Taxonomy terms being displayed under wrong item

Issue Summary

Hi there, I'm creating a custom content type to display information on beetle species. Here is a test page (with no formatting yet!):
http://www.carabusonline.co.uk/en/content/test-2

The problem is the parent distribution taxon term is being added to the author term. Both are taxonomies, but linked to different vocabularies. I use a select list for the distribution widget and an autocomplete widget for the author. I've deleted both fields and re-added them, but it still adds the parent distribution term to the author field (in this case Africa).

Habitat and Distribution are also autocomplete taxonomy fields so I'm not sure why it's only picking on author.

Any help greatly appreciated!!!
Matt