title: Spatiotemporal requirements of the Hainan gibbon: Does home range constrain recovery of the world's rarest ape?
abstract: Conservation management requires an evidence-based approach, as uninformed decisions can signify the difference between species recovery and loss. The Hainan gibbon, the world's rarest ape, reportedly exploits the largest home range of any gibbon species, with these apparently large spatial requirements potentially limiting population recovery. However, previous home range assessments rarely reported survey methods, effort, or analytical approaches, hindering critical evaluation of estimate reliability. For extremely rare species where data collection is challenging, it also is unclear what impact such limitations have on estimating home range requirements. We re-evaluated Hainan gibbon spatial ecology using 75 hr of observations from 35 contact days over 93 field-days across dry (November 2010-February 2011) and wet (June 2011-September 2011) seasons. We calculated home range area for three social groups (N = 21 individuals) across the sampling period, seasonal estimates for one group (based on 24 days of observation; 12 days per season), and between-group home range overlap using multiple approaches (Minimum Convex Polygon, Kernel Density Estimation, Local Convex Hull, Brownian Bridge Movement Model), and assessed estimate reliability and representativeness using three approaches (Incremental Area Analysis, spatial concordance, and exclusion of expected holes). We estimated a yearly home range of 1-2 km2, with 1.49 km2closest to the median of all estimates. Although Hainan gibbon spatial requirements are relatively large for gibbons, our new estimates are smaller than previous estimates used to explain the species' limited recovery, suggesting that habitat availability may be less important in limiting population growth. We argue that other ecological, genetic, and/or anthropogenic factors are more likely to constrain Hainan gibbon recovery, and conservation attention should focus on elucidating and managing these factors.
  Re-evaluation reveals Hainan gibbon home range as c. 1-2 km2. Hainan gibbon home range is, therefore, similar to other Nomascus gibbons. Limited data for extremely rare species does not necessarily prevent derivation of robust home range estimates.
authors.affiliation: Institute of Zoology, Zoological Society of London, London, UK.|Department of Genetics, Evolution & Environment, University College London, London, UK.
authors.forename: Jessica V
authors.initials: JV
authors.lastname: Bryant
authors.affiliation: Bawangling National Nature Reserve Management Office, Changjiang Lizu Autonomous County, Hainan, China.
authors.forename: Xingyuan
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Bawangling National Nature Reserve Management Office, Changjiang Lizu Autonomous County, Hainan, China.
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Hong
authors.affiliation: Department of Genetics, Evolution & Environment, University College London, London, UK.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Chatterjee
authors.affiliation: Institute of Zoology, Zoological Society of London, London, UK.
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Turvey
mesh_terms: D000818:Animals; D017753:Ecosystem; D056727:Endangered Species; D006702:Homing Behavior; D006922:Hylobates; D015203:Reproducibility of Results; D012621:Seasons
keywords: KDE; LoCoH; Nomascus hainanus; home range estimation; spatial ecology