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Bornean bantengs feeling the heat in logged forests, study finds

  • A recent study shows that Bornean bantengs in recently logged forests in Malaysia’s Sabah state have become less active during the daytime in response to the hotter temperatures brought on by there being fewer trees providing shade.
  • Banteng herds living in forests with more regrowth continue to be active throughout the day as they have more shade and refuge.
  • The paper’s researchers suggest that steps must be taken to reduce the stress upon bantengs, such as limiting disturbance during key times of activity and maintaining blocks of mature forest.

The endangered wild cattle of Malaysian Borneo have eased back on their daytime activities because of higher temperatures brought on by loss of forest cover — a finding that has important implications for the species’ well-being.

The findings, in a report published April 12 in the open-access journal PLOS One, showed that recently logged forests in Sabah state were hotter, reaching temperatures of up to 44 degrees Celsius (111 degrees Fahrenheit), for longer periods of time in the day than forests that had experienced regrowth for longer. This temperature differential, it turns out, affects the activity of the Bornean banteng (Bos javanicus lowi).

The researchers, from the Sabah Wildlife Department and the Danau Girang Field Centre (DGFC) in Malaysia, Cardiff University in the U.K., and the Leibniz Institute for Zoo and Wildlife Research in Germany, carried out the study from 2011 to 2013 in three secondary protected forests in Sabah: the Malua Forest Reserve, Maliau Basin Conservation Area Buffer Zones, and Tabin Wildlife Reserve.

Bantengs foraging in the early morning in an open degraded area. Image courtesy of Danau Girang Field Centre (DGFC).

Each of these areas has experienced extensive and repeated removal of timber, and each also have internal logging road networks with exposed and compacted substrate resulting from the use of heavy machinery. The last logging activities recorded in these areas occurred six, 17 and 23 years ago, respectively.

The paper found that banteng populations in the more recently logged forests tended to show reduced activity and to avoid degraded areas during the hot hours between dawn and dusk.

“[This is] possibly to avoid thermal stress which can be fatal [for the bantengs],” Penny Gardner, lead author and program manager of banteng research at the DGFC, said in a statement.

High temperatures are detrimental to warm-blooded animals like bantengs. They affect metabolic processes and physio-biochemical processes, increasing methane emissions and water intake, and decreasing urination, lactation and body weight, the researchers noted.

While cattle native to warm environments have adapted physiologically, the researchers suggested that these traits would not be sufficient to mitigate heat stress as the animals prefer to seek out the natural shade of trees.

Bantengs resting under dense canopy during the middle of the day. Image courtesy of Danau Girang Field Centre (DGFC).

Banteng populations living in forests with a longer period of regrowth continue to be active throughout the day, as they have more shade and refuge, the study found.

However, as their main food — grasses, ferns and shrubs — are commonly found on forest edges, the bantengs run a higher risk being hunted, said Benoit Goossens, a co-author of the study and director of the DGFC.

“Steps taken to reduce stress upon bantengs could include limiting disturbance during key times of activity and maintaining blocks of mature forest,” Goossens said.

He said these recommendations and others would be outlined in the Banteng Action Plan, currently being drafted by the Malaysian government.

Bantengs in Sabah have long been threatened by loss and fragmentation of habitat, as well as intensive poaching. They are considered the most endangered large mammal in the region, numbering fewer than 400 individuals across the whole of Malaysian Borneo. Scientists have warned that the species could go extinct within 20 years at the current rate of decline.

The banteng is a species in Sabah, and possession of the wild cattle or its parts can result in jail time and fines of at least 50,000 Malaysian ringgit ($12,840).

Still, Sabah is a global hotspot of forest degradation, due in large part to the oil palm and timber industries. In 2009, only 8 percent of protected areas there comprised intact forest that had not been logged since the 1970s.

A previous study showed that bantengs displayed signs of adaptability to post-timber harvesting conditions and could persist in commercial forests, frequently using old logging roads, access roads used by vehicles, and degraded open areas to forage and congregate.

Bantengs foraging in an open degraded area in the early hours of the day. Image courtesy of Danau Girang Field Centre (DGFC).

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