the online meeting place for all who love our amphibians and reptiles
Home Page Live Forums Archived Forums Site Search Identify Record Donate Projects Links
Forum Home Forum Home > Herpetofauna Native to the UK > Grass Snake
  New Posts New Posts RSS Feed - Floods
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Floods

 Post Reply Post Reply Page  12>
Author
Message
longcrippler View Drop Down
Member
Member


Joined: 11 May 2007
Status: Offline
Points: 19
Post Options Post Options   Thanks (0) Thanks(0)   Quote longcrippler Quote  Post ReplyReply Direct Link To This Post Topic: Floods
    Posted: 01 Dec 2012 at 10:40pm
If a hibernating snake is immersed in floodwater, will it wake up and escape, or will it drown? And how long could it survive under water?
Back to Top
Suzy View Drop Down
Senior Member
Senior Member


Joined: 06 Apr 2005
Location: United Kingdom
Status: Offline
Points: 1383
Post Options Post Options   Thanks (0) Thanks(0)   Quote Suzy Quote  Post ReplyReply Direct Link To This Post Posted: 02 Dec 2012 at 12:27am
Are you thinking of anywhere in particular Mark?
Can you email me sometime - things to discuss.
Suz
Back to Top
will View Drop Down
Senior Member
Senior Member


Joined: 27 Feb 2007
Location: United Kingdom
Status: Offline
Points: 1824
Post Options Post Options   Thanks (0) Thanks(0)   Quote will Quote  Post ReplyReply Direct Link To This Post Posted: 02 Dec 2012 at 10:18am
they'll drown, for sure.  Mammals like hedgehogs have a chance of swimming away, but a torpid reptile is a gonner.
Back to Top
Noodles View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05 Dec 2010
Location: United Kingdom
Status: Offline
Points: 534
Post Options Post Options   Thanks (0) Thanks(0)   Quote Noodles Quote  Post ReplyReply Direct Link To This Post Posted: 03 Dec 2012 at 2:07pm

I was thinking about this the other day in relation to Suzi’s population of garden slow-worms.

Temperate bat species have the ability to self regulate body temperature to within 1 or 20C of ambient and will typically select cool to mild (2-100C) sites with high humidity during winter torpor. Bats can also knowingly self rouse at any time no matter what the environmental conditions may be; however, this does result in a significant demand on the animal’s fat reserves, potentially impacting on the ability of the animal to survive the winter. Despite this, bats do regularly self rouse in winter to make physiological adjustments, respond to dangers, alter roosts, drink, sometimes eat/mate and probably also to facilitate a healthy immune system.

Obviously cold blooded animals in temperate climates cannot do this, which makes me wonder about the areas they do select for hibernation. I wonder a) what are the minimum active body temperatures required by our native reptiles? b) how important or finite are fat reserves in hibernating reptiles for brain function/aiding mobility in cooler conditions etc and c) what temperature/humidity conditions do optimum hibernation sites offer?

If I had to speculate, I would think ideal conditions for a hibernating reptile might include high humidity with temperatures often, or occasionally, above the ambient and hovering near the animal’s minimum active temperature. This would aid the reduced rate of metabolism typically required in hibernation, as well as providing minimum temperatures suitable for minor and occasional mobility. These must be important considerations for any animal that is torpid for extended periods of time (to avoid danger, make spatial adjustments, drink etc). Are there any studies/publications on hibernation requirements in the UK? Caleb, Will? It is an area I would like to explore further.

I wonder are Suzi’s slow-worms exploiting the artificial thermal properties of their surroundings and entraining their period of daily/circannual activity accordingly. There is clearly a physiological need for all non homeotherms to hibernate but i wonder what constitutes a minimum period of successful hibernation in reptiles, with clear physiological benefits come spring?  

Back to Top
Iowarth View Drop Down
Admin Group
Admin Group
Avatar

Joined: 12 Apr 2004
Status: Offline
Points: 740
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iowarth Quote  Post ReplyReply Direct Link To This Post Posted: 03 Dec 2012 at 2:40pm

There are a number of interesting questions raised in this post. Just some thoughts about one or two of them.

