title: Water Use Patterns of Sympatric Przewalski's Horse and Khulan: Interspecific Comparison Reveals Niche Differences.
abstract: Acquiring water is essential for all animals, but doing so is most challenging for desert-living animals. Recently Przewalski's horse has been reintroduced to the desert area in China where the last wild surviving member of the species was seen before it vanished from China in the 1960s. Its reintroduction placed it within the range of a close evolutionary relative, the con-generic Khulan. Determining whether or not these two species experience competition and whether or not such competition was responsible for the extinction of Przewalski's horses in the wild over 50 years ago, requires identifying the fundamental and realized niches of both species. We remotely monitored the presence of both species at a variety of water points during the dry season in Kalamaili Nature Reserve, Xinjiang, China. Przewalski's horses drank twice per day mostly during daylight hours at low salinity water sources while Khulans drank mostly at night usually at high salinity water points or those far from human residences. Spatial and temporal differences in water use enables coexistence, but suggest that Przewalski's horses also restrict the actions of Khulan. Such differences in both the fundamental and realized niches were associated with differences in physiological tolerances for saline water and human activity as well as differences in aggression and dominance.
authors.affiliation: College of Nature Conservation, Beijing Forestry University, Beijing, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America; Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia, United States of America.
authors.forename: Qing S
authors.initials: QS
authors.lastname: Cao
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America.
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Rubenstein
authors.affiliation: College of Nature Conservation, Beijing Forestry University, Beijing, China.
authors.forename: Sen
authors.initials: S
authors.lastname: Zang
authors.affiliation: Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Songer
authors.affiliation: Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia, United States of America.
authors.forename: Peter
authors.initials: P
authors.lastname: Leimgruber
authors.affiliation: College of Nature Conservation, Beijing Forestry University, Beijing, China; Altai Forestry Bureau, Altai, Xinjiang, China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Chu
authors.affiliation: Wild Horse Breeding Center, Xinjiang Forestry Department, Urumqi, Xinjiang, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.affiliation: College of Nature Conservation, Beijing Forestry University, Beijing, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: College of Nature Conservation, Beijing Forestry University, Beijing, China.
authors.forename: Defu
authors.initials: D
authors.lastname: Hu
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002681:China; D002940:Circadian Rhythm; D017753:Ecosystem; D005843:Geography; D006736:Horses; D013045:Species Specificity; D061350:Sympatry; D014867:Water
chemical_list: D014867:Water