Alright, the title may be misleading, as I suppose this is a dark morph of a Eurasian Tree Sparrow. This was taken in the Taitung Train Station in Southeastern Taiwan, where, as with every other urban area in Taiwan, the ETS is very numerous. This one caught my eye, as I had never seen a sparrow with noticeably different plumage. I don't have much to say on the topic, as I don't know anything about it, but I thought I might post a picture in case it was of interest to anyone else.