Nina Eide, one of the arctic fox specialists of NINA
The Norwegian tv (NRK) filmed scientists from Th Norwegian Institute for Nature Research (NINA) who work on a breeding program for arctic foxes which is an endangered species in Norway and Sweden. The result was broadcasted in October 2009 within the program Ut i naturen. There you can see the foxes at the breeding station in Sætrefjell station, where they kept 5 fox pairs in huge fences and monitor the inner site of their dens by a screen, even on internet.
When the pups grew adult, they were radio-collared, tagged and released up in the mountains.
The film can be seen here
note it is in Norwegian but the foxes "speak" a universal language