Habitat loss drove long-tailed macaques extinct in Bangladesh, experts say

Sep 29, 2023

  • Clearing of mangrove forests along the Naf River in southern Bangladesh was the main driver for the extinction of the long-tailed macaque in Bangladesh, according to longtime experts on the species.
  • From an estimated 253 of the monkeys in 1981, the population plunged to just five individuals in 2010, then three in 2012, before it was declared extinct in the country in 2022.
  • Experts attribute this trend to the clearing of mangroves for shrimp farms, farmland, refugee camps, and settlements.
  • Though one of the most widely distributed monkey species in the world, the long-tailed macaque faces severe threats throughout its range, and since 2020 has seen its conservations status progressively worsen from least concern to vulnerable to endangered.

DHAKA — Experts point to habitat loss from a wide range of factors as the main reason the long-tailed macaque, one of the most widely distributed monkey species in the world, has gone extinct from Bangladesh.

The mangrove forests of the southern district of Cox’s Bazar once constituted the northernmost reach of the species’ range in Asia. Scientists recorded a population of macaques (Macaca fascicularis) in the Teknaf region of Cox’s Bazar in 1981, along the Naf River, estimating it at 253 animals.

Fast-forward to 2022, however, and an assessment by the IUCN, the global wildlife conservation authority, declared the species extinct in Bangladesh, with its global status worsening from vulnerable to endangered.

“The long-tailed macaque was found in the Naf River belt, but the species disappeared from the area due to habitat destruction caused by prawn culture,” M. Farid Ahsan, a professor of zoology at Chittagong University and co-author of a 2012 study assessing the species’ status in Bangladesh, told Mongabay.

His study found only one group of macaques — two adult males and one adult female — in the coastal forest belt near Teknaf Port during a survey carried out from July 2010 to February 2011. After that, no long-tailed macaques were seen in the coastal forest of the southeastern area or anywhere else in Bangladesh.

Ahsan and others blame the clearing of mangrove forests for shrimp farms, farmland and fuelwood as the leading causes of habitat loss of the long-tailed macaque. The 2012 study noted that these crab-eating monkeys preferred coastal mangrove habitats, but fishermen and fish buyers frequenting the area’s mud belt during low tide would disrupt the macaques’ feeding activities.

Residents would also graze their livestock in the macaques’ habitat, while an influx of Rohingya refugees from neighboring Myanmar settled temporarily in refugee camps in Cox’s Bazar, resulting in the clearing of macaque habitat.

Long-tailed macaques in the mangroves of Mu Ko Lanta Marine National Park, Thailand.
Long-tailed macaques in the mangroves of Mu Ko Lanta Marine National Park, Thailand. Researchers blame the clearing of mangrove forests for shrimp farms, farmland and fuelwood as the leading causes of habitat loss of the long-tailed macaque in Bangladesh. Image by Peter Prokosch via Flickr (CC BY-NC-SA 2.0).

The establishment of new settlements along the Naf River coastal belt and the construction of jetties also contributed to this destruction, the study said.

Md. Kamrul Hasan, a professor of zoology at Jahangirnagar University, said that although the mangrove habitats in Teknaf were destroyed very rapidly, the macaques didn’t shift to different habitats further uphill, suggesting the latter offered the monkeys even less in the way of food resources.

“The reason may be that more food was available in the mangrove habitat as compared to the hill range,” he said.

Hasan’s 2010 study of macaque populations in Bangladesh found just five of the animals in the region of the Naf River where Ahsan would later count just three.

“Those were the last population of long-trailed macaque spotted in Bangladesh,” Hasan said.

He added the monkey played in a vital role in maintaining the ecological balance of the mangrove forests where it occurred, until those forests were cleared for shrimp farms.

Long-tailed macaques are widely distributed across Asia, their range stretching today from Myanmar in the west to the Philippines in the east, and south to Indonesia. While habitat loss wiped it out in Bangladesh, the leading threats within many of these other countries also come from retaliatory killing of macaques seen as pests, and trapping for use in lab testing.

According to the IUCN, the global population of long-tailed macaques has declined by about 40% over the past 40 years, and will decline by at least 50% within the next 40 years. The 2022 assessment suggests that after Bangladesh, the species could next disappear from Laos, where its presence is listed as “uncertain.”

Banner image: A mother long-tailed macaque with her young in Djuanda Forest Park, West Java, Indonesia. Image by Rossche via Wikimedia Commons (CC BY-SA 2.0).

Endangered species listing of long-tailed macaques: ‘shocking, painful, predictable’ (commentary)

Citations:

Kabir, M. T., & Ahsan, M. F. (2012). The present status and distribution of long-tailed macaque Macaca fascicularis aurea (Mammalia: Primates: Cercopithecidae) in Bangladesh. Journal of Threatened Taxa, 4(1), 2330-2332. doi:10.11609/jott.o2808.2330-2

Hasan, M. K., & Feeroz, M. M. (2010). Distribution and status of long-tailed macaque (Macaca fascicularis aurea I. Geoffroy Saint-Hilaire, 1830) in Bangladesh. Journal of Threatened Taxa, 2(12), 1342-1344. doi:10.11609/jott.o2461.1342-4