Xenophobic Duck... Fight To The Death...

Info From Licensor: "While setting up our cameras for a Tri-Athlon in Cape Town we witnessed these two Geese/Ducks having it out, not understanding what or why they were doing this I posted it to YouTube in the hopes that someone could explain such aggression even to the point of death.. never seen this in birds to this extent..."
Location: Cape Town , South Africa
Occurrence Date: March 6, 2015