Starting at the beginning we perhaps need a slightly better definition of "immersed in water". For example, common lizards living in marshy/flow country habitats have been recorded as hibernating well below water level in air pockets trapped in the root structure. It is far from unknown for various reptiles to emerge after flooding so presumably they too are taking advantage of such air pockets.

The question of ideal temperatures for hibernating is far more complex. At one end of the scale we have animals such as the common lizard again that can withstand temperatures at or close to freezing. Not quite so extreme are terrapins such as European Pond Tortoises which can be seen to be active below the ice in ponds during winter - and that temperature cannot be far above freezing.

Humidity is another variable. Certainly a degree of humidity is desirable but it can be excessive. Looking at Lacertids, for example, from experience I know that sand lizards do not tolerate excess humidity. Green lizards and Schreibers Green Lizard are actually slightly more tolerant and common lizards extremely so. The Wall Lizard family are about as tolerant as sand lizards while animals such as the Balkan and Caucasian Green Lizard are far less so.

Although these statement move outside the UK species they do serve to illustrate the differences bearing in mind that they are all capable of living naturally in the UK and, indeed, occur in temperate climate ranges.

Incidentally, with the genus Lacerta, all that I know of appear to derive adequate physiological benefits from hibernation periods as short as two months. (based on hibernation commencing mid December and ending mid-February followed by normal reproductive activity/success) 

Hopefully this helps - although in practise I have no doubt that it will simply confuse further!

All the best

Chris

Chris Davis, Site Administrator

Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED)
Back to Top
Liz Heard View Drop Down
Senior Member
Senior Member


Joined: 27 Apr 2010
Location: South West
Status: Offline
Points: 1387
Post Options Post Options   Thanks (0) Thanks(0)   Quote Liz Heard Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2012 at 12:02am
thanks for taking the time to share your expertise with us Chris! very interesting.

this totally flat, Grass Snake, Viv and Amphibian site recently flooded. it lies, cut-off, between twin river channels (BIG 1s)/urbanisation and is effectively an inland island.

some of it floods quite regularly, however the recent deluge was the worst ive seen here. even the raised footpaths criss-crossing it were underwater. if you didnt know the location youd have had no idea where the river channels were! it rose many, many feet and a nearby electricity powerstation escaped engulfment by the narrowest of margins!

this pic was taken a few days after the worst of it:




of course, the animals will be used to these conditions somewhat, but since the flooding was particularly severe this time, im gonna make resurveying this site a priority in spring!
Back to Top
Caleb View Drop Down
Senior Member
Senior Member


Joined: 11 Apr 2011
Status: Offline
Points: 658
Post Options Post Options   Thanks (0) Thanks(0)   Quote Caleb Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2012 at 9:48am
Originally posted by Noodles Noodles wrote:

Obviously cold blooded animals in temperate climates cannot do this, which makes me wonder about the areas they do select for hibernation.

Common frogs hibernating under water can do this to some extent, as they're still active at very low temperatures. Apparently their temperature preferences depend on the amount of dissolved oxygen in the water- if oxygen levels are low, they prefer very low temperatures:

Originally posted by Noodles Noodles wrote:

Are there any studies/publications on hibernation requirements in the UK? Caleb, Will?

I don't know any off-hand, but I have a feeling there was a bit in Appleby's book on the British snakes- I'll have a look later on.

Back to Top
Noodles View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05 Dec 2010
Location: United Kingdom
Status: Offline
Points: 534
Post Options Post Options   Thanks (0) Thanks(0)   Quote Noodles Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2012 at 10:58am

Thanks Chris. All these hibernation sites you mention must have at least one thing in common; they simply can't maintain temperatures below -1 on a regular basis. No living animal I can think of will tolerate freezing of the cell interior, although I believe a small number of frogs and turtles have evolved to produce a type of natural antifreeze.

