The thornbirds are related to ovenbirds such as the Rufous Hornero. There are four geographically separated races of this species. See the distribution map at Birdlife International. Photos 1 and 2 show the nominate sub-species which has a more rufous forehead.

The most noticeable feature of these rather drab birds are the enormous stick nests which they build. These can be up to 2 metres long. The scale can be judged in the photo from the thornbird sitting on the top of the nest.

You are likely to see several nests in the same tree but this does not signify that it nests in colonies. In fact, the same pair will build a new nest each year and usually in the same or a nearby tree. As a general rule, the higher the nest the more recent it will be.