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Hatchling sand lizards |
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Iowarth
Admin Group Joined: 12 Apr 2004 Status: Offline Points: 743 |
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I certainly haven't seen any wild hatchling "darn sarf" as yet. If the behaviour of my sandies is anything to go by, problems started early on with very warm March days but bitterly cold nights. Consequently, feeding by the adults was, at best, sporadic and minimal. The deterioration in the weather started in April and apart from a brief good spell in May carried on that way. This evidenced itself with smaller than average clutches, with a lower viability rate and smaller than normal hatchlings - this despite time of laying being within normal bounds. But, circumstances vary not only from region to region but even within sites in close proximity. While a similar pattern in terms of results evidenced itself with many breeders, one or two had moderately successful years and one a "normal" year - thus demonstrating local variations. I believe that a significant number of "wild" eggs may have been affected by the excessive rainfall resulting in them being effectively drowned in some locations. Incidentally, I do disagree re. Wall Lizard incubation periods as in my experience they are identical (albeit in artificial conditions) - although the Wall Lizards frequently lay much earlier which produces earlier hatchlings. Additionally, since they often choose totally dis-similar incubation sites, frequently under stones or rubble they will not have been so affected by the rain although the lack of sunshine would still have had a negative effect. This is evidenced by their first clutches hatching much later this year - earliest late August down here - almost as late as we would normally be looking for young from second clutches. So far as adult behaviour in Sandies is concerned, a number of my adult animals disappeared in early "summer" (a term I use loosely!) and have not been seen since. I have no doubt that this summer has had a severe negative impact on wild breeding and, quite possible on adult populations as well. We have not seen any other deterioration in adult populations down here in recent years and as a consequence, so long as this summer was a one-off event, we need not be too concerned. Judging, however, from what Mike has said, and I certainly have great respect for his experience and knowledge of the "Merseysiders" it does appear that it could be cause for considerable concern up there. Demonstrably the situation is going to need continued monitoring which, again, Mike and his colleagues will doubtless continue to undertake. Chris |
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Chris Davis, Site Administrator
Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED) |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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A very comprehensive summary of the less than summery season, thanks Chris. I'm pretty sure sandies double clutch in good years in Dorset, at least on occasion (I saw a what I reckon was a gravid female in late July several years ago which then appeared a few days later very thin, just like a female post-egg laying, and several times I have seen tiny sand lizards seemingly fresh out of the egg in mid-late Sept). However it could also be that these are simply the result of late-laid first clutches - another case of more work needing to be done? either way, let's hope the recent trend for cool summers as a result of jet stream problems isn't here to stay...
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AGILIS
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1689 |
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Chris if any one knows its a bad year form La its you, Perhaps this has been the long term cold spring weather probs that have caused a rapid La decline in some of my sites that I have visited for years and have noticed them being thin on the ground apart from the usual habitat loss fires and the rspb etc .
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LOCAL ICYNICAL CELTIC ECO WARRIOR AND FAILED DRUID
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mikebrown
Senior Member Joined: 30 Jun 2005 Location: England Status: Offline Points: 108 |
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We also had a very cold and wet April and part of May, as well as June, and something we did notice this year was a real scarcity of adult female sand lizards being sited, compared to males, even in May and June, well after the expected end of the hibernation period. We would expect to see proportionately more males than females early in the season because of their greater activity and brighter colours than the females, but not such a high proportion as this year. Any suggestions as to whether this is weather related?
