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Grass snake scars |
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Robert V
Senior Member Joined: 06 Aug 2004 Location: United Kingdom Status: Offline Points: 1264 |
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Stuart / Rob,
please lets get one thing straight. I AM NOT ridiculing anyone ok. And I am NOT saying that my opinion is any better than anybody elses. But have you not heard of Ockham's Razor? Ie: that in science the most obvious and most likely explanation is very probably the correct explanation - or do not hypothesize more than strictly necessary unless evidence leads you to assumption.
You ask me to think about raptors. Ok. Lets think about it for a second. Why would a hawk swoop down at 65 miles an hour to attack a snake for food and not make any marks to the upper or flanks but only straight lines on the ventral scales - even a complete novice in herpetology would tell you that is beyond reasonable assumption, if you guys have any experience of nature taking its course, you would reason that it just doesn't work like that.
Genetic mutations - wouldn't we also be seeing 3 eyes, forked or disjointed tails, and all manner of uglys?
I'm sorry, on this occasion I think I'm being completely logical, if you have a counter argument, lets see YOUR evidence to back it up.
In my pic, you can see two different depths of scar and a clear thorn entry wound. I simply can't see how you could think this represents anything else.
Cheers.
R
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RobV
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dave fixx
Senior Member Joined: 13 Mar 2007 Location: Wales Status: Offline Points: 411 |
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an example of this from earlier this year in North Wales.Have we considered Al Qaeda ? Edited by dave fixx - 24 Aug 2011 at 9:48pm |
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Dave Williams
davewilliamsphotography.co.uk |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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These sort of scars or injuries can well be caused by all the discussed reasons.
I personally believe that the scars on the snakes I have captured (including scars on the dorsal surface) are in fact caused by a predator - now the 'feigning death' behaviour used by large grass snakes would lead to the snake escaping and thus these scars would then be able to heal over. Large snakes tend not to have a distinct yellow/black collar and one reason is possibly this isn't as effective as a deterrent to predators but it is in smaller younger snakes - have you notice how vivid the collar can be in younger animals? Anyway it is possible that thorns could cause injuries to snake bellies but so can the talons of a raptor which grip the underside of the snake. In some cases (I imagine) injuries also occur on the top of the animal just like this one pictured |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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PS there is no evidence to support conclusively how these injuries were created. circumstantial evidence and theories so far.....
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stuart
Member Joined: 26 May 2005 Location: United Kingdom Status: Offline Points: 31 |
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If it is not your intention to ridicule other peoples suggestions then may I suggest you refrain from using the word ridiculous in your response to those suggestions?
Anyway back to the interesting stuff-
I think the limited gene pool suggestion would as you point out likely to manifest itself in other ways as long as the abnormalities were not compromising the ability of the animal to survive.
The tracking suggestion I think would have resulted in a more ordered/neater scar. So far from my point of view at least I think the two most likely suggestions so far remain either bramble thorn damage and raptor attack.
Firstly, we have to accept that any photo cannot constitute proof of cause on its own.
That said, I think the picture you posted does add weight to your suggestion of bramble damage and to be honest its the first time I have seen what looks like a scar that may have had a graduated entry/exit point. However,it appears to me that the most obvious wound barely seems to have broken through the scale and looks quite superficial, (the cause of the deeper looking wound is more difficult to determine as it looks like it could now be necrotic/scale rot). The site of the wounds is interesting in that I think-if brambles were responsible then wouldn't we also see scars all over their bodies as I would guess that the snakes would be moving against and under the thorns as well as over them? Would they not also be present on juveniles? To my logic it just seems a bit unlikely to me that a snake would somehow impale itself on a plant that is ubiquitous throughout it's range, even if fleeing attack. Applying the theory of Ockhams razor, I don't think your theory "fits" the evidence. -I don't discount your suggestion though but I think it unlikely.
The scars I encounter have a defined edge to them that suggests to me (at least) that they were made by something with a sharp edge. Also the wounds I see seem to have penetrated the snakes body much further as in Dave Fixx's newly posted image. The scars that I encounter are very similar to Dave's. To my eye and logic they suggest a raptor attack. The fact that the wounds are (in my experience) found on the ventral scales would (I think)add weight to my suggestion as the sole of the foot embraces the snake the talons would then recurve and penetrate the ventral scales.
