Written by Jade Walton, Transforming Lives Trainee
As the weather gets colder, it becomes increasingly likely your garden wildlife pond will freeze over. Though at first thought this may not seem like much of an issue, this can be dangerous for the wildlife beneath the surface.
Whilst newts and toads tend to find other places to brumate (a process akin to hibernation), some frogs will choose to overwinter amongst the silt at the bottom of a pond. In regular conditions, this poses no threat to the frog, but should the pond freeze over for a prolonged period, it can become deadly.
It is thought the death of frogs overwintering in ponds is likely caused by a lack of oxygen in the water as sunlight is unable to reach plants and algae, making them unable to photosynthesise and oxygenate the water. Another theory is that gases are expelled by dead plant matter within the pond as it decomposes which are blocked from escaping into the air via the surface of the water. This may lead to a deadly build up of these toxic gases, causing ‘winterkill.
There are some ways, however, that you can minimise the risk of winterkill in your own pond. Make sure to brush any snow from the surface of your pond to give sunlight the chance to hit the ice. It is also thought to be a good idea to ensure there is always a hole in the ice to ensure gases can escape. This can be done by floating a tennis ball in your pond, preventing it from icing over fully, or by putting a container of hot water upon the ice to melt a hole in it.
It is not good practice to create a hole in the ice by force as the physical shock can harm the wildlife beneath, also be sure not to use chemicals or pour hot water directly onto the ice as this too can have a harmful impact on pond wildlife. And, of course, be sure that, when conducting these preventative measures, you do this in a safe, controlled manner.
With your help, the risk of winterkill in amphibians can likely be reduced in just a couple of steps.
Find more tips on what you can do for amphibians and reptiles this winter here.
The next step, once the pond is dug, is to use the appropriate liner. This could be made of rubber, clay, PVC, or you could use a preformed pond made of plastic or fibreglass. To fill your lined pond you could either wait for it to fill naturally with rain over the winter months, or use appropriately treated tap water.
There has been a 50% decline in pond habitats in the UK over the past century, with 80% of those remaining being classified as either in ‘poor’ or ‘very poor’ condition. We can all do our bit to tackle this problem.
Here at Froglife we love our four-legged companions and know how important daily exercise is for our beloved dogs. While there is no harm in letting your dog swim in many different bodies of water, it is highly encouraged to steer them clear of ponds, especially during amphibian breeding season, and here are some reasons why: 
