Summary

Northeast Bornean orangutans (Pongo pygmaeus morio) are present in the Imbak-Kalabakan landscape.
It has been estimated that 1,570 (CI: 1,037-2,374) individuals occur in the site.
The orangutan population trend is unknown.
The site has a total size of 4,805 km².
Key threats to orangutans are habitat fragmentation and human-orangutan conflict.
Conservation activities are not documented.

Site characteristics

The Imabalak-Kalabakan region is located in Malaysian Borneo, in the northeastern state of Sabah. The region comprises 2,175 sq.km of protected and 2,630 of unprotected areas (SWD 2020). The vegetation is characterised by a mixture of heath, lowland and upland mixed dipterocarp forests (Simon, Davis & Ancrenaz 2019). Fragmented forests, such as the Brantian-Tantulit virgin jungle, the Ulu Kalumpang Forest Reserve, and oil palm and industrial tree plantations are found in the Kalabakan landscape, where land use continues to change (Phaik Imm et al. 2021).

Table 1. Basic site information for Imbak-Kalabakan

Area	4,805 km²
Coordinates	5.013665 N, 117.177508 E
Designation	Unclassified
Habitat types	Subtropical/tropical moist lowland forest, plantations

IUCN habitat categories Site designations

Ape status

A 2017 survey revealed an enormous increase in population size in 15 years, from 313 to 1,570 orangutans (Simon, Davis & Ancrenaz 2019). The population has remained sparse and dispersed over a large area. These higher densities may reflect immigration from adjacent land areas where there has been substantial clearance of forest between the two surveys. The larger population estimate was also due to more intensive survey efforts, and a substantial but scattered orangutan population was probably underestimated in the past (Simon, Davis & Ancrenaz 2019).

Table 2. Ape population estimates in Imbak-Kalabakan

Species	Year	Abundance estimate (95% CI)	Density estimate [ind./ km²] (95% CI)	Area	Method	Source
Pongo pygmaeus morio	2002-2003	262(80–860)	0.06 (0.02–0.19)	Imbak-Kalabakan, Production Forest	Aerial survey	Simon, Davis & Ancrenaz 2019
Pongo pygmaeus morio	2017	876 (579–1323)	0.33 (0.22–0.50)	Imbak-Kalabakan, Production Forest	Aerial survey	Simon, Davis & Ancrenaz 2019
Pongo pygmaeus morio	2002-2003	51 (17–166)	0.06 (0.02–0.19)	Imbak-Kalabakan, Protected Forest	Aerial survey	Simon, Davis & Ancrenaz 2019
Pongo pygmaeus morio	2017	694 (458–1051)	0.32 (0.21–0.48)	Imbak-Kalabakan, Protected Forest	Aerial survey	Simon, Davis & Ancrenaz 2019

Threats

Habitat fragmentation and conflicts with people are the major threats to orangutans in the region (SWD 2020).

Table 3. Threats to apes in Imbak-Kalabakan

Category	Specific threats	Threat level	Description	Year of threat
1. Residential & commercial development		Unknown
2. Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	High	Forest loss and fragmentation due to conversion of forest to agricultural land. In Sabah, palm oil accounted for 60% of forest conversion between 1973 and 2015 (SWD 2020).	Ongoing (2020)
	2.2 Wood & pulp plantations	High	Plantations of Sabah Softwoods Berhad (SSB), an industrial tree plantation and oil palm plantation company, are situated within the Kalabakan landscape (Phaik Imm et al. 2021).	Ongoing (2021)
3. Energy production & mining		Unknown
4. Transportation & service corridors	4.1 Roads & railroads	Present, but threat severity unknown	Roads, bridges, dams, and railways split populations into smaller subpopulations and give access to poachers and lead to human encroachment (SWD 2020).	Ongoing (2020)
5. Biological resource use	5.1 Hunting & collecting terrestrial animals	High	Hunting due to conflict and for bushmeat (SWD 2020).	Ongoing (2020)
6. Human intrusion & disturbance		Unknown
7. Natural system modifications		Unknown
8. Invasive & other problematic species, genes, diseases		Unknown
9. Pollution		Unknown
10. Geological Events		Absent
11. Climate change & severe weather		Unknown
12. Other options		Absent

IUCN Threats list

Conservation activities

Table 4. Conservation activities in Imbak-Kalabakan

Category	Specific activity	Description	Year of activity
1. Residential & commercial development	Not reported
2. Agriculture & aquaculture	Not reported
3. Energy production & mining	Not reported
4. Transportation & service corridors	Not reported
5. Biological resource use	Not reported
6. Human intrusion & disturbance	Not reported
7. Natural system modifications	Not reported
8. Invasive & other problematic species, genes, diseases	Not reported
9. Pollution	Not reported
10. Education & Awareness	Not reported
11. Habitat Protection	Not reported
12. Species Management	Not reported
13. Livelihood; Economic & Other Incentives	Not reported

Conservation activities list (Junker et al. 2017)

Challenges

Table 5. Challenges reported for Imbak-Kalabakan

Challenge	Source
Not reported

Research activities

Documented behaviours

Table 6. Ape behaviors reported for Imbak-Kalabakan

Behavior	Source
Not reported

External links

Relevant datasets

A.P.E.S Portal

References

Simon, D., Davies, G., & Ancrenaz, M. (2019). Changes to Sabah's orangutan population in recent times: 2002-2017. PloS one, 14(7), e0218819. https://doi.org/10.1371/journal.pone.0218819
Sabah Wildlife Department (SWD). (2020). Orangutan Action Plan for Sabah 2020-2029. Kota, Kinabalu, Sabah, Malaysia.
Phaik Imm, C., Pei Hue, K., & Nathan, R. (2021). Can the Oil Palm Industry and Elephant Conservation Be Reconciled? A Case Study in Kalabakan, Sabah. Gajah, 53, 30-38.

Page completed by: A.P.E.S. Wiki team Date:22/11/2021

Imbak-Kalabakan

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