Effects of the big freeze on ponds

Sadly, as you’ll have seen from the comments, there are beginning to be reports of dead frogs now that ponds are thawing.

UPDATE: And newts to.

This also happened last year in the shorter freeze we had in January 2009 (see this post, for example, and especially the comments that follow it).

I’ll be posting more about this over the next day or two, and doing my best to answer questions, so keep an eye on the blog.

In a special extension of The Big Pond Dip survey, we at Pond Conservation will also be seeking your help to tell us more about what happened to your pond during the freeze.

Given that we know so little about what makes ponds tick, both in the garden and in the countryside, this information will help us improve pond design and management in the future.

I should say, for those who expected the Big Pond Dip results to be available by now, they are coming soon – but we’ve been focusing on the more urgent icy pond information first!


7 Responses to “Effects of the big freeze on ponds”

  1. ocksblog Says:

    just found you site after searching to see if I should have broken the ice on my pond.
    It’s tiny, smaller than a bathtub, but has always been popular with frogs.
    I didn’t break the ice for a long time this winter, until a few days ago. When I broke it i found two dead frogs at the surface.
    More of the ice has melted since and I’ve jsut been down there and found another 13 dead frogs. Plus one goldfish.

    I’m really sad about this, they are my favourite animal, and in fact I’ve had dreams about going to my pond and finding all the frogs dead or mutated, so it was quite an odd experience.

    I hope the species hasn’t been hit too hard as a whole

  2. pondlovingScot Says:

    I have a self-made 15 year old established and thriving wildlife pond in Stirling, Scotland which has a good balance. 4 metres x 3 metres x 1 metre deep and no filtration. At the outset I introduced 3 small golden orfe and various plants (marginals and pond plants). Apart from summer feeding and the occasional tidy, the pond is virtually maintenance free. I have never had to top up water levels. The fish have grown to almost a foot and in recent years various offspring have appeared. It freezes over every winter and I have never taken any precautions and the fish have always survived. It has been frozen over for 5 weeks now and the ice is pretty thick (probably thicker than ever before). This afternoon I noticed the 3 large fish had died (I can see them floating under the ice). This prompted me to check online for advice and I found your site. I’m going out now to melt the ice carefully in the hope that some of the smaller inhabitants have survived. I have learned a very harsh lesson and I feel really sad for the fish.

  3. pondlovingScot Says:

    I have melted holes in the ice using pots of boiling water and the dead fish have been removed. The good news is I have seen several smaller fish still darting around. I have learnt a very harsh lesson and in future I will be keeping a very close eye on the pond in winter.

  4. Sally Says:

    I noticed your posts about frogs freezing in ponds. I also had four dead frogs this year, but it is because I had netting over the pond. The part of the pond that the frogs died in was too shallow for them, and because of the netting they could not get out. In the larger pool, which is 3 1/2 feet deep, I always install a floating heater, which is just warm enough to keep a small hole open in the ice. You can find these heaters on line or in any pond supply store in the US. Of course, you have to have electrical nearby, but perhaps there would be as solar powered one available? Keeping a hole open allows an exchange of gasses, getting rid of bad gases and letting oxygen in. I am documenting the life cycle of my pond with many photos on my blog if you would like to visit! Good luck to everyone with their ponds this year. πŸ™‚

  5. Yvonne Bignell Says:


    so far we have had a nil mortality rate (frogs and fish). We built a corragated temporary cover over one small area of the pond and kept the water gently airated. This left a thawed area throughout the worst part of the freeze (ice 4 inches thick). Then we put the small winter filter on with the pump at a high level and the inflow pipe under the water/ice just to prevent further freezing as we came out of the freeze with still frosty nights.

    Our problem is with too many frogs, last year we had to relocate over 90 frogs because the pond could not cope. This year, so far we have relocated approx 50.

  6. Anne Elizabeth Fox Says:

    We have a small garden pond approximately 6ft x 3ft. This year we have so much frog spawn and far too many frogs. Do you have any advice as to where we could take them and give them a better chance of survival?

    • Jeremy Biggs Says:

      Dear Anne

      I don’t think there’s any need to move the frogs away, and you don’t need to worry that you have too much spawn.

      I owuld guess the most likely reason you’ve got lots of frogs is that your garden, and the area around it, is a good habitat for frogs capable of supporting reasonable numbers of the animals. You may also have had a series of good breeding years allowing populations to build up. Frogs have population ups and downs so this situation may not last.

      Once spawning is over most of these frogs will melt back into the surroundings to live out their lives on (fairly) dry land. So I’d see it as sign of success that you’ve got so many.

      With lots of frogs this does mean that in some years you get a lot of spawn and one naturally starts wondering ‘is this going to overwelm the pond, and should I move some away?’

      But there’s a couple of reasons why this is probably not a good idea.

      First of all our common frog is a ‘boom and bust’ animal that has evolved to produce large numbers of eggs many of which are destined not to reach adulthood. So although it feels like the right thing to be doing – to move some of the spawn so more of it may develop to adulthood – it probably won’t make all that much difference to the total number of survivors.

      Also moving them to a pond without spawn might simply be moving them to somewhere that’s an unsuitable habitat. Frogs are pretty widely distributed and if there’s no spawn in a pond it may be because it’s not suitable or the local frogs haven’t found it yet. In our detailed look at Abingdon garden ponds practically every pond has visting frogs but not all have them breeding. So frogs are getting pretty much everywhere but not using all the ponds to breed.

      Also, and perhaps more important, moving spawn about may increase the risk of spreading amphibian diseases and non native plants. This advice is part of a growing general worry about amphibian diseases but at present no-one really knows quite how big a threat diseases are to our amphibians. The worry is that moving spawn might make things worse – although very short distance movements (within the same garden, to a very near neighbour say within 100m, the distance that frogs could easily move themselves) seem unlkely to do much harm. To give you some feel for this, amphibian biologists are imposing on themselves very strict rules about avoiding the spread of diseases although it’s probable that people professionally involved in amphibian surveys, who may be visiting lots of ponds over quite big areas, are actually more in danger of spreading things than garden pond owners. We simply don’t know for sure.

      So I think you’d be best to just let nature take its course.

      I wonder if there’s any chance of having a second pond to provide additional breeding habitat for your frogs?


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