It seems that several of the Shelducks have been assigned incorrect RECOMMENDED_TAXON_LIST_ITEM_KEYs. Here are the TLIKs for each of the dodgy ones:

NHMSYS0001771325
NBNSYS0000155183
NBNSYS0000126581
NBNSYS0100003117
NHMSYS0019998249

Run the following to see the full record for each:

select 
  *
from
  index_taxon_name
where
  common_name like '%shelduck' and
  recommended_taxon_list_item_key = 'NHMSYS0019998249'

The recommended taxon each of these points to is on the "The population status of birds in the UK. Birds of Conservation Concern: 2002-2007" list, which is a designation list.

The correct RECOMMENDED_TAXON_LIST_ITEM_KEY should, I believe, be this:

NHMSYS0000529965

Charles