H5 in swans in Croatia - what swan?

From ProMED:

Avian influenza in Croatia
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Information received on 21 Oct 2005 from Dr. Mate Brstilo, Director of the
Veterinary Administration, Ministry of Agriculture and Forestry, Zagreb:

Report date: 21 Oct 2005.

An outbreak of avian influenza was reported in wild migratory swans in
Zdenci municipality, Viroviticko-Podravska county. Out of approximately
1500 wild migratory swans, 15 birds died.

The OIE should start requiring more information the species of migratory birds that are found with high path avian influenza. Knowing which species were tested (and report negatives AND positives) can go a long way to help us understand the epizootiology of this disease. Where do these swans migrate? How do we know they were really migratory (there are many species of birds that are resident, and even some populations within normally migratory species do not migrate, e.g., Canada geese).