip, just big stone walls (on colubrids site).
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Re: Greetings from the UK!

Postby Jeroen Speybroeck » Tue Dec 01, 2015 9:30 pm

Aleksandar Simovic wrote:
Are you searching all 3 (bosniensis, longissimus, caspius) visually? Or one or more underneath artificial (or natural) substrates?
I am not big fan of a flipping, and i only search visually, although there is almost nothing to flip, just big stone walls (on colubrids site).

OK, that makes it even more interesting. Would love to see some results (if at any point in time you'd be up for sharing or publishing it).
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Re: Greetings from the UK!

Postby Berislav Horvatic » Tue Dec 01, 2015 10:01 pm

Aleksandar Simovic wrote:I care too much about disturbance on sites, but i know few sites (i am working on them also) where snakes dont give a f*** about anything, they are basking, mating, moving, eating in front of hundreds people, and i am not talking about Nnatrix and Ntessellata and population is BIG!

That's one of the aspects I've had in mind - that they are (sometimes? someplace?) not that much "delicate" after all.
There is a place in Croatia - the ruins of a big medieval castle - swarming with V. ammodytes as well as tourists
(especially on weekends), and none of the parties seems to take notice of the other one... We actually felt quite
"embarrassed" catching vipers in front of the noses of the passing tourists, free climbers, schoolchildren... Whenever
any of the humans around noticed what was going on, and showed interest (or astonishment), we took the opportunity
to "educate them on spot", of course. It's a "sacred duty", and in most cases it worked well. But without us (the herpers)
interfering, the two species seem to just happily ignore each other - within a meter or so. The vammos don't "relocate"
and the human visitors keep comming in swarms.
If anyone wants to see that in vivo, let me know and be my guest. Five Germans already have, and they enjoyed it
very much:

BH_NN_0677_RED.jpg

BH_NN_0633_RED.jpg

BH_NN_0682_RED.jpg

(Sale, Serbs also invited, especially you, of course. Mentioning Germans was just the statement of a fact,
nothing else.)
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Re: Greetings from the UK!

Postby Berislav Horvatic » Tue Dec 01, 2015 10:52 pm

Jeroen Speybroeck wrote:From probably one of the most intensively monitored berus populations in Europe, however, I know that in CMR studies the recapture rate is (very) low, making monitoring of population size a delicate affair. In other words, you guys may be right to see declines, but at least with berus I am cautious to draw conclusions without (more) solid data.

IMHO, regarding our monitoring site of V. berus bosniensis in the environs of Zagreb, the CAPTURE rate went down (which is simply sad), and the RECAPTURE rate was far too low (let’s say, to my “taste”...) - yielding unrealistically low density of the local population (by any of the calculation methods). Worse than a "delicate affair" - we just don't know what's really going
on there after all that "monitoring"... Noone cheated, we all worked as best we could, including myself, but I'm deeply dissatisfied with the results. So, as you put it so mildly, "a delicate affair" indeed. (I personally felt it as a defeat, but that's just an emotional reaction, not to enter any publication...)
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Re: Greetings from the UK!

Postby Jeroen Speybroeck » Wed Dec 02, 2015 12:07 am

There are of course different levels of disturbance, but my initial mention of it was a cheeky referral to herpers herping (= more disturbing than people just passing by). That site does sound interesting, though. To put things in perspective, this is usually not the one and only problem a collapsing population is facing, of course.

Berislav Horvatic wrote:the CAPTURE rate went down (which is simply sad), and the RECAPTURE rate was far too low

Well, I'd say the first can be unrelated to the actual population trends (= not reflect the true trend) and stay (even with tons of sampling effort) unknown, especially if the (more species-related) recapture rate is very low (but, and there's the rut, also if abundance is truly low). This may be phrasing it too chaotically, so, in short, population abundance largely depends on detectability and survival, both of which are reflected in recapture data. I'm only starting to really dig in to this stuff myself (in a salamander context, obviously) but it sure is fascinating.

The luck/advantage I have with fire salamanders, is that they live long (*) and occur in a habitat that is not changing all that much. In contrast to reptiles (bearing Kristian's contribution in mind) they have little trouble with loss of open spots. No logging or crazy stuff, is going on, so in theory, I'm expecting less human influence in any trend I might discern, which may be dramatically different in adders. In the highland fragmented landscape of Belgium in particular (like I said) the relocation option that Kristian mentioned might be unavailable.

(*) This is "luck" for recapture studies, because it gives you more time to recapture individuals, but in terms of establishing the impact of changes in the environment, it might actually be harder, or at least take longer to establish.
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