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Frog tadpoles not reaching maturity...: |
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DavidP Member Joined: 02 Mar 2007 No. of posts: 4  View other posts by DavidP |
Posted: 12 Aug 2009 Had breeding colonies of common frogs in my garden pond for years, have been very successful, with plenty of small froglets hopping around. Last 2-3 years though, have noticed a trend of frogs laying spawn, eggs hatching.. tadpoles lasting several weeks.. then nothing, completely dissapearing before they get legs. My concern is that this has happened for at least 2 years, probably 3. The adult frogs still seem happy enough, but where before we had a few generations of frogs, now there arent any younger ones keeping the colony going. This year I took a small number of eggs and put them in a fishtank, to see how they got on.. same thing, all dissapeared. I've seen this issue raised on other forums, but never an explanation or cause. Also heard of similar stories from friends with ponds. We live in south west london. Any clues/ideas ?
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Suzi Senior Member Joined: 06 Apr 2005 No. of posts: 860 View other posts by Suzi |
Posted: 12 Aug 2009 I have the same thing happen in my garden. The first spring of having my pond I put in some newly hatched taddies from my neighbours pond. I had a high number turned to froglets and get away. The following few years none made it past taddie stage. This year I had my own frogs spawn in my pond and make it to the stage of wriggling out of the jelly and then overnight all disappeared. In late May this year I saw an introduction of what must have been thousands of toad tadpoles into a largeish garden pond. By the next day not a one was left! I have seen water boatmen (is it?) gobble them up and garden ponds often have a lot of these vicious blighters. Then there are dragonfly nymphs (not present the first year of ponds). I also have newts in my pond. I am really not sure what the answer is but I do think garden ponds are too small and cosy for some of these tadpole/spawn predators. I have kind of accepted that whilst I have plenty of frogs (from small to large) my pond will not be a successful nursery for frogs. I have considered removing spawn and raising it in a separate container but care is needed that the water doesn't overheat in the sun and kill everything. Suz |
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DavidP Member Joined: 02 Mar 2007 No. of posts: 4 View other posts by DavidP |
Posted: 12 Aug 2009 not sure it is predators, dont really see much wildflife beyond frogs and pond skaters and the occasional dragon fly. Not seen any newts or boatman. The concern is that we go from several hundred tadpoles, most up to an inch and a half long, looking as though legs are imminent.. to none, in a matter of days. As I say, this has happened at least a couple of years running.
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lalchitri Senior Member Joined: 06 Jun 2006 No. of posts: 132  View other posts by lalchitri |
Posted: 28 Aug 2009 Based on my own observations, I've put my reasons for tadpole death into 4 categories 1. Temperature - At the spawn stage and during early tadpole life, a frost or exceptionly cold snap causing the pond to freeze over can lead to major disaster for the tadpoles. Conversely, during a hot spell earlier this 'summer', when temperatures in the south topped 30c for over a week, I found many dead tadpoles floating at the surface of the pond - something I observed only during that period 2. Lack of food - Guess can be a problem in a newly established pond, but then those that do die are quickly eaten by the survivors. 3. Quality of water - Plenty of water plants and vegetation will help negate this. In the first year of my pond, there was not much food, so I fed them fish pellets. Not all of this was eaten, and on a hot week-end caused the water to pollute and killed almost all of my tadpoles. 4. Predators - newts, water-boatmen, dragonfly nymphs etc. I've regularly seen crows this year, standing at the pond edge for long periods of time, poking around at the water's edge. Difficult to prevent and, unless you want a frog only pond, rather dull. Ponds will always be inhabited by many species who will feed off each other as part of the food chain. Reformed Teetotaller |
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herpetologic2 Senior Member Joined: 15 Jun 2004 No. of posts: 1369  View other posts by herpetologic2 |
