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Distribution knowledge, filling the gaps |
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-LAF
Senior Member Joined: 03 Apr 2003 Location: United Kingdom Status: Offline Points: 317 |
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Posted: 17 Jun 2004 at 3:28am |
Okay, a bit similar to my recent posts but this really got me thinking. I've observed both common lizards and slow worms at sites not apparantly covered by current distribution maps (slap on the wrists, must start submitting records! Yeah, I know..) and this has really got me thinking. About two species in particular, the smooth snake and the sand lizard. Both these species are now known from a fraction of their historic range. But how confident are we that these animals distributions are fully (or even majoritively) known?
Let's start with Wales. Sand Lizards dissappeared there, the books tell me, as a result of people pressure and the boom in the seaside tourist industry. Okay, but between a lot of north and north west welsh towns and holiday camps are BIG expanses of, well, very little. Before we decreed the sandys extinct in that region just how thorough was the surveying of possible sites? Having seen how small sites can hold remarkably large populations of this animal the task must have been horrendous. And what about Devon, Somerset, Cornwall? All these counties have vast areas of reptile friendly habitat, so just how much has been covered? Basically, the notion struck me that there must be SOME sites out there with these species sat there unrecorded (and, therefore, unprotected). The question is, how many? While money is spent (and rightly so) on protecting these species, managing their habbitat and re-introducing them to known former ranges, I wonder how much effort and resources go into extending our knowledge of their distribution? Do most records come from people actively searching in possible areas or simply from records by people who come across them? What about the gower peninsula for example. A few possible sightings of smooth snakes from there, but has anyone gone and left tins to survey? So they're probably not SSs but isn't it better to be sure? Obviously, resources are limited and the most efficient use of them is to use them where we KNOW they will yield results, but are we really in a position where we can take our knowledge of populations as gospel. Im not so sure. These re just my thoughts but I'd be very interested to hear peoples oppinions on this matter. One things sure, I'll be doing a lot of coastal walking this summer. Cheers, Lee. |
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Lee Fairclough
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test
Member Joined: 29 Apr 2008 Status: Offline Points: 1 |
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Hi Lee, Well just one experience going back many years, on a common in Surrey Sand Lizard and Smooth snake were considered extinct due to a major fire back in 1946. I observed sand lizard here way back in the 80's, duly reported it and was informed the site had been surveyed and none found. Introductions have been made since at the site. I know what I saw, so I must wonder along with you just how much effort goes into all this. |
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calumma
Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375 |
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Now don't get me started again!
Seriously though, I am constantly frustrated by many of the surveys that are undertaken in advance of various projects. Forgive me for widening the discussion Lee, but not only are surveys for some of the rarer species patchy in some places but so too are surveys for the more widespread species. It is particularly irritating when conservation based management works are undertaken on sites before full survey work (even presence/likely absence) has been undertaken. I can confirm that all of my negative records are sent in. Indeed I actually use negative records as an indication of overall survey effort. Even sites with good herp populations will generate negative records if enough visits are undertaken. Lee |
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-LAF
Senior Member Joined: 03 Apr 2003 Location: United Kingdom Status: Offline Points: 317 |
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Hi Gemma,
It's interesting you should say that. Beebee and Griffiths book says that smooth snakes are far more capable of survivng fires than lizards, partly due to their penchant for subterranian life and partly because they survive long enough to re-colonise 10-20yrs later once the habitat is back to optimal. If you saw sandys at this site (and I don't doubt for one minute that you did) then there should be a distinct possibility that smooth snakes remained there also. I guesse as an introduction site, though, that recent surveying must have been undertaken with a high degree of accuracy ??? Or do they not use tins for recording sand lizrds (I've certainly found sandys under tins though). Regards, Lee. |
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Lee Fairclough
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test
Member Joined: 29 Apr 2008 Status: Offline Points: 1 |
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Hi Lee, I know the survey was refugia based and assume the trend would have been for tin in the 80's. Smooth snake have also been reintroduced at this site in recent years, so I'm told, so I guess it's now a fudge as to whether or not the original inhabitants make up the majority of the populations or not. Though I've not noticed anyone taking any particular interest in finding out just what the distribution of either species is on the common. My work is mostly based around adder on bracken at the site so I suppose I'm no better! |
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