Birds of a feather

I was out walking recently along a hedgerow in a stubble field at Baptist Grange. I picked up this beautiful feather and took it home to identify it. From my reference book I was able to identify it as a primary feather from a Long-eared Owl. It has three very important characteristics. Firstly, it has cryptic colouring with patches of dark brown and fawn. These colours allow the owl to roost in a tree during the daytime and to be perfectly camouflaged. Secondly, it is quite broad for a primary feather. The wing of an owl is broad to give maximum lift because they hunt by quartering the ground in slow flight. Thirdly, the surface of the feather is very soft and feels like a very soft tissue. This allows the owl to have almost silent flight, so that its prey doesn’t hear it coming.

Birds are the only creatures on the planet to have feathers. Birds evolved from reptiles many millions of years ago. They still have reptilian features like horny scales and claws on their legs and they lay eggs. It appears that feathers evolved from modified scales but we can’t be certain. The first bird to appear in the fossil record 140 million years ago, Archaeopteryx, had a full set of feathers and it was flying about, over the heads of dinosaurs.

Long-eared Owl feather

Feathers have many functions. First and foremost, they facilitate powered flight. A bird can spread its wings and take off because these structures are strong but very light. The wing feathers provide the lift while the tail feathers act as a rudder to control direction. Body feathers are responsible for insulation. The down from the body of the eider duck is famous for its insulating properties.

The feathers can also be used in communication. In this part of the world, the plumage of female birds is usually subdued because they don’t want to draw attention to themselves as they sit on the nest. The males however, are free to display what fine specimens they are. The huge energy that goes into growing a peacock’s tail, for example, shows how important the display is to that species. A displaying Snipe can use its outer tail feathers to produce a ‘whinneying’ sound as it flies over its breeding grounds.

But these beautiful plumes suffer wear and tear during the breeding season. The old feathers are dropped and a new set of feathers are grown during the moult every year. These new feathers are carefully maintained by preening. Each feather has a central vane and this supports the barbs which bind together using barbules. These barbs are re-arranged during preening. Birds spread oil on their feathers to maintain them and to make them waterproof. The oil comes from a gland just above the tail.

2012 – A terrible year for breeding birds.

It’s been a terrible year for breeding birds in Tipperary and certain groups of birds have been particularly badly hit. I have already written about the plight of our Kingfishers and it likely that most pairs of Kingfishers produced no young at all this year. The other large group which has suffered are the insect-eaters. The summer has been so wet and miserable that very few insects emerged. Species which catch insects in the air such as Swallows, House Martins, Sand Martins and Swifts will have had a hard time finding enough food for themselves, never mind feeding hungry chicks.

Swallow's nest with 5 eggs in 2008

Our Swallows arrived at the usual time. I saw my first Swallows near Moyglass on 27^th March. They flew around our house all through April and May but they were very slow to build a nest. This was clearly a sign that the females could not get enough food to get into breeding condition. They finally got going in June and laid their first egg on 24^th June. This was three to four weeks late. In 2010 their first egg was laid on 12^th May and the average over the past 6 years has been the 23^rd May.

This year they laid 4 eggs and only 3 chicks successfully fledged. The average number of chicks they usually have is 4.4 and, very importantly, they usually have two broods. The second clutch is usually started in mid-July. I usually have two pairs nesting at the house, but this year only one pair nested. In an average year the Swallows at our house in Lisronagh would produce 16 or 17 chicks whereas this year they only produced 3. So their productivity this year only one sixth of what it should be.

Of course, Swallows have been migrating to this misty island for thousands of years and are able to deal with one bad summer. They usually bounce back the next year and produce more chicks and in the long run, everything balances out. But what if the next summer is unusually wet and the following one is unusually wet? What if the pattern of our weather has changed due to climate change? We seem to get good weather in April and September and monsoon type weather during May to August. The Swallows have evolved to migrate and breed here during what should be the ‘summer’ months. They can’t just change their flight plans.