ORIGINAL: jhoffman
One more thing. I have noticed is that the coyote put a real dent in the gray fox population too. I used to have 3 to 5 grays come in at any given time when I was out calling now when and if they come in its usually only one maybe two and when they come the come in a hurry to beet the competition to the dinner table. Gray don't stand a chance against a coyote they only have being able to high tail it up a tree to thier advantage.
Although it is certainly possible, it is not likely that this is the only cause. Grey fox are widely known to be able to survive in yote territory. Red fox are the ones normally pushed out.
This has been well known for years and years. Ask any longtime trapper, and they will agree. Dobbins I believe even covered the topic.
Not only can they climb, but litters are often had in the trees when coyotes move into a territory. Plus the grey fox can easily out manuver a single or pair of yotes. The advantage shifts to the yotes when pack hunting, but rarely is a grey fox pushed out of an area.
Plus you have to consider density numbers. Coyotes roam more ground, in less numbers. Gray fox roam less ground in more defined territorial numbers.
Go to trapperman.com and post there, and some of those wise men can tell you more, they really know their stuff there.