Also since water reaches its greatest density at around 40C and sinks, bottom hibernating turtles, terrapins, amphibians and possibly air bubble residing lizards!? do have the advantage of a stable and relatively mild environment that is unaffected and unaltered by the changing weather conditions (provided some form of respiration is possible). In this scenario the animal can perhaps a) maintain necessary minor activity functions, to promote health etc b) guarantee that it will remain defrosted throughout the winter c) and experience minimum loss of, or need to find, water.

I just can’t see any advantage in a cold blooded animal (or homeotherm) selecting anything other than a warmer than average winter site, (enabling some mobility to access different thermal gradients/elevations within the hibernaculum) or a site that is guaranteed to provide a safe retreat, with temperatures at the minimum activity range with water availability (e.g. lake bottom).

I still think humidity or access to water must play a massively important part in winter site selection (particularly in amphibians) since the need for regular water intake/avoidance of its loss is so intrinsic to the function of life. In our (at times) mild maritime winter climate it would be advantageous for an animal to respond to these changes in order to make physical adjustments and/or to exploit the necessary resources.

Cheers 

P.S. Thanks for yet another useful paper CalebBeer I will have a look in Appleby when i get home, please don't trouble yourself any more.



Edited by Noodles - 04 Dec 2012 at 11:06am
Back to Top
Rob_H View Drop Down
Member
Member
Avatar

Joined: 31 Oct 2003
Location: United Kingdom
Status: Offline
Points: 14
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob_H Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2012 at 7:04pm
Many animals can actually freeze their cells, even common lizards can freeze the lower half of their body (mostly the muscle tissue) by massively raising cellular glucose levels.... The resulting ice crystals are too small to cause damage to the cell membranes. I believe they simply stuff glycerol or another anti-freeze into their brain tissue and major organs which means they can survive temperatures as low as -4C. Not sure about the other native herps, although wall lizards are known to have no resistance to freezing temperatures.

Remember that a hibernating herp will be using extremely small amounts of oxygen as well, and their brains are extremely resistant to hypoxia. I wouldn't be surprised if many species at their minimum temperatures could survive several days submerged. I suspect what Chris mentioned is the most realistic though; many burrows will have some pockets of air, and flood waters even in mid winter are likely to be just warm enough (even water under ice has an interesting tendency to rarely get below 4C) to allow some movement to find a pocket, depending on the species.

Cheers,
Rob
Back to Top
Noodles View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05 Dec 2010
Location: United Kingdom
Status: Offline
Points: 534
Post Options Post Options   Thanks (0) Thanks(0)   Quote Noodles Quote  Post ReplyReply Direct Link To This Post Posted: 05 Dec 2012 at 10:34am

That is interesting, thanks Rob. The point I was making was that there has to be some form of antifreeze mechanism for cell 'freezing' to occur; meaning there is no animal that can technically be frozen, thawed and expected to function afterwards. 

I really didn't know the use of glycerol as antifreeze occurred in our native species, which is very interesting. Does this occur in many UK species (snakes etc) do you think? Presumably any hibernating reptile with fat reserves has the ability to produce it but how much of a drain on these reserves is glycerol production in say a Common Lizard and, as a result, how long can tissue be successfully 'frozen' for? I wonder is this a partial reason why Common Lizards retain such large fat reserves in the tail; to adapt them to more hostile, wetter and more prone to freezing environments. Presumably a lizard with a lost tail would not be at an advantage in a frozen hibernaculum! 

Species that do not use glycerol in cell protection would surely benefit from a warmer than ambient hibernaculum above the minimum activity temperature range, although it does seem logical to me now that all temperate evolved species of reptile would have this ability to some degree. I’m sure it’s all very complex between species!

A really interesting and current topic, given the recent weather, and thanks again for taking the time to reply Rob, Chris, Caleb.... 

Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 11.06
Copyright ©2001-2016 Web Wiz Ltd.

This page was generated in 0.109 seconds.