Sungai Palin watershed

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Summary

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• Northwest Bornean orangutans (Pongo pygmaeus pygmaeus) are present in the Sungai Palin watershed.
• The population size is unknown.
• The orangutan population trend is decreasing.
• The size of the site is 321.28 km².
• Key threats to orangutans are road building, forest degradation and logging.
• Conservation activities have focused on community-based forest management.

Site characteristics

The protected areas of Danau Sentarum Wildlife Reserve and Betung Kerihun National Park, in the upper Kapuas watershed, were home to relatively large populations of the Bornean orangutan until the 1990s; from 1973 to 1997 almost 30% of habitat disappeared in and around Danau Sentarum Wildlife Reserve (Yanuar et al. 2020). Orangutans are still encountered in the unprotected areas of Sungai Palin and Nanga Awen, which lie between Danau Sentarum Wildlife Reserve and Betung Kerihun National Park (Yanuar et al. 2020).

Table 1. Basic site information for Sungai Palin watershed

Species	Pongo pygmaeus pygmaeus
Area	321.28 km²
Coordinates	Lat: 0.946904 , Lon: 112.661879
Type of site	Non-protected area
Habitat types	Subtropical/tropical swamp forest, Wetlands (lakes, rivers, streams, bogs, marshes)
Type of governance

Types of sites Governance types Habitat types

Ape status

A survey conducted in 1991 in Nanga Awen, c. 20 km away from Sungai Palin in the same landscape, recorded orangutan nests along three transects (1.0–1.2 km long, with a total length of 4.3 km). The estimated density was 2.62 (95% CI:1.02-6.72). In comparison, the density for Sungai Palin in 2017 was slightly lower (1.29 individuals/sq.km) (Yanuar et al. 2020).

Table 2. Ape population estimates reported for Sungai Palin watershed

Species	Year	Occurrence	Encounter or vistation rate (nests/km; ind/day)	Density estimate [ind./ km²] (95% CI)	Abundance estimate (95% CI)	Survey area	Sampling method	Analytical framework	Source	Comments	A.P.E.S. database ID
Pongo pygmaeus pygmaeus	2017			1.29 (0.51-3.25)		Sungai Palin watershed	Line transects		Yanuar et al. 2020	Survey effort:4.5 km. 76 nests were observed.

Sampling methods Analytical frameworks

Threats

Orangutans at the site have been mainly threatened by logging, forest degradation and lack of connectivity between forest remnants. A major threat is also the building of new roads (Yanuar et al. 2020).

Table 3. Threats to apes reported for Sungai Palin watershed

Category	Specific threats	Threat level	Description	Year of threat
4 Transportation & service corridors	4.1 Roads & railroads	High (more than 70% of population affected)	Construction of new roads in the area (Yanuar et al. 2020).	Ongoing (2020)
5 Biological resource use	5.3 Logging & wood harvesting	Present (unknown severity)	Habitat degradation due to logging; since 2003 a logging concession in the area of the Nanga Lauk village has been inactive (Yanuar et al. 2020).	2003

Threats

Conservation activities

Although protection of the site's forests are under the jurisdiction of the district forestry agency, they are managed by the local community as the Nanga Lauk Village Forest. The community is allowed to only extract non-timber forest products. Including the local community in the management of the forest has helped to protect the orangutans, as evidenced by the fact that logging ceased in 2003 (Yanuar et al. 2020).

Challenges

Table 5. Challenges reported for Sungai Palin watershed

Challenges	Specific challenges	Source	Year(s)
	Not reported

Challenges

Enablers

Table 6. Enablers reported for Sungai Palin watershed

Enablers	Specific enablers	Source	Year(s)
1 Site management
2 Resources and capacity
3 Engaged community
4 Institutional support
5 Ecological context
6 Safety and stability

Enablers

Documented behaviours

Table 7. Behaviours documented for Sungai Palin watershed

Category	Behavior	Observation type	Prevalence	Observation dates	Source	Habituation	Species	Comment
	Not reported

Behaviours

References

Yanuar, A., Fehse, J., Chivers, D., & Sugardjito, J. (2020). New estimates of orangutan density in Sungai Palin watershed, Kapuas Hulu, West Kalimantan, Indonesia. Oryx, 54(6), 763-766.

Page created by: APES Atlas Team Date: 2021-10-25