Category: Garden

Sparrows on the Shed

roofing felt x 60

This photograph looks rather like a scree-slope on a Lakeland fell but in fact each of these slate-like fragments is less than a millimetre across, smaller than the commas on this page. It’s a piece of roofing felt taken at 60x magnification through my microscope. The felt is bitumen-coated with a ‘green mineral’ finish, but it looks browner in my photograph. The flaky shapes and the colour make me guess that this is a green variety of Muscovite mica called fuchsite. The flakes (laminæ) of Muscovite are thin and surprisingly flexible, so they’re ideal as a coating on rolls of roofing felt.

There’s another mineral present; the rounded, glassy mineral near the bottom left-hand corner is a worn grain of sand, silica.

Fuchsite is rich in chromium but like other micas, as a form of silicate, it has a chemical composition based on aluminium, silica and oxygen (AlSi3O10). Micas are part of the group of minerals known as Phyllosilicates or sheet silicates, which take their name from phyllon, the Greek for leaf.

sparrows on the shedIt was sparrows pecking on our newly felted shed roof that prompted me to take a closer look at its composition. Why should sparrows feel the need to peck at flakes of mica?

Muscovite is 2-4 on the Mohs scale of hardness, depending whether you’re testing the softer ‘sides’ or the harder face of the flakes. This means that it’s somewhere between a finger-nail and a pocket-knife in hardness, so the sparrows might swallow it as a form of ‘gritting’. The flakes might be used in the bird’s gizzard to help grind down the seeds and grain that form its staple diet. Fuchsite is made of clayey minerals so it might also have medicinal properties that help with digestion, just as we’d take kaolin, a fine white clay that is another form of sheet sillicate.

sparrows on a wallSparrows will also peck at mortar on walls (right), which gives them access to more minerals; silica in the sand and the calcium carbonate in the cement.

When Paul and I put the new roofing felt I predicted that the sparrows would love it: “It’s like putting a new sheet of Tydsan in a budgie’s cage!”

Tydsan is the trade name of sheets of sandpaper, cut to size.

“Our budgies had to make do with newspaper in their cages!” Paul tells me.

Shed Roof

garden shed
Our garden shed in its heyday, painted as a sample when I was working on illustrations for Dr Hessayon's Garden Expert guides.

Paul the gardener tells me that one year he and his father decided to record all the produce they harvested from their vegetable garden, which is about the size of a tennis court. The total weight of apples, onions, potatoes, carrots, cabbages, soft fruits and so on was three-quarters of a ton!

This morning we’re re-roofing my garden shed.

garden path“That should last us out!” he suggests.

Well, I hope it doesn’t last us out but I think it’s got a chance of lasting out the twenty-year old shed itself, which is looking rather battered and weatherworn where we’ve cut back the Ivy that engulfed it.

Spot the shed! – in this photograph of the back garden (right), the Ivy-covered shed is on the right. People would walk down the path and not notice that we had a shed until they walked back up and saw the side with the door in.