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Mike Brown
Merseyside ARG |
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Iowarth
Admin Group Joined: 12 Apr 2004 Status: Offline Points: 743 |
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Hi Mike, I agree totally regarding the prevalence of male sightings early in the season. In my experience females approach nowhere near the same level of visibility until the late stages of "cooking" their eggs preparatory to laying. As to whether or not the unusual and adverse weather conditions should affect females more directly (i.e. behaviourally) than in terms of egg production/viability I have no idea. It may be that much of their behaviour in the early months is related to "egg cooking" and lack of opportunity resulted in lack of visibility. But, in this case one would expect to see them in abundance in the few spells of good weather and I am guessing from your comments that this is not the case. I believe that it is most likely that the weather is the direct cause, together with its effect on food availability etc but beyond my rather vague and entirely hypothetical conjecture above I am at a loss to explain this. Chris |
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Chris Davis, Site Administrator
Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED) |
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GemmaJF
Admin Group Joined: 25 Jan 2003 Location: Essex Status: Offline Points: 4359 |
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Could one factor be mosaic basking Mike? I know male and female adders have different basking habits early season. The brighter smaller males will bask openly, the larger duller females will 'mosaic' bask, i.e. remain under partial vegetative cover. One can imagine in poor weather that the first tactic used by the males is more flexible and efficient, the females remaining under partial cover may though never quite get fully up to speed. With gravid female adder later in the season the pattern changes to initially mosaic basking on a given day, then when up to temperature basking more openly to aid the development of the young. In really poor conditions I could imagine animals being 'stuck' in the mosaic part of the cycle and and not becoming active enough to risk basking fully in the open. Perhaps this provides an explanation for why the animals 'should' be seen basking more openly to make up for poor weather condition, but in fact remain elusive? They are not able to warm up enough initially to risk basking in the open in poor conditions. Just in addition, I would think the situation would be compounded by long spells of poor weather, the females being in poor conditions making the whole process even less efficient. It would be an interesting study to see if such a 'threshold' exists and whether or not as I would suspect, it is different for males and females of some species.
Edited by GemmaJF - 14 Sep 2012 at 1:35pm |
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Iowarth
Admin Group Joined: 12 Apr 2004 Status: Offline Points: 743 |
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An interesting hypothesis Gemma. Certainly one that makes sense and I must say that in my vivaria the females do spend far more time than the males mosaic basking - and indeed, although I had never put two and two together as you have, this also applies to the relatively few females I see in the wild - i.e. most of those I do see are mosaic basking rather than out in the open. Perhaps Mike or Paul might also have some views on this aspect with their experience of Merseyside animals and, of course, Vicar re Wealden animals if he is reading this thread. Chris |
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Chris Davis, Site Administrator
Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED) |
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Ray999
Senior Member Joined: 07 Mar 2006 Location: United Kingdom Status: Offline Points: 124 |
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It has been a strange year.
With my captive animals my young male got up very early (end of Feb) but then acted strangly for the next 6 weeks becoming very thin, I thought I was going to loose him. The rest of the animals got up as expected. All 4 females were mated but again the 2 younger ones re-absorbed their eggs, the 2 older ones produced 15 eggs in total, they all hatched. Towards the end of the season they have probably behaved as expected, the older male went into hibernation in mid August the 2 older females went into hibernation at the end of august, the 2 younger females and younger male are still up but not feeding. On my visits to the dunes I would agree with Mikes comments. However on 1 visit in late April when the weather was just right for about 45 mins, I saw about 15 males and 3 females along with a few babies, though most were very young and probably in their first breeding year, but on visits after this the numbers were very low. Has there just been very few days when the weather has been perfect for monitoring, the amount of babies seen this autumn may be an indicator of how things are which uptill now the signs are not good. My first sighting of common lizard babies was the end of the second week of July the earliest I have known for this part of the world
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ray999
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AGILIS
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1689 |
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Going by the replies I would put this down to the weather and possible climate change,like the other year seeing sloworms in mid February not the norm. keith
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LOCAL ICYNICAL CELTIC ECO WARRIOR AND FAILED DRUID
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mikebrown
Senior Member Joined: 30 Jun 2005 Location: England Status: Offline Points: 108 |
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There is certainly a lot of truth, Gemma, in what you say about the female sand lizards tending to mosaic bask early in the season, making them difficult to see. However, I would have thought that as the eggs develope inside them in late May and early June, instinct would drive them more out in the open when the sun was shining, to allow their eggs to develope further prior to laying. Perhaps, as you suggest though, their eggs weren't developing sufficiently any way at an early stage this year, due to the cool, dull and wet weather.
It'll be interesting to see what Paul and John think when they return from their holidays!
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Mike Brown
Merseyside ARG |
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