There are few things in the natural world more complex and highly evolved than feathers. We take them so much for granted as we see them blowing about in the wind or lining a bird's nest, but they really do demand a closer look. Having found a primary (flight feather) from a House Sparrow (Passer domesticus) on our front garden this morning, I thought it would be good to have a closer look, under the microscope. Here, magnified 10 times, you can see the individual filaments separating along the trailing edge of the feather.
The ends of these feathers look 'tatty' under the microscope, as they disintegrate into a fine powder which is combed into the feathers to help waterproof them. It is this powder (along with various feather parasites and their droppings) which can be such a problem to some people producing allergic reactions and breathing difficulties.