There are several problems with the Annual Reviews site that contribute to the problem. Over the past year AR has changed the presentation of their material several times and Zotero cannot keep up with the changes. Another problem is that AR doesn't provide complete, consistent and accurate metadata. It is possible to use the AR export to RIS function but depending upon the annual review title, the volume and page numbers may be missing or inaccurate(!). When a doi string is provided, it is prefaced with "doi:".

Please write to Annual Reviews and request that they attend to the metadata problems. The AR import problems affect all bibliographic database software, not just Zotero. The editors of the various AR titles expect that every article will be cited frequently. Yet, they make it difficult for authors to get accurate and complete metadata needed to assure accurate citations.

I second the request to improve the AR translator, though I will also write to them asking to be more consistent in exposing the metadata.

Right now the metadata is pretty good but PDFs are not downloaded automatically for me (example url: http://www.annualreviews.org/doi/abs/10.1146/annurev-anthro-081309-145722). Since I can simply drag the PDF on the Z item that's not too bad; but that also means that it shouldn't be too difficult to make the translator do it for me.

Ah, I see (and sorry I forgot again that you can hover over the translator icon to see what type is being used).