The gaggle of Mallard that wasn't

I was over at Loch of Kinnordy yesterday, photos to follow but, I'd logged 100+ Mallard ..... way across the other side of the loch but, when I looked at the photos just now, they're not! They're Teal (I think) but in amongst them is something different, bigger? Anyone able to ID it for me please? 

Left of centre in the wide shot and centre in the cropped in version, there are also two bigger birds top right in the second shot.

Many thanks in advance