Nesting has begun at Renton's Black River Riparian Forest. I visited this past weekend and we saw about 30 herons. Some were even standing in nests and one was pointing his/her beak skyward to let the others know that they were looking for a mate. 

If you'd like to see the nesting herons at Black River before the cottonwoods leaf out, this will be the time to do it. Once the trees are leafed out, the nests will be very difficult to see.