At this time of year in particular, you may see bright yellow Siskin in the tops of trees – I see them in Alder, picking at the seeds in gangs. They are particularly yellow and streaky, so quite different from Greenfinches, which are probably the closest other UK bird.

The picture above shows one at a feeder. It's a shame it wouldn't turn to face the camera properly – but this gives a really good view of the colourful plumage. Note that it's covered in yellow stripes whereas a Greenfinch has just the one big yellow bar along the edge of its wing. Below is a shot of a gang of them in their more natural environment feeding on Alder, though it can be hard to get a good photo as they're often high up and silhouetted against the sky.