New Arrivals!

 There's all sorts of bird movements going on at the minute-but here's two examples of completely different movements that we have encountered in the last few days......

Over the last few weeks, hirundines ( Swallows, House and Sand Martins ) have been arriving in their thousands. Many observers are reporting for the second year running, much fewer birds around than even a couple of years ago. However, on cold/damp mornings in our summer/late spring; these birds find it more difficult to find their staple food--flying insects. This is when sewage works can come into their own. The filter beds are breeding grounds for many insects and as they hatch and fly off, they provide good feeding or hirundines--which come down low enough to be caught for ringing. There haven't been many suitable days recently, but Paul managed a short session before the sun came out and the birds disappeared. He caught a few Swallows and House Martins--and here are a couple of pictures to illustrate one or two points........

Here is the tail of a Swallow showing the long outer tail feathers or 'streamers' as they are called. Research on this species suggests that the longer the streamers are as sign that birds are male--and furthermore, the longer the streamers, the more successful a male is in attracting a mate.........we measure the length of the streamer back to the other tail feathers to determine the sex.

Here is a House Martin ( not a very flattering pic but taken to show a couple of features. Firts, we often get asked about how to tell the difference between hirundines--in the UK, House Martins are the only species with a white rump as shown here. This picture also shows the complete uniform blue back typical of a bird having just completed a pre-breeding moult in it's African wintering grounds. As we'll see later in the year, juvenile birds have mixture of blue and grey brown feathers here.

So, here we have some new arrivals from thousands of miles away which have come here to breed during our summer. Now lets jump across to Pat's garden in mid Wales, and some new arrivals have been ringed--but from a very different source......

Here is a newly fledged ( recently left the nest) Siskin. Presumably just arrived from an egg in a nest not too far away from Pat's garden. You can see how generally speckled it is, and a closer look at the stripes on the wings there is quite a bit of buff colour--here's a picture of the wing in close up....

1 are called median coverts, 2 are called tertials and 3 are called greater coverts--and their edges are all creamy/buff with just a hint of green.

Over the next few weeks many of these feathers will be moulted and replaced with completely different coloured feathers as shown by this older bird....

As you can see, many of the buffy feathers have been replaced--but not all--the outer greater coverts as indicated are shorter with white tips, then the older more adult like greater coverts to their left. 

In stark contrast is the wing of an adult Siskin---

( Please ignore the number!!) Here you can see all the feathers mentioned earlier are brightly coloured green and yellow, with no sign of any remnant juvenile feathers. Here's an adult male Siskin to compare with the fledgling above..

Also at this time of year we often get birds showing signs that they are/have been actually breeding. Female birds develop what is called a 'brood patch' which is where they lose their belly feathers in order to have bare skin with which to keep their eggs warm. The skin becomes wrinkled to increase its surface area, and engorged with blood vessels for added heat. Here is a brood patch shown by one of the Siskins recently ringed in Pat's garden.

When you see birds settling down onto the nest you often see them wriggle about a bit--that's their way of ensuring their feathers have parted to ensure the brood patch is in touch with the eggs..... aren't birds brilliant!!