Dead frogs

by Kate Bradbury

This week at we've received lots of letters, emails and blog comments from people who have found dead frogs in their pond.

Rescue frog, photo courtesy Julie WatsonThis week at we've received lots of letters, emails and blog comments from people who have found dead frogs in their pond. I've not seen my rescue frogs since October – I'm hoping they’re tucked up safely in the compost bin. But others haven’t been so lucky.

I asked Jules Howard at Amphibian and Reptile Conservation (ARC) what was going on. He explained that because male frogs often lie dormant at the bottom of ponds during winter, they’re prone to dying when the ponds freeze over. This phenomenon - called 'winterkill' - is relatively common, but has been more prevalent this year due to the length and severity of the freezing weather.

Frogs slow down their metabolism when lying dormant, and breathe through their skin. They can survive if the pond freezes over - especially in ponds with lots of plants growing in them, as plants can still photosynthesise under ice and produce oxygen. But if there aren't sufficient oxygenating plants growing in the pond, if it contains lots of leaf litter (which releases noxious gases as it breaks down), or if snow covers the pond and prevents the plants from photosynthesising, gases can build up in the pond and kill the frogs.

ARC suggests doing the following: make a hole in the ice by leaving a pan of hot water on the surface, allowing the base of the pan to melt a hole. Then leave a plastic ball in the hole overnight, and remove it the following morning when the pond surface has refrozen. This enables noxious gases to leave the pond. ARC also warns against smashing, or pouring hot water on the ice, or adding chemicals (particularly salt). All of these methods can cause serious damage to pond life.

Sadly this is all too late for many of our frogs. But now the ice has melted, give your pond a bit of an MOT: clear away leaf litter and invest in some plants to help keep your pond healthy for your frogs, toads and other pond life.

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Gardeners' World Web User 27/01/2010 at 11:49

I have not seen any frogs in my garden yet but they must be alive and well as the heron who visits from nearby countryside is arriving every morning to hunt for them. They have to move for him to spot them. Sometimes they wriggle and escape and i have three-legged frogs hopping about the garden.

Gardeners' World Web User 28/01/2010 at 19:09

I haven't seen any dead frogs in our newish wildlife pond but suspect there may be. We have however lost all 4 huge Koi carp that we've had for about 10 years. We've had them since they were very small. One was left in the pond when the previous rsidents left. He was only about one and a half inches long and we bought 3 others to keep him company. They have happily survived 10 winters with a floating polystyrene gadget to keep an area clear of ice and allow the exchange of stale and fresh air. While not exactly wildlife, we were gutted. One of them even remembered from year to year how to bang the automatic feeder to obtain food! So much for fish having a short memory!

Gardeners' World Web User 28/01/2010 at 19:30

I have fished out three dead frogs one adult and two young, which is quite worrying, I have also lost five fish of various sizes.

Gardeners' World Web User 28/01/2010 at 20:01

I am now living in Holland, and this year when the ice on the canals melted, the canals were littered with floating dead fish and frogs. A great shock to most people as we have had frozen canals often. Strangely enough the ice this year never got thick enough to host the intercity skating marathons on the canals, but for some reason was bad enough for the fish to die.

Gardeners' World Web User 29/01/2010 at 09:36

I couldn't buy a ball when the harsh weather came, so I used a plastic bottle with a little water in. It worked a treat.

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