style="text-transform: uppercase;">Kota Kinabatangan: Nearly one-half of all primate species are threatened with extinction, with habitat destruction serving as the key driver. Studies on the impact of habitat changes on primate populations are limited and often based on inferences because primates are long-lived mammals with slow life cycles, and generally respond very slowly to environmental changes.

Such information is, however, essential for developing effective management plans for long-term conservation.

A study, recently published in Oryx, and led by a team of researchers from Chubu University and Hokaido University (Japan), Sun Yat-sen University (China), Living Landscape Alliance, the NGO HUTAN, Sabah Wildlife Department and Danau Girang Field Centre (Sabah), assessed the population trends of proboscis monkeys over 10 years in the Lower Kinabatangan floodplain.

Comparisons of directly counted 2004 and 2014 population sizes revealed subtle changes, where population densities fluctuated but had neither monotonically increased nor decreased, but with significantly reduced group sizes.

"Proboscis monkeys are endemic to the island of Borneo. They are classified as 'endangered' according to the IUCN Red List of Threatened Species and listed under Appendix I of Convention on International Trade in Endangered Species (CITES).

"They are also a Totally Protected species in Sabah under the Sabah Wildlife Enactment 1997," said Sabah Wildlife Department Director Augustine Tuuga.

"Despite these levels of protection, lowland swamp forest habitats that are important for this species are still decreasing, mainly through forest conversion to oil palm plantations," he added.

"One reason for the relatively stable population could be that there were only minor losses of forest along the rivers where proboscis monkeys are generally found. These reduced losses were the result of increased protection measures for these habitats in the Kinabatangan floodplain over the past decade," said Dr Marc Ancrenaz, Scientific Director at the NGO Hutan.

"Indeed, our analysis of habitat changes showed that within protected reserves, there was relatively little forest loss in the potential range of the proboscis monkey, which mainly lies within an 800m buffer from riverbanks.

"This suggests that the protection of riparian forests can contribute immensely to the sustainability of proboscis monkeys within these important habitats.

"However, larger losses of interior forests meant that habitats had generally become more degraded and fragmented, and this could have contributed to reduced group sizes and limited population growth," he added.

"Although the protection of forests within the proboscis monkeys' range had proved effective, this was however, not the case in unprotected forests, where 12pc of the forest was lost during this time and could eventually lead to 22.7pc of the population being threatened, said Dr Benoit Goossens, Director of Danau Girang Field Centre and Reader at Cardiff University.

"At least a third of these forests has been allocated for oil palm cultivation but much of these were unsuitable for oil palm because they are subject to seasonal or daily inundation. Further efforts must be undertaken to more effectively conserve high value habitats and to restore riparian areas that could go a long way into ensuring the long-term viability of this species," concluded Goossens.