Greater or lesser Yellowlegs (1 Viewer)

[Jack87]

Seen today, 4/29/21 at Lee Metcalf NWR near Stevensville, Montana. Looks like lesser to me but lesser is relatively rare in the area compared to the more common greater.

Bird in background is a gadwall for reference.

 

[Indobirder]

Based on size, I would call this a Greater. The bill isn't clear, but it doesn't look wrong for Greater

Why do you think it's a lesser?