There are many of these spiders moving about in last years Spartina patens (cord grass); with practically every step a spider or two would come out from under the top-most blades of grass, run ahead, and disappear down into the deep layers of cord grass. Most were almost black, others a medium brown.

Rouge National Urban Park.
Zoo Road, Beare Wetland loop and Orchard trail.
Toronto Bird Celebration.
Another fantastic Guided Bird Walk. 33 birds heard and most seen. Here are the ones I was able to capture.

Came from European Swallow-Wort and landed on Common Serviceberry.