I live in the mountains, so I have lots of opportunities. We go for hikes or rides several times a week. We see tons of things - because we are out there so often. We have deer, bears, raccoons, birds, elk, lions and coyotes in the yard... I actually have teeth marks on my deck from a Grizzly bear that stopped by a few years ago.
In the case of these foxes, we found this den (these are babies) a week ago. It is in a perfect place for evening "golden" sunlight as it sets. We use no fill flash here.
With these foxes, my wife shoots a 40d with a 100-400 and I shoot a 1D Mark III with the 500mm. The foxes are approx. 30 feet from us. We "as a rule with wildlife shoot ISO 400 and AV mode (most of the time).
We get there early in the evening and get set up. We spend about 3 hours a night when we are trying to get pictures. Sometimes we wait an hour for them to come out of the den, sometimes they never show. Lots of waiting..
When they do arrive, we constantly follow them through the lens - waiting for the eyes to come our way. When they do we "click" - We probably take about 100 images each per night -