Thanks very much to Mark Pollitt who did a few 'rough and ready' checks and was able to suggest that it looks like Bird-Red and Bird-Amber are ok for BoCC 4.  The descriptions don't seem the clearest to reflect that, but that could just be me.

Running report Sy05 - Taxon designations available for sets (Reports > Run > System Supplied > Information) gives the right number of species for amber (96) and red (67), which is hopeful!

There's another report that would have been useful, but I couldn't get it to work for either of these designations.

The report I wanted to use was Des1_Taxa in Designation Type (under Reports > Run > System supplied > Information), which says it takes the name of the Taxon Designation Type or the key.  I tried the long and short names (Bird Population Status - red, Bird-Red, Bird Population Status - amber and Bird-Amber) as well as the keys (NHMSYS0020443052 and NHMSYS0020443051) but was presented with an empty report each time.

If anyone can see that I've done something daft that's stopping it working, please let me know :)

Thanks,
Linds