John Pastore writes:

Saw these Mallards Feb. 23, in Ramsey. 

I was struck by their sapphire blue (rather than emerald green) heads, but I know that digital cameras sometimes 'see things in a unique way', depending how the light is hitting the subject.  Especially something iridescent. 

I did some Googling, and found a lot of people swear to have seen dark-blue-to-purple-headed mallards.

What say our local birding community? 

Trick of the light, or a variant?