It is very rare for wolves to die when they hunt for prey. In addition, wolves are an apex predator, meaning that they aren't prey to any other animals.
Wolves are very rarely killed due to/in the process of, predation.
There is little to no wolf deaths due to sexual competition; this is because, for the most part, wolf packs only have 1 pair of wolves that reproduce.
There are no major diseases in wolves, unlike deer with Chronic Wasting Disease. A list of infections/parasites that wolves have been encountered having includes:
Rabies, Canine Distemper, Infectious Canine Hepatitis, Canine Parvovirus, Oral Papillomatosis, Brucellosis, Leptospirosis, Lyme Disease, Tularemia, Bovine Tuberculosis, Blastomycosis, Dog Heartworm, Dog Hookworm, Liver FLuke, Hydatid Tapeworm, Lice, Mites (mange)
As shown, humans contribute the largest part to the deaths of wolves.
Humans have interacted with wolves for around 15,000 to 40,000 years. Since some are suspected to have been domesticated, leading to C. l. familiaris (the domestic dog).
When Europeans first came to North America they slowly began to eradicate the wolf populations, to keep their towns/cities/villages safe from wolf attacks, and importantly, to prevent depredation of their cattle. This led to wolves being almost extinct. They were fully wiped out of Yellowstone and had to be re-introduced.
Wolves were listed as endangered in 1974 by the U.S. Fish and Wildlife Service. They were delisted in 2012. Though in 2014, a US Federal Court ordered a stop to the hunting of wolves in Michigan, Minnesota, and Wisconsin.
Least Concern.
Population is unknown, though suspected to be between 200,000 and 250,000. There is a trend of wolf populations going up.