Very foxes are smart. Lots of foxes live in the city but sleep during the day under buildings and move around and hunt at night. So yes, they are very smart and sneaky.
There is very little information in scientific literature about the intelligence of fennec foxes in particular. Speaking of foxes in general, Nobel Prize winner Korad Lorenz claims that foxes are not nearly as smart as wolves or dogs.
Some species are, but not all. Foxes are very smart and are scared of all types of dogs.
The myth is that foxes use their tails to clear away their own foot-prints. Smart animals :-)
Generally, predators have more highly-developed brains than prey animals, as it takes more skills to hunt than to hide. It would be fair to say that foxes are "smart" in the ways foxes need to be smart, and mice are smart in the ways mice need. Neither is likely to compose a haiku.
If given a chance, black bears will eat foxes along with other small mammals. The bulk of their diet consists of vegetation. They love honey and will eat hives, insects and all, despite getting stings on their paws.
Some are very smart, others, not so much. The red fox is known to be very clever, so it is comparably smarter then some breeds of dogs, however a border collie, is smarter than a red fox.
The collective noun for foxes is a leash of foxes. Another collective noun for foxes is a skulk of foxes.
"Urban" foxes, "City" foxes or "Urbanised" foxes.
A leash of foxes is a name for an animal grouping, in this case foxes. Think flock of birds, leash of foxes.
There are no Antarctic foxes. There are, however, Arctic foxes.
There are no "Polar foxes." There are, however, Arctic foxes and they are not endangered.
Foxes.