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basking temperatures of common lizards |
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jopedder
Senior Member Joined: 24 Jul 2003 Location: United Kingdom Status: Offline Points: 55 |
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Posted: 08 Sep 2003 at 1:27pm |
hello again all, I have another surveying question for all: what is the best time of day to check tins? Actually I know this is the wrong question as what I actually need to know is what body temperatures the common reps need to get to in order to become active. I have recently purchased a thermometer to check air temperatures to tell when to stop checking tins in a morning and to see what time the temp drops to below 20 in the afternoon, but all this is usuless without knowing what temp the reps need. some not entirely scientific sources suggest 30c for common lizard, 12-20 for grass snake and 8-16 for adder, any idea if these are correct or what temp slow worms require? sorry for the spelling mistakes but my time on the library computer is nearly up and this machine will switchitself off! many thanks Jo
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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The figures for selected temperature in Beebee and Griffiths are, slow-worm 23 c Vivi lizard 30 c Grass snake 29 c Adder 33c taken from Spellerberg (1996); Avery (1997); Gaywood & Spellerberg (1996) selected temperatures being those the animal would maintain in an unlimited situation, activity starts at much lower temperatures of course - though if undisturbed under a tin I would guess they would wait until they reached the species preferred selected temperature. The time under tins would vary on how long the animal actually needed to reach this temperature and with the vagaries of the UK weather I'm sure there are no hard and fast rules. I've little experience of tinning other than the survey Lee Brady has set up in Kent, I find between 8:30 BST and 10:30 BST the most productive in the morning and if doing an afternoon check start after 5:00 BST - certainly plenty of slow-worms have shown up. A lot though must depend on the topography of the site as to exact times that are ideal. I think these were the times you suggested as best Lee? Edited by administrator |
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calumma
Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375 |
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Gemma: I tend to work in GMT
It's easier to predict morning surveys and the times you mentioned are reasonable. Afternoon times can be more tricky. During the summer, temperature under refugia increase rapidly in the morning but tail off very slowly in the afternoon. However, during spring and autumn temperatures can drop off much more quickly and refugia material can be very important. The afternoon time you state is fine during the summer, but I would tend to look from 1400 GMT during the spring/autumn (depending upon prevailing weather).. It is also very important to consider what the previous day's weather conditions have been, particularly rainfall and night time temperatures. Weather during the day can also strongly influence results. Showers with intermittent sun can produce very good results. Incidentally I recorded an adult male adder under a tin in one of my large woodland sites today at 16:29 GMT. Lee Edited by calumma |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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Just thought it would be worth mentioning that we started out today at 1400 GMT, we found adult viviparous lizards, very sluggish 7 under tins 3 under mats, strong westerly wind, overcast with showers, strange though only 1 slow-worm, last week starting at 1500 GMT I recorded mostly slow-worms under tins and mats and juvenile viviparous lizard only on top of them. Suggests slow-worms may use them a little later in the afternoon than adult viviparous lizards?
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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Here's a quick plot of animals found under/on tins over the last few weeks vs. time, It's a small data set: 19 slow-worms and 40 viviparous lizards Total of 50 refugia, 25 tins 25 roofing felt but it is beginning to show a trend. (I admit entirely that it may be influenced by greater survey effort at the times Lee suggested!). Though I guess such plots could be useful to track trends at a given site.
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jopedder
Senior Member Joined: 24 Jul 2003 Location: United Kingdom Status: Offline Points: 55 |
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Thanks for your information, although the few afternoon checks ive done have been later than your graph suggests is optimal, the morning survey times do match what I've been up to, but I've not been turning up reps. A lot of the sites I've been asked to survey are completely unsuitable habitats, but there are a few gems amongst them that 'should' have reptiles in. Maybe I'll have better luck next week! |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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The data set I have so far is too small to compare the materials vs. time, though I find animals under both during the time window given and it would be interesting to see if there is a significant difference between the materials. The time when both become too hot to expect to find animals seems about equal, though I've a feeling the roofing mats take longer to cool, so do have extended use in the evening and possibly on overcast/unsettled days. Lee, David and Tony have all stated elsewhere that there is often no hard and fast rules and results can vary from site to site as to which materials are the most effective. So far there is no greater preference shown by vivi lizards or slowies for either material for this particular survey. Interestingly this site also has a lot of carpet squares left over from a previous survey and also from abandoned cars, they have turned up a few animals on days where tins and roofing felt have had poor results, I guess due to different thermal properties of the material. We are using the pebbly stuff, it seems pretty good for lizards and I have found vivi lizards still asleep early morning, suggesting they use it as cover overnight as well as to thermo-regulate. From what little experience I have, I would agree with LeeÆs view that using a mixture of materials is the best way at any given site, rather than relying on a single material and this also seems to be wise with the unpredictable weather in the UK. Just as an addition to the graph above I also plotted survey effort over the 7 days the data was collected. I found the greatest effort was about an hour later than the morning peak for finds, suggesting it would be worthwhile making an earlier start in the morning. |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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revised graph, horizontal lines show survey times, |
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calumma
Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375 |
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Gemma: although your dataset is not complete your observations tally with my own. There is a trend for viv lizards to peak before slow-worms in the morning and to be seen again later in the afternoon. I suspect that this is largely due to viv lizards basking on refugia rather than under.
Your note about sleeping animals under refugia is quite true. In fact animals will also hibernate under refugia as well, so care must be taken not to disturb refugia during the winter. During management work at a site in Canterbury we found some old carpet tiles. See what we found underneath... All tiles were carefully replaced and the area left undisturbed! Lee Edited by calumma |
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test
Member Joined: 29 Apr 2008 Status: Offline Points: 1 |
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Hi Lee, as you know I've been recording viviparous lizards as "on" or "under" mats, I think they often start off under the mat then use the upper surface once they have warmed a little and perhaps feel less vulnerable.
I did notice on the most unsettled day of survey so far, wind, rain and cool we found a lot of adult viviparous lizards under the refugia around 1400 as mentioned above, suggesting they change how they use the refugia with conditions. One would guess that if observations were all of lizards on mats, an earlier start might reveal good numbers under refugia during the warm-up period. Edited by administrator |
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