Winter Frosts

At Wicor Primary School we are encouraged to go outside in all types of weather, so for us a week of hard ground frosts (when the temperature of the ground falls below freezing point 0ºC/32ºF).

The cold weather has not stopped us from observing our grounds and finding out what happens to some of the animals in it, although the frosts do not seem to have bothered the triceratops in our Jurassic bed.  

It has certainly been very beautiful in the mornings, with many of the plants looking like they are wearing jewellery.  We have lots of grassy habitats at Wicor and although frost does not damage the grass, we found out that pressure on frozen grass causes the leaves to fracture and then ruptured cells can seriously damage it.  Knowing this it is amazing that our grass survives seeing as it has hundreds of feet stampeding on it every day!  We also compared a holly leaf to a frozen one under the microscope to try and see the differences.

Our pond has frozen over twice in the last week and in the past we have broken the ice thinking this would help.  However, new research by the conservation charity ‘Pond Conservation’ has shown that most wildlife in garden ponds will survive a pond freezing over if it is left alone.  Apparently, breaking a hole in the ice makes very little difference to the oxygen levels in the water and plants will also carry on photosynthesising under the ice.  We have therefore decided to just net the leaves this winter to stop them falling into the pond and turning into silt – this is a mucky job and so there are plenty of volunteers.

During the rest of the year, we regularly dip in the pond to see what is living in there, so we know we have long bodied dragonfly nymphs, smooth newts ‘Lissotriton vulgaris’, stags horn snails, common toads ‘Bufo bufo’ and common frogs ‘Rana temporaria’, as well as pond skaters and water beetles.  Damselflies are also regular visitors. 

So this week we decided to investigate further and find out what happens to the frogs in our pond over winter.

Apparently, all frogs and newts (amphibians) in the UK must hibernate to survive the winter and frogs do this by lying dormant in compost heaps, leaf litter, underground tunnels or log piles.  So we have provided lots of winter habitats around the pond for our frogs including log piles all stuffed with fallen leaves.  There is also a large bug hotel made of pallets which they might like to overwinter in, and two small decking areas, where we sit and sketch, that provide additional shelter.   All of these areas let the frogs hide from predators and enter hibernation.  This is when their body functions slow down to a minimum and their bodies freeze.  Most creatures cannot survive this so the frog is the greatest toughie!  Sometimes frogs will prefer to overwinter in the bottom of the pond, where they will bury themselves in mud, and the temperature is slightly warmer.  They will be fine there unless the pond freezes over for a long period of time.  As ours has only been frozen for four to five hours at a time we think the frogs will be fine.

We were surprised to find out that frogs might even come out of dormancy to forage in milder periods of weather, so we will be on the lookout for that in the next few weeks.

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