You might enjoy this research paper - click the "download PDF" link.

The authors look at the discovery of ravens and crows in a number of pre-Roman British burial sites. They describe the finds and review the debate over their meaning. It's a fascinating paper, which reminds us to think carefully about the biases and expectations that influence our conclusions. It doesn't provide easy answers, and you can feel the authors' happy fascination with an ancient mystery as they write. It's a lot of fun.