Louisiana or Northern Waterthrush?

[rayh]

Taken in April 29 in northern Illinois.

[Hasan]

Ehh, kinda ambiguous. Any other shots?

[rayh]

That is the only one.

[Caley Thomas 2.0]

Photos aside, did you ever get a nice look at the throat?  If so, what can you tell us about it streaking-wise?  Also, would you describe the tail-bobbing as more fluid or more lurching?

[IKLland]

I wouldn’t call it from the photo, but if you did get views of the throat I would. That being said, my vote is for northern, but I wouldn’t say for sure from the photo. 

[rayh]

I didn't get a good look.  I saw it from the side, then it flew off.  I'm going to call it Northern since others have recorded Northern and not Louisiana during that period.

[Kerri]

Powdermill Nature Reserve (on facebook) recently had side by side comparisons of birds in the hand of Northern Waterthrush and Louisiana Waterthrush. Photos attached. 

[chipperatl]

Bill seems small for a Louisiana.  

[Caley Thomas 2.0]

If I had a gun to my head I'd call it a Northern, but since I don't, waterthrush sp. for me.  Tough bird to ID as the nice post by @Kerri suggests, but particularly with this single photo here.