Hey big...
First of all, winter is the best time to visit, less people, no leaf cover.
As others have posted, follow the paths. However, these are the three best spots.
The marsh area just off the parking lot;
Google coordinates; 43.670487,-79.513931
The path near the stream;
Google coordinates; 43.668904,-79.513094
The feeder area;
Google coordinates; 43.666253,-79.514049
I had a guy tell me one day while I was at Cranberry Marsh that James Gardens/Lambton Woods was the "Woodpecker capitol of the GTA"
Hey Bob, that was me!