Black wildebeest
Black wildebeest act as hosts to a number of external and internal parasites. A study of the animal in Karroid Mountainveld (Eastern Cape Province, South Africa) revealed the presence of all the larval stages of the nasal bot flies "Oestrus variolosus" and "Gedoelstia hässleri". The first instar larvae of "G. hässleri" were found in large numbers on the dura mater of wildebeest calves, specially between June and August, and these later migrated to the nasal passages. Repeated outbreaks of mange (scab) have led to large-scale extinctions. The first study of the protozoa in blue and black wildebeest showed the presence of 23 protozoan species in the rumen, with "Diplodinium bubalidis" and "Ostracodinium damaliscus" common in all the animals.
Yellowstone National Park
By the 1990s, the Federal government had reversed its views on wolves. In a controversial decision by the U.S. Fish and Wildlife Service (which oversees threatened and endangered species), northwestern wolves imported from Canada were reintroduced into the park. Reintroduction efforts have been successful with populations remaining relatively stable. A survey conducted in 2005 reported that there were 13 wolf packs, totaling 118 individuals in Yellowstone and 326 in the entire ecosystem. These park figures were lower than those reported in 2004 but may be attributable to wolf migration to other nearby areas as suggested by the substantial increase in the Montana population during that interval. Almost all the wolves documented were descended from the 66 wolves reintroduced in 1995–96. The recovery of populations throughout the states of Wyoming, Montana and Idaho has been so successful that on February 27, 2008, the U.S. Fish and Wildlife Service removed the Northern Rocky Mountain wolf population from the endangered species list.
Black bears are common in the park and were a park symbol due to visitor interaction with the bears starting in 1910. Feeding and close contact with bears has not been permitted since the 1960s to reduce their desire for human foods. Yellowstone is one of the few places in the United States where black bears can be seen coexisting with grizzly bears. Black bear observations occur most often in the park's northern ranges and in the Bechler area which is in the park's southwestern corner.