Results include current living foxes, foxes that have been hit by cars (or died by other means), foxes that have moved out of the area, and fox kits
Here is a very watered-down and simplistic version of my data:
In a 24 acre plot, there were 3 individual red foxes
In a 60 acre plot, there were 4 individual red foxes.
In a 350 acre plot, I've found that there were at least 7 individual red foxes.
In a 430 acre plot, there were 9 individual red foxes.
In a 600 acre plot, there were 9 individual red foxes.
I get this data by comparing camera-trap images of different cameras set up in each park. A red fox that appears at one camera (under normal circumstances) cannot be the same red fox that appears at another camera 1 mile away, 30 seconds later. BAM! That's two individual foxes. Some red foxes look completely different from eachother, others are a little more difficult to recognize. Figure in more parks and a heck of a lot more cameras, and results like this pour in to my computer on a daily basis.