Category: Birds

The Hawk and the Squirrel

Harris HawkWatching a Grey Squirrel carrying bedding to its drey the other day, I was thinking what an easy life these suburban squirrels must have, with no natural enemies apart from the occasional Fox, which can’t follow them up into the tree-tops. But the squirrels of Spring Mill Park must be well aware of one powerful predator that has been hawking around the area for the last 14 years; this North American Harris Hawk, Parabuteo unicinctus, one of three which belong to a local falconer.

grey squirrelHe exercises them regularly but confides to me that it’s now getting a bit too much for him. When the bird goes down on prey it’s not like a retriever dog, it won’t bring the prey back to him, so it might end up half a mile away – as the hawk flies – up the slope in one of the pastures between Spring Mill Park and the motorway.

This hawk can easily tackle prey such as Rabbits and Magpies but if you’re hawking for Grey Squirrels – which, for all their cuteness, are often seen as a pest species, here in Britain where they’ve been introduced – the hawk needs to be equipped with special leg-guards as the squirrel, when caught, can swivel around and use its impressive incisors to bite into the back of the hawk’s legs, potentially inflicting permanent damage.

Flying weight is critical for hawking; fly a bird that’s even a few grams over its ideal weight and it will happily soar about all day without bothering to go for prey. This female Harris Hawk, I’m informed, needs to weigh in at precisely 2 pounds, 1 ounce and 3 grams, when it is taken out to hunt.

goshawkThe falconer was once surprised, when he was calling back one of his hawks, by the sudden appearance of a Goshawk which flew down and perched on the fence nearby. It had jesses so he managed to get near it and take it back to his avairy. The ring, which all captive falcons wear, revealed that it had been lost by a falconer who lives at Addingham, 23 miles to the north-west of Spring Mill, so he was able to reunite the bird with its owner.

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.

Fieldfares in the Crab Apple

redwingredwingsWhen the snow returned yesterday morning almost an inch fell, although it wasn’t as cold as it was after last year’s snowfalls. When I’ve cleared the driveway it’s been powdery but yesterday afternoon it was just starting to turn slushy, so it was heavier and slushily sticky to clear from the paving slabs. Powdery snow leaves the driveway cleaner; slush leaves it damp and filthy.

golden hornetAs the snow fell, Blackbirds, Fieldfares and Redwings came to the Golden Hornet crab apple, the one that we pruned on Monday. The snow-covered little apples, golden until mid-autumn (left) but now frosted and brown, proved a big attraction. We counted eight Redwings and five Fieldfare around midday, although I guess that at times there were more.

redwingfieldfareMy pen and ink drawings from my 1979 Sketchbook of the Natural History of the Country Round Wakefield don’t do justice to these attractive winter thrushes. The Fieldfare’s light grey, chestnut and whitish plumage is striking against a snowy landscape, as is the chestnut red beneath the wings of the Redwing. I often have difficulty picking out the red of the Redwing when I see it in silhouette in bushes or in flight but it was very obvious today, at close quarters seen through the 10 x 50 binoculars that I keep by the studio window.

The shapes of the birds were different today; Blackbird, Redwing and Fieldfare all had a more rounded silhouette as they had their feathers fluffed out against the cold.