Frozen Frogs

[Deb London]

Originally Posted by Littlesparrow

This afternoon as the temperatures have been above freezing for a couple of days in Cheshire, I checked my frog pond, only to find all the large frogs have died, frozen to death. This is very distressing,my pond is a medium sized one and I have never known this to happen before.
Is anyone else having a problem with frozen frogs.http://www.wildaboutbritain.co.uk/fo...lies/frown.gif

There is some very interesting information in the 'big thaw' site that eeyore highlighted recently.

The findings seemed to suggest that there are a few things to be done, or at least to be designed into any new pond.

Correct me if I'm wrong people.

Things that may help:
Having a shallower pond of around 30 cm (contrary to previous advice which called for deeper ponds and very interesting from my point of view as I have always tried to create very deep ponds*).
Possibly keeping snow off the surface and possibly running a pump.
Having plenty of oxygenators.
Blanket weed and algae!

Things that don't/aren't thought to help:
Making a hole in the ice, any which way it might be done.
Having too many leaves and too much sediment on the bottom of the pond.

The answer to why frogs die probably involves the amount of available dissolved oxygen and might involve the build up of toxic gases. There is plenty more research yet to be done.

[*That said, three frogs were recovered when I emptied my large pond this winter to do essential maintenance. All three were living. I do have plants and the very bottom. There are some young water lilly and Aponogeton shoots that might have been photosynthesizing, possibly some Hornwort near the bottom, and an abundance of Water Soldier, which sinks in winter. I'm wondering if the latter might have been a godsend.]

[Littlesparrow]

Thank you Debbie, back on track with some helpful frog advise. I've been picking out any dead leaves from my pond and I'm thinking of cutting back the irises a bit more now there is nothing in my pond to disturb.

[bigdave60dog]

This has happened in various places before. They do not usually freeze to death as many suppose. They succumb to the build up of toxins in the water which are unable to escape to the surface as normally happens.
Expect much more of this as the temperature warms up. You may need to replace the stock with frogs at any stage of their lifecycle. Spawn is favourite some Wildlife groups have spawn exchange schemes.
Dave

[tom00_uk]

im not a fan of "spawn exchanges" you not only run the risk of disease being moved around
but also you run the risk of trying to raise a generation in a pool than is not suitable. if the pool is running fie then leave them to come along in time. you might go a season with no spawn but you will still have all the other invertebrate and possible vertebrate life to enjoy.

[eeyore]

Originally Posted by Deb London

There is some very interesting information in the 'big thaw' site that eeyore highlighted recently.

The findings seemed to suggest that there are a few things to be done, or at least to be designed into any new pond.

Correct me if I'm wrong people.

Things that may help:
Having a shallower pond of around 30 cm (contrary to previous advice which called for deeper ponds and very interesting from my point of view as I have always tried to create very deep ponds*).
Possibly keeping snow off the surface and possibly running a pump.
Having plenty of oxygenators.
Blanket weed and algae!

Things that don't/aren't thought to help:
Making a hole in the ice, any which way it might be done.
Having too many leaves and too much sediment on the bottom of the pond.

The answer to why frogs die probably involves the amount of available dissolved oxygen and might involve the build up of toxic gases. There is plenty more research yet to be done.

[*That said, three frogs were recovered when I emptied my large pond this winter to do essential maintenance. All three were living. I do have plants and the very bottom. There are some young water lilly and Aponogeton shoots that might have been photosynthesizing, possibly some Hornwort near the bottom, and an abundance of Water Soldier, which sinks in winter. I'm wondering if the latter might have been a godsend.]

not entirely so deb

certainly shallow water and margins are a good idea but a very shallow pond will freeze solid in prolonged sub zero temps so it is still a good idea to have a deep water element (frogs in torpor can survive being frozen but it is lethal for much aquatic life such as dragonfly larvae.)

Keeping snow off the ice definitely helps because it allows light to reach the oxygenating plants thus enabling them to photosynthesise

and with regard to the hole in the ice - while it is true that it wont do much to improve oxygen levels as oxygen is only diffused into the water very slowly at the surface, it is a good idea to maintain a hole by melting with hot water (not by breaking or by chemical) because peircing the ice imn this way allow noxious gasses from anaerobic decomposition to escape rather than becoming concentrated under the ice - which is bad for both amphbians and aquatic life

[Deb London]

Ah, cheers Pete, lots of food for thought there.

[animartco]

Originally Posted by Dogghound

This is correct at the very base of the scale, with most species. It is more often seen in plants and invertebrates. Dormice dont exhibit massive difference in biology in different parts of Britain other than time of hibernation etc and possibly other slight differences. Not to the extent of one changing its entire hibernation stratergy which has evolved over its history, just because its in a different county. Again amphibians and reptiles are the same they behave in the same way, just climate may alter hibernation times in the UK. If you were describing the differences in behaviour between a smooth newt in Norway or one in southern greece I could then understand it, but not British dormice.



