Lone ant, shiny, with small spikes
I have observed for the past years that terns and herons shows up in the river towards the end of the year. Today (4th. of January 2015) I had the opportunity to photograph the terns feeding while going against the slow flow of the water. The group of terns in the section of the river I was, was around 15.
Initially I identified as a black-nape tern, but further research convinced me it was the Aleutian tern.
References:
http://www.avibirds.com/html/Aleutian_Tern.html
http://www.birdlife.org/datazone/speciesfactsheet.php?id=3285
In some standing water. 400x magnification. Slowly waves around and then retracts quickly along that line coming out the back of it.