Can anyone identify these birds?

I was riding my bicycle on the bike trail along the Mississippi just west of downtown Rock Island when I saw this flock of birds beside the river.

One of them took off and I got this picture as it flew over me.


I can identify egrets, herons, geese and ducks, all of which were nearby and I can say with some confidence that these birds were not any of those. Although you can not see it in the pictures I thought I saw a little red around their heads. That makes me think they may be wild turkeys, but they don't look like any of the pictures of turkeys I can find.