When it rains the river near the greenway rises a lot. For some reason, you'll also seen an increased number of geese around the grenway in various puddles. One stretched is just littered with poo. They also hiss at you... more so if you sneak up on them, which I did, once.
I stopped on time to see how close I had to get before they start hissing. Once you start moving at them, the bigger ones seem to turn at you and start hissing. However, if you get too close they'll run off.
I was actually taking pictures (which I don't have anymore) of my commuter to sell it. A bunch of geese came from the river and started walking over. They got pretty close to my bike (I wish I still had those picture to show), but not me.