Stealing Feathers

Another set of photos I took during the visit to Tum Phaplong last weekend. A flock of about 20 House Swifts (Apus affinis) was flying tightly in group when I arrived at the place. I've never seen the birds swifting tightly together like this before and I thought that was quite strange. The flock later dissolved when sunlight began to break through behind the tall mountains. There were several huge Brown-backed Needletails (Hirundapus giganteus) joining the group as well. I know that these House Swifts build their nests in a colony under the temple's roof so I walked in and find one to photograph. Too bad all the birds were inside their nests and flew out as soon as I walked closer to them. Anyway I still found one nest with an adult inside showing its head out of the small hole, so I could grabbed some photos before the bird flew out. Looking at the nests, I've always get fascinated by some details in the combination of the nesting materials. You can see that they use feathers, sticks, leaves and mud to build their nests, but everytime I look carefully into each nest, I often find some strange things like feathers that clearly don't belong to them. I've seen especially lots of green and yellow feathers in the combination, and I am very much puzzled by how these black and white birds got all those colourful feathers. Anyone has the answer to my question?