The site that I observe has a breeding pair of buzzards and when the young were rung earlier this year it was noted that two freshly killed adult grassies were in the nest with the chicks. On two occasions this year I have watched the adults return to their nest being mobbed by carrion crows and the buzzard was carrying a sizeable grass snake, still very much alive and doing its best to escape, in its talons.
I am aware that the incidence of scars and the witnessed buzzard predation may be entirely coincidental, however this suggestion would seem to my mind to be within the realms of possibility and probably the most obvious logical explanation?
Next season I am going to record the incidence/site of these scars more methodically and will post further information/images if anyone's interested?
Regards
Stuart
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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Hi Stuart
I have a local grass snake population which I can also document their 'scarring' which to me would be found mainly in older larger snakes as they survive bird attacks etc Regards
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Robert V
Senior Member Joined: 06 Aug 2004 Location: United Kingdom Status: Offline Points: 1264 |
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Yes Stu, I would be very interested in next years results.
To me though, Daves photo merely confirms sharp objects such as thorns - because think about a snakes movement, very often moving laterally as well as forward in a weaving motion to gain purchase on vegetation etc, Daves photos I think shows something very sharp slicing the scales as the snake moves and even has pin prick entry wounds again (like my one).
Think about it, what shape would a talon have to be to make a flat short entry wound like daves photos show? Surely they would be four or five round or crush wounds?
R
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RobV
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stuart
Member Joined: 26 May 2005 Location: United Kingdom Status: Offline Points: 31 |
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Hi Rob
I think we will have to just accept that we see things differently, I look at Dave's photo and I think the scars fit with the pattern exactly as I would expect to see with a raptor attack!
To my way of thinking if brambles were the cause I suspect the snake would probably notice that it was impaling itself and presumably stop moving and extricate itself before doing any more damage. You would have thought that there would also be the odd record of snakes that weren't able to escape and had been found entangled on brambles ( I have am not aware of any but would welcome any references). Furthermore, I doubt the snakes weight would be sufficient to apply enough force to cut into its body that deeply and finally if brambles are such a hazard to snakes wouldn't the wounds be found on young snakes also?
-Roll on next season!
Regards
Stuart
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tim hamlett
Senior Member Joined: 17 Dec 2006 Location: United Kingdom Status: Offline Points: 1062 |
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hi all
interesting thread. i have no idea what may have caused the injuries but, from a lay persons point of view, though they look like they could have been caused by bramble thorns, the idea seems somewhat counter-intuitive. brambles seem to form such an important part of the snakes habitat, e.g. dense impenetrable (for most potential predators) cover and they are so often found around it that I would have thought, if they were vulnerable to such injuries, that they would be much more common. just think about the speed with which 'dancing' adders shoot through such vegetation without sustaining obvious injuries. just my thoughts. tim
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Robert V
Senior Member Joined: 06 Aug 2004 Location: United Kingdom Status: Offline Points: 1264 |
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Yes Stu, very differently!
In your photo top of page one which opened this debate, there are fairly long straight lines on only the evntral scales. Can you say exactly how you feel this could have been made by a raptor? What are we talking here, a kestrel, sparrow hawk, Buzzard, which? My brother has a kestrel, harris hawk and a barn owl and all I can tell you that when they sit on your gloved hand you can feel the pressure digging through the reinforced leather gauntlet crushing your hand.
I am genuinely intrigued as to how you feel the raptor would attack these snakes and why you think that on the subjects here photographed, there is no sign of scarring above? Unlike that of Jon's photo which shows the ragged tears that I would expect to see after a raptor attack on Natrix.
And as for the snake noticing the damage done; well I can only relate to you an incident that happened when I used to keep King snakes etc. I had a thermostat pack up on me and the heat pad got extremely hot. But the snake didn't move off to a coller part of a cage - it stayed underneath it and got burned!
And I have seen both adder (on a Devon Cliff) and a Grass Snake badly snagged on brambles, the Grass snake concerned left a trail of blood on the grass after release.
Rob
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RobV
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