Yosemite has more than 300 species of vertebrate animals, and 85 of these are native mammals. Black bears are abundant in the park, and are often involved in conflicts with humans that result in property damage and, occasionally, injuries to humans. Visitor education and bear management efforts have reduced the bear-human incidents and property damage by 90% in the past few years. Ungulates include large numbers of mule deer. Bighorn sheep formerly populated the Sierra crest, but have been reduced to several remnant populations. There are 17 species of bats, 9 of which are either Federal or California Species of Special Concern. Over 150 species of birds regularly occur in the parks. Great gray owls are of special interest in Yosemite because here they reach the furthest southern extent of their global range, and they are isolated by hundreds of miles from the next closest population in far northern California.