Rhinos in the Parks: An Island-Wide Survey of the Last Wild Population of the Sumatran Rhinoceros

Abstract

In the 200 years since the Sumatran rhinoceros was first scientifically described (Fisher 1814), the range of the species has contracted from a broad region in Southeast Asia to three areas on the island of Sumatra and one in Kalimantan, Indonesia. Assessing population and spatial distribution of this very rare species is challenging because of their elusiveness and very low population number. Using an occupancy model with spatial dependency, we assessed the fraction of the total landscape occupied by Sumatran rhinos over a 30,345-km2 survey area and the effects of covariates in the areas where they are known to occur. In the Leuser Landscape (surveyed in 2007), the model averaging result of conditional occupancy estimate was or 2,371.47 km2, and the model averaging result of replicated level detection probability ; in Way Kambas National Park—2008: or 634.18 km2, and ; and in Bukit Barisan Selatan National Park—2010: or 819.67 km2, and . In the Leuser Landscape, rhino occurrence was positively associated with primary dry land forest and rivers, and negatively associated with the presence of a road. In Way Kambas, occurrence was negatively associated with the presence of a road. In Bukit Barisan Selatan, occurrence was negatively associated with presence of primary dryland forest and rivers. Using the probabilities of site occupancy, we developed spatially explicit maps that can be used to outline intensive protection zones for in-situ conservation efforts, and provide a detailed assessment of conserving Sumatran rhinos in the wild. We summarize our core recommendation in four points: consolidate small population, strong protection, determine the percentage of breeding females, and recognize the cost of doing nothing. To reduce the probability of poaching, here we present only the randomized location of site level occupancy in our result while retaining the overall estimation of occupancy for a given area.

Habitat utilization of the Sumatran rhinos (Dicerorhinus sumatrensis harrissoni) in Kutai Barat forest, East Kalimantan, Indonesia

“…In total, 294 coordinates were representing the rhino's signs (Ginanjar 2016, pers.com). The habitat components were divided into eight variables including distance from roads (X1), rivers (X2), wallows (X3), salt licks (X4), slope (X5), elevation (X6), Normalized Difference Vegetation Index/NDVI (X7), and soils (X8) (Santosa et al 2013;Putra et al 2014;Pusparini et al 2015;Rusman 2016). To simplify the analysis process, each variable was classified (Table 1).…”

“…Numerous records reveal that the Sumatran rhinos mainly occur in coastal swamp forest, lowland, and mountain forest (van Strien 1985;Pusparini et al 2015). According to Plair et al (2011), the Sumatran rhino is a solitary species.…”

“…However, this species could occasionally be found in a small group consisting of two or more individuals (van Strien 1985;Plair et al 2011). The Sumatran rhinos appear to exhibit habitat preferences influenced by food abundance, topography, the source of minerals and water, and human presence (van Strien 1974;van Strien 1985;Pusparini et al 2015;Kretzschmar et al 2016). Therefore, within the utilized habitat, different environmental factors may interact to affect their presence.…”

“…Accordingly, there is a need to understand habitat preferences and utilization of the Sumatran rhinos in Kalimantan, particularly in the Kutai Barat forest. Since the Sumatran rhinos show different responses to environmental conditions (Pusparini et al 2015), research related to this field is urgent to enrich ecological information.…”

“…Preferred habitat with an optimum condition is definitely capable of maintaining a sustainable population. Knowledge of habitat preferences can be applied to assist habitat and population management of the Sumatran rhinos in the wild such as Intensive Protection Zone (IPZ), which is an exclusive area for insitu conservation with strict protection (Pusparini et al 2015;Rusman 2016). In addition, information on habitat preferences is also beneficial to support the establishment of restricted breeding areas and corridors.…”