Montane regions in Java, Indonesia, harbour a wealth of biodiversity, including many endemic and threatened species and some of the island’s last remaining forest. However, many areas of montane forest are exploited unsustainably and are unprotected, meaning they are not formally designated as protected areas or managed by communities or conservation organizations. Many songbirds are trapped in montane areas. They are sold in bird markets, where they are kept as caged pets in both rural and urban areas or used in hugely popular, and profitable, bird singing competitions. This bird trade has fuelled the trapping of some formerly widespread species, bringing them to the brink of extinction on the island. Within this context, we obtained a grant from Rainforest Trust, EAZA’s Silent Forest campaign, and Chester Zoo to survey biodiversity across montane sites in West Java, and Gunung Slamet in Central Java, as part of a joint project with Burung Indonesia, a bird conservation NGO and BirdLife partner, to propose new conservation areas in association with the Indonesian Ministry of the Environment.

Javan Gibbon Hylobates moloch.

Standing at 3,432 m, Gunung Slamet is the second highest mountain on the island and is mostly forested above 800 m. Here, we surveyed birds, amphibians, terrestrial mammals, primates and basic habitat structure using audio recorders, camera traps, walking transects and ad hoc searches.  These confirmed the presence of threatened species such as the Javan gibbon, Javan surili, Javan leopard and the heavily persecuted endemic rufous-fronted laughing thrush, not recorded for decades. Newly documented mammal records included the Critically Endangered Sunda pangolin, heavily threatened by illegal trade.

Songbird market in Purwokerto, Java, Indonesia.

On Gunung Slamet, species such as the white-bellied fantail or Javan scimitar babbler should have been common but were rarely recorded on our transects. However, species such as the Javan trogon were fairly common on Gunung Slamet and seem to be doing better than previously thought across several West Javan mountains. The same is true for the rufous-fronted laughing thrush, which, although much sought after by trappers, was also found at several locations on Slamet, but  possibly now in smaller flocks than previously. Songbird trapping causes biodiversity loss in ways that we are yet to fully understand. Other research at Manchester Metropolitan University has shown the huge scale of the cage bird trade on Java, much of which involves wild-caught songbirds. Unlike deforestation, where habitat is lost, removing species from ecosystems can have knock-on effects that may not be clear for many years to come, but will undoubtedly disturb the system’s delicate functioning.

Camp site at Ketenger, at 1,730 m.

We worked with local guides from villages near our camps on Gunung Slamet, many of whom had a wealth of knowledge about the forest, especially birds, and provided us with detailed information about behaviour, breeding and songs. Often, they admitted to having trapped birds in the past, and it may well be that some still trap them to supplement their income. But even if they have links to the bird trade, they are also well placed to protect forest resources and, with incentives to do so, they could collaborate with regional authorities to guard forest resources and manage any permitted use sustainably. Incentives may also come from the village communities themselves—we heard of villages where trapping, especially by people from outside the community, was prohibited by the community. The best form of protection for Gunung Slamet may come from a combination of measures, implemented at different levels, from local and regional government, but undertaken with the support of those villages that directly depend on the mountain for their livelihoods.

Preparations in Ketenger village prior to first field trip.

Gunung Slamet was the first mountain we surveyed during our project and it quickly became clear that it is an obvious candidate for increased protection. However, the question of which kind of protection status and how this would be implemented is complex. Our article presents the findings of our preliminary biodiversity survey and proposes some forms of protection. The next stages in improving the management of Gunung Slamet will be part of a joint decision-making process, currently underway in the second phase of the Rainforest Trust project, led by Burung Indonesia. This stage will entail working with local communities and regional authorities to understand their needs and perspectives, while attempting to provide the best form of protection for Gunung Slamet, which is an important source of water for towns and villages in the region. We hope our efforts will help increase biodiversity protection on Java, but we are also conscious that the biological aspects are just one piece of a complex puzzle where social, economic and political factors are all at play.

Sunrise view of Gunung Slamet mountain summit.

All photos: Gabby Salazar

The open access article Biological richness of Gunung Slamet, Central Java, and the need for its protection is available in Oryx—The International Journal of Conservation.

Christian Devenish is a post doctorate researcher at Manchester Metropolitan University and the University of East Anglia working in spatial ecology, particularly in exploring the occurrence and abundance of species and incorporating statistical modelling to establish patterns of occurrence and abundance and relationships with environmental factors.