In the depths of winter

“Today we woke up to a revolution of snow,   

its white flag waving over everything,

the landscape vanished,

—- under the noiseless drift” (Snow Day by Billy Collins)

A Very Happy New Year from the Muir of Dinnet NNR team.

For the past six weeks the reserve has been in the hard grip of winter and transformed under the silent influence of snow and ice. Whilst a snow blanketed landscape is spell binding and spectacular it can be a challenging environment for wildlife.

Morven in the depths of winter

The UK gets on average 23.7 days of snowfall or sleet a year.  In Scotland, the figure is much higher, with snow or sleet falling on 38.1 days on average. Statistically, the snowiest place in the UK is the Cairngorms in Scotland, with 76.2 days of snow or sleet falling on average.

At it’s height we had 17 cm of snow accumulated on the reserve, transforming everyday sights into wonderfully alien landscapes.

A frozen Loch Davan

In between times we have had days where milder temperatures have broken up the ice sheets. Open leads snake through the most amazing ice floes and the sound of ice breaking up and lapping the shoreline sounds like a thousand tinkling wind chimes.

The dark nights also have their own beauty – and the reserve can look magical under starry skies.

A starry starry night over Loch Kinord
The Vat looking dramatic under night skies
Red grouse have been forced down from the hills and can be found sheltering in the gorse thickets around loch Kinord right now

Winter brings very different challenges to our wildlife – temperatures are lower, days are shorter and food is harder to find. Winter requires survival strategies!

Mammals like foxes, pine marten and badgers grow a thicker coat to help keep them warm.

For Badgers, a thicker coat changes the shape of the animal. The Badgers begin to look much more ‘barrel’ like in shape.

And some, of course, hibernate! We often think of hibernation as the number one solution – how great would it be to eat as much as possible and then just sleep until it gets warm again?

A young hedgehog – in hibernation now for a couple of months

Hibernation is, in reality, far more than just a long, deep sleep in a quiet burrow or cave. Only two of the animals on the reserve truly hibernate; bats and hedgehogs, and the process is a little more complex than you might think!

Pipistrelle bat. Bats hunt for hollow trees, roofs, caves and bat boxes to spend their winter months. They usually hibernate from November to April. To help get them through this period, bats can slow their breathing to as few as five breaths a minute. Some species can last almost an hour without breathing at all!

Hibernation is a prolonged period of inactivity that allows animals to survive when food is scarce and the weather is harsh. Typically, the animal will first build up a reserve of body fat by eating as much as possible in the lead up to winter.

They will then retreat to somewhere safe, where they will enter a torpid state. This is where almost all of the animal’s bodily functions are either completely halted or are slowed down significantly. This reduces the amount of energy the animal’s body has to burn to survive. Its body temperature will cool, and its breathing and heart rate will slow down.

While such a deep torpid state might seem like it leaves them vulnerable, it actually makes the animal very difficult for predators to detect as they give off less of a scent, hardly move, and make no sound while hibernating.

Another way in which hibernation differs from normal sleep comes when it is time to wake up. We all know how difficult it can be to get out of bed on cold winter mornings, but hibernating animals often take up to an hour to fully awaken from their torpid state.

Animals may wake up several times during the hibernation period to go to the toilet, move locations or, occasionally, have a little snack.

Badgers and red squirrels do not hibernate, but they do enter a state of torpor. Unlike hibernation, torpor is involuntary, and animals only enter it when environmental conditions become too harsh. It doesn’t last as long as hibernation and animals may come in and out of this state more easily than true hibernation.

What about all the other animals that disappear over winter? Reptiles, amphibians, and many insects all seem to vanish as the weather turns cold. Whilst they don’t truly hibernate, they do rely on different strategies to see them through until spring.

Our reptiles and amphibians are all in a period of dormancy known as Brumation. It is very similar to hibernation in that it is characterised by extended periods of very minimal activity to save energy. As animals that rely on the temperature of their environment, as it gets colder, reptiles like adders become more lethargic and less able to hunt.

One of last year’s baby adders in late September – just before entering Brumation

For our apparently disappeared insects they have hit the “pause” button too and entered a stage known as diapause. . It refers to the interruption of an insect’s development as a response to environmental pressures. During this time– they don’t ‘age’. For insects, this can occur in embryos, larvae, pupae, or adults.

Comma butterfly – one of the few butterflies to overwinter as adults.
Light returning

The days are lengthening and with it the return of light. This shaft of light in the forest is a glimpse of the optimism of spring.

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