Swans are, as most people know,  large white birds related to geese. However, as this still from a video shows, they can appear black. It simply depends on the background and source of illumination. When seen on water and from a low angle it can very difficult to accurately estimate the size or distance of objects. The human eye and brain are very good at computing sizes, distances and speeds at close ranges, but easily make mistakes at greater ranges.

The same fearsome beastie from the top of the page
Copyright 2000 Dick Raynor
 

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