Actually this is as far away from the truth as you could get. Without disturbance dormouse would probably be extinct. They require coppiced woodland. This creates huge amounts of disturbance but the end product is a perfect habitat. The middle stages of hazel growth are of particular importance to dormice, this is often when the canopy is quite thick. This disturbance encourages hazel to spread, it also allows a thicker herb layer and a more diverse structure of plants/trees to emerge. Disturbance in winter can be a problem to dormice, however this is no different from in a wooded garden.



Dormice which I have explained have specific hibernation requirements. Woodland or thick hedgerows. If the shrubbery is hazel or close to hazel then it may be of value. However grassland is not necessary for this species. The only other species which hibernate are bats which it is of no value, hedgehogs and edible dormice which may use it. Although the structure of the shubbery would dictate how useful it is to both of these species (particularly edible dormice). No other small mammals hibernate in Britain! And UNTRODDEN grass is of no significance.

Untrodden grass is the commonest of all hibernation sites. Perhaps just because suitable spaces beneath tree roots are not THAT easily found, and I do of course agree that things WILL hibernate in man made hibernaculums, although only under protest. Animals are not silly. They are looking for a place that will NOT be disturbed and anything newly constructed will be suspect. But the Favourite place is beneath a tussock of rough grass, at the side of a hedgerow or wood or along a 'ride'. Dormice NEED this because of the way they construct their nests. They like them perfectly round, and in a tussock they can create the right shape, by chewing out the centre until they have a little dimple in the ground, as if you pressed a pingpong ball into it. They then line the hole with moss, and then bring in the strongest widest blades they can find and wind them neatly round themselves. Then they go to sleep. How do I know this? Because I examined the nest of the dormouse I killed. and it was far too neat to have been the work of a 'maverick'.

[eeyore]

Originally Posted by animartco

Untrodden grass is the commonest of all hibernation sites. Perhaps just because suitable spaces beneath tree roots are not THAT easily found, and I do of course agree that things WILL hibernate in man made hibernaculums, although only under protest. Animals are not silly. They are looking for a place that will NOT be disturbed and anything newly constructed will be suspect. But the Favourite place is beneath a tussock of rough grass, at the side of a hedgerow or wood or along a 'ride'. Dormice NEED this because of the way they construct their nests. They like them perfectly round, and in a tussock they can create the right shape, by chewing out the centre until they have a little dimple in the ground, as if you pressed a pingpong ball into it. They then line the hole with moss, and then bring in the strongest widest blades they can find and wind them neatly round themselves. Then they go to sleep. How do I know this? Because I examined the nest of the dormouse I killed. and it was far too neat to have been the work of a 'maverick'.

Dormice are arboreal - they live (and hibernate) in trees, usually hazel - they do not make perfectly round nests(or indeed any other shape) in grass tussocks - you are, as dogghound suspected earlier describing a harvest mouse nest.

Thats the last you'll hear from me as I really dont know why we bother and you are going on my ignore list from now on so my wab experience isnt poluted by your fanciful and ill informed nonsense

[Farplace]

Originally Posted by animartco

Untrodden grass is the commonest of all hibernation sites. Perhaps just because suitable spaces beneath tree roots are not THAT easily found, and I do of course agree that things WILL hibernate in man made hibernaculums, although only under protest. Animals are not silly. They are looking for a place that will NOT be disturbed and anything newly constructed will be suspect. But the Favourite place is beneath a tussock of rough grass, at the side of a hedgerow or wood or along a 'ride'. Dormice NEED this because of the way they construct their nests. They like them perfectly round, and in a tussock they can create the right shape, by chewing out the centre until they have a little dimple in the ground, as if you pressed a pingpong ball into it. They then line the hole with moss, and then bring in the strongest widest blades they can find and wind them neatly round themselves. Then they go to sleep. How do I know this? Because I examined the nest of the dormouse I killed. and it was far too neat to have been the work of a 'maverick'.

Dormice hibernate in bushes, not in grass. It couldnt have been a dormouse.

[Malcolm Banks]

Not sure I've been reading the right PC Big Pond Thaw report of 2010 since from the version I read it does appear the jury is still out on the issues of holes/toxic gases and snow clearance. On the holes issue, to quote the report "The results showed that making a hole in the ice didn’t make any difference to the likelihood of mortalities."
On the snow clearance "Detailed studies of one of our garden ponds showed that a blanket of snow can seriously reduce oxygen levels, and snow clearance can reverse this. However, across the survey as a whole, clearing snow did not appear to affect the likelihood of amphibian deaths."

In mitigation they do suggest that more work needs to be done/data gathered on both issues, in particular the impact of oxygenating plant type and density.

The PC Big Thaw report may not be the only source so if people have other data I should be grateful for a source ref.

I think the PC people are doing a great job collecting the data and along with others have debunked several urban myths in the last year or so. By replacing urban myths with evidence-based strategies for pond design and management, all our ponds and their environs may benefit,.

Oh, and I totally agree with Tom00 that if you want to facilitate the spread of chytrid fungus and ranavirus (not even mentionng the killer shrimp) then encourage spawn exchange. That is not to say that it should never happen, but should be very carefully controlled.
M