Posted: 29 Aug 2009 Frogs do breed well in garden ponds for a few years but then their success is very much reduced for the reasons Lalchitri has stated. My frogs in my old pond bred well the first season, I then noticed that the tadpoles did not develop as fast as they did the first year and there was tadpole predators - newts etc I ripped out the vegetation from the pond to create warm sunny pools where the next year the tadpoles hatched and they tended to shoal in the shallow water in a large mass which provided protection from the 'predators' (I suspected) The tadpoles developed well and they did manage to metamorphose - so can this be applied to your situation? J Vice Chair of ARG UK - self employed consultant - visit ARG UK & Alresford Wildlife |
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ben rigsby Senior Member Joined: 27 Apr 2010 No. of posts: 337 View other posts by ben rigsby |
Posted: 27 May 2010 just to add to lalchitris cause of death list, OVERCROWDING can lead to a sudden die-off. im sure thats the reason i lost everything in one of my pools this year. there was so much spawn you could barely see the shallow water. as jelly rotted post-hatch it (like lal's fish food), rotted and polluted the environs. no survivors. an oily film remained on the surface for days afterwards. another reason for taddie armaggeddon could be disease? Diversity. |
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Suzi Senior Member Joined: 06 Apr 2005 No. of posts: 860 View other posts by Suzi |
Posted: 27 May 2010 As mentioned on another thread I removed all my spawn from the pond as soon as it was laid this year. I put it in various buckets in a cold greenhouse. As it was early in the year the greenhouse didn't get hot (I opened all the windows every day to keep it even cooler) and the taddies soon hatched. After a while I put them all in a very large plastic box with weed and duckweed. They had done very well and some were getting first legs but when we got this very hot spell it was obvious that the water was getting overhot and deoxygenated. I was on the point of moving them out of this container when I lost about 100 in a day, so I was cross about that as it was my own fault. Anyway I transferred about 150 to my garden pond and they are doing well. They are beefy enough to survive the predators I think. My neighbour has frogs lay in her pond and the taddies shoal in the shallows but newts still get them and water boatmen and birds (blackbirds love them). I would not have raised one frog from these if I'd left them in the pond - I know from past years. Frogs lay a lot to lose a lot but I'd rather intervene and get a few more to froglet stage. After that they're on their own! Suz |
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lalchitri Senior Member Joined: 06 Jun 2006 No. of posts: 132 View other posts by lalchitri |
Posted: 28 May 2010 I also keep some of the spawn in a container every year. They can go well for weeks but all of a sudden a few dozen will die. The dead pollute the water more (try emptying the container and smelling the bottom portion with all the sunken dead tadpoles), which causes more to die. As soon as I see more than a couple of deaths, I empty out the containers, catching the tadpoles in a fine sieve, and refill the container with fresh water left out in the sun for a couple of days in a bucket and returning the tads caught in the sieve. Reformed Teetotaller |
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ben rigsby Senior Member Joined: 27 Apr 2010 No. of posts: 337 View other posts by ben rigsby |
Posted: 28 May 2010 it seems im not alone in my interventionalism (is that a word?) in transferring some tadpoles elsewhere to give them a fighting chance of survival then! suze - sorry to hear of your tad problems but, in your conclusion, YOU SPOKE MY MIND. i know all too well lal's findings. hope the reformed teetotaller drinks real ale. like a proper man does. 
ben Diversity. |
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ben rigsby Senior Member Joined: 27 Apr 2010 No. of posts: 337 View other posts by ben rigsby |
Posted: 15 Oct 2010 up to about 3 weeks ago i still had about 15 (at a guess) common frog tadpoles yet to sprout limbs. now, IF still alive alive-oh, they have all gone into hiding. no sign of em. interestingly, they all disappeared at the same time. no frosts here yet. anybody got legless or otherwise late developers still active? do tadpoles have to have reached a certain stage of metamorphosis before overwintering becomes viable or doesnt it matter? more developed individuals seem more robust to me somehow but legless ones have used up less of the reserves later exploited for limb growth by reabsorption of the tail. maybe that helps see them through better and puts them in a stronger position in early spring???? info/opinions/corrections please! happy herping (while we still can!) ben Diversity. |
- Frog tadpoles not reaching maturity... |