Oh dear…the first frozen frogs

The frogs were found dead beneath the ice of an Oxford garden pond

Sadly we’ve received the first pictures of frozen frogs – well, actually probably frogs that have run out of oxygen.

This photo comes from Norma Smith who works in Oxford Brookes University – and interestingly she reports that in the  last four years (including the very severe 2009 winter), she saw no dead amphibians when her pond froze over.

So what’s the cause here: it could indeed be lack of oxygen, but maybe these frogs have succumbed to something else – perhaps simply old age?

We’ve little idea what the effect of the cold weather was last year on our Common Frogs, or any other water creatures for that matter.

Certainly, in our garden, 2010 was a bumper year for frogs – and I didn’t hear anyone suggest they had a shortage this year.

It would be interesting to hear the views of others on this.


12 Responses to “Oh dear…the first frozen frogs”

  1. jonspond Says:

    It would be good to sample these frogs for rana virus the Institute of Zoology may want to test these dead frogs for the presence of this virus.

    I wanted to post a development in the Killer Shrimp story

  2. The big pond thaw survey 2011 « Pond at 38 Nursery Rd Blog Says:

    […] The first frozen frogs have been reported through this last round of snowy weather http://thegardenpondblog.org.uk/2010/11/30/oh-dear-the-first-frozen-frogs/ […]

  3. mrnatural Says:

    I have a plant tub about 2ft x 2ft which is filled with water and has an iris in it. It’s regularly home to a frog or two. Last year in the freeze I neglected to clear the ice and sadly upon thawing the resident frog was found dead. In this cold snap I forgot again to check the tub. Today I could see under the 3/4 inch ice what appeared to be another dead frog, body about 2 inch long. I managed to slowly melt a hole in the ice and remove the lifeless body, which also had blisters on the toes.
    It appeared dead, but on my hand in the house just now it has very slowly come back to life. What to do?
    It is very floppy, not at all lively. One suggestion from Amphibian Reptile Conservation was to place it in a bucket with a little water in the house as it recovers overnight, then place the bucket outside tomorrow to acclimatise before returning it to the tub.
    Any other suggestions?
    It is currently sat in a bucket with a little water, improving by the minute.

    • Jeremy Biggs Says:

      I think the suggestions from Amphibian and Reptile Conservation are sensible and the best thing to do. If the frog doesn’t pull through though, remember it could have been getting on a bit anyway – frogs don’t live all that long – or simply run out of fat reserves.

      One thing: if you return it to the tub, probably worth making sue that ice on the tub is not snow covered so algae and any plants under the water can go on producing oxygen.


  4. Stefan Drew Says:

    2010 – A bad year for frogs!

    For the first time in the last eight years, when we built our ponds, we had no spawn and no sign of adult frogs in our ponds this year.

    Counts normally go into the 30-40’s but this year we had just a handful of half grown frogs in the late summer.

    Any thoughts why?

  5. jonspond Says:

    There are a variety of reasons why the frogs appear to have crashed in numbers – old age, the cold winter, to even the ponds becoming unsuitable for the frogs – do you have fish? how big are the ponds size & depth? and do you actively manage the ponds in the winter?

    The frogs you have been seeing each year may have come to the end of their lifespan and so without good recruitment from your ponds this has left only a few animals which are not mature enough to breed yet

    Amphibian populations do go up and down in numbers naturally – the presence of fish and other predators in combination with cool weedy water could also affect recruitment which would then have a knock on effect on returning amphibians

  6. Stefan Drew Says:

    Thanks for your reply.

    We’ve had spawn every year until this year so I’d be surprised if it is old age. We don’t have fish so it isn’t that.

    One pond is 4ft deep and measures 12*6ft The other goes down to 3.5 ft and is approx 15*10 ft. I’ve always built ponds with plenty of depth as shallow pools can freeze solid. Both have good populations of plantlife, newts, (hence no fish) dragon flies etc.

    We do little winter management except remove the worse of the windblown leaves in autumn. Water quality is generally reasonable with no blanket weed or green water in the spring.

  7. jonspond Says:

    I would hazard a guess that the frogs have not been recruiting for the last 4 years from the ponds – due to the depth of the water (too cold for rapid development of tadpoles) & predators (newts & dragonflies) which would reduce the numbers getting to metamorphosis

    I remember an assessment of a newt population in around 2004 which failed to recruit in that year was predicted to have a crash in three years after that assessment.

    I suspect that the same could be said for the frogs in your ponds. One way to test this is to provide another pond which is more like the ponds which Jeremy has dug in this blog.

    I have a small pond which is approx 1metre in diameter and is only 20cm deep with the majority of the pond being 5cm or less – perfect conditions for frogs to lay their spawn and for it to hatch and develop quickly.

    Frogs are adapted for breeding in small shallow pools – hence the name Rana temporaria – means ‘temporary’ frog as it bred in shallow pools found in woodland and meadows – it seems that these warm water bodies are what the frog needs to beat the predators which build up in more permanent ponds –

    Frogs avoid laying spawn in newt ponds especially great crested newts which are an avid predator of frog spawn and tadpoles

    The flip side is that toads can do well in large open water bodies for the opposite reason – they need good oxygen levels, can withstand predator pressure due to the tadpoles having toxins in their skin and especially in open water where the main predator is fish – in weedy conditions predators such as dragonfly larvae can capture the tadpoles and pierce through the toxic skin reducing tadpole numbers and again recruitment – which may also lead to population crashes

    When the habitat is more favourable then the population can pick up again.

  8. jonspond Says:

    PS my small pond has not frozen solid despite the cold temperatures (-7) and snow fall

  9. jonspond Says:

    See previous posts on here

  10. Stefan Drew Says:

    So too big and too deep are a bad thing. Colder water would make sense as do the newts.

    The larger pond does have a shelving “beach” one side which would be warmer and where most tadpoles congregate.

    The newts and frogs seem to have coexisted for some years and there are a lot of other ponds in local gardens .. some with fish some without.

    We also have grass snakes .. which would not help!

  11. jonspond Says:

    Its not the grass snakes which you should be worried about – it is the predators which can pick off the tadpoles and metamorph froglets – this is key in reducing adult numbers overall

    Warm water which is shallow will provide the best conditions for the tadpoles to grow beyond the size that they can be eaten by newts for example – shallow areas also allow protective behaviour from predators – grouping together would protect the majority of the tadpole population from newts – safety in numbers the taddies on the inside of the group are protected by the tadpoles around the edge.

    The coexistence between the two species would have been fine until fewer frogs were making it to maturity for breeding – with the adverse weather we have had this may have tipped the balance

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