30 Dec The Mystery of the Yellow Snow
Venturing out this morning, eyes squinting in the silver-haze sunlight, I discovered my local patch was coated in beautiful, crisp white powder. Blackbirds scurried hurridly from fallen wild apples, Long-tailed Tits eyed me from above and Pheasants caused a ruckus in the valley. I was walking towards a stream that connects to the River Leven, taking a couple of hours to explore the beautiful snow-dusted landscape.
Exploring in weather like this is a favourite of mine, the snow draws out wildlife in search of food, which leave their trails and tracks behind. Mine were the only human prints on my journey, but I shared the route with Carrion Crows, (lots of ) Pheasants and a bounding Hare – all evident from their distinctive footprints, tail-trails and gaits.
When I’m in this tracking mindset (although I’m rarely out of it!) I naturally tune deeper into my senses and notice the smaller things – as will you. Walking further along the stream, I admired the Alder trees that relied on its watery banks to survive, and vice versa. Following from branches to trunks, my eyes were led to the thick folds of snow lying beneath them. A yellow patch caught my eye amidst the bright white, and I immediately thought of that wise old phrase, “don’t eat the yellow snow” – I’ll just skip past explaining that one …
Perhaps a wandering Roe Deer had found a scenic spot by the riverside Alders to urinate? Not likely as there were no tracks to be found, and he would also have required the bladder of an elephant for the amount of yellow snow I was discovering! So an animal wasn’t an option.
Now quickly back to the Alder; it’s the single deciduous tree in Britain which can produce cones, with only the females doing so, and the males producing long pendulous catkins. These small brown cones were hanging from my riverside Alders, and I admired the dew drops of the melting snow gently lingering on them, glinting in the low winter sunlight. Strangely, many of the dew drops were bright yellow, umber and orange – hanging directly above the (don’t eat the..) yellow snow.
Male Alders are known for producing sunlight-yellow pollen on their catkins in the spring, but could that be the cause? It is after all winter, with no pollen in sight.
As it happens, Alder cones contain high levels of tannins and humins; organic compounds which are yellow-brown in colour, the former particularly being renowned for its staining properties. In fact Alder cones are added to aquariums to reduce the pH of the water, but are added in low numbers as they make the water…you guessed it… yellow!
Aquarium owners mimic the natural pH reducing and nutrient enriching qualities of fallen Alder leaves and catkins by adding them to their containers; enabling plants, shrimp and fish to thrive – just as occurs in the wild.
And there we have it! The snow which had been resting on the Alder trees throughout the night had absorbed the tannin from the catkin cones, and ever-so-slowly dripped onto the bright white snow beneath.
Mystery solved! But perhaps still avoid eating the yellow snow, just in case…