An endangered species of monkey, found only in Assam and parts of Bhutan, has a far-from-golden trait — forced abortion.
Primatologists have observed that the Gee’s golden langur (Trachypithecus geei), endemic to the semi-evergreen and mixed-deciduous forests straddling India and Bhutan, induce stillbirth of babies killed inside the womb of females, besides practising infanticide.
Foeticide in the natural world is, however, quite different from one of the first cases of abortion due to electrocution of a female in Nayekgaon near Kokrajhar, about 225 km west of Guwahati, on June 5, which happened to be World Environment Day. Largely encroached upon, Nayekgaon is one of 11 fragmented habitats of the golden langur, excluding the 500 sq. km. Manas National Park.
“Golden langurs use the upper canopy of trees to travel but the three-phase electric wire came in the female’s way,” said Daoharu Boro, a wildlife veterinarian.
The female had fallen about 15 feet after the wire burnt her limbs and chest. She died within 24 hours of delivering a still baby due to the impact.
Killer wires
The golden langurs in Assam are hemmed in by three rivers — Brahmaputra in the south, Manas in east and Sonkosh in west. Their northern limit is the range of hills in Bhutan up to 2,400 metres above sea level.
Primatologists say their habitat in Assam has fragmented drastically in the last 30 years but electric wires began to be strung through them, mostly after a thrust on rural electrification six years ago. Many villages on the fringes of notified jungles and settlements in encroached areas have been beneficiaries.
“Unlike the Hanuman langurs elsewhere, golden langurs are yet to adapt to the wires, and they use the upper canopy of trees to travel because of fear of dogs on the ground. Electrocution has also killed the monkeys in groups,” said Jihusuo Biswas of Guwahati’s Primate Research Centre.
Obstructions such as wires, and gaps in the forest due to felling, have increased the threat of inbreeding among golden langurs. “This is happening in the highly fragmented Kakoijana forest. This is not a serious issue now, but could explode into a major problem later,” he said.
Genetic insurance
Avoiding inbreeding is the reason why golden langurs live in specific groups, Mr. Biswas said.
The groups are primarily of two types — one is all-male and the other is bisexual, which in turn has three categories.
“A bisexual group can have one male with a harem of four-five females, two males with multiple females and multiple males with multiple females. But in such groups of two or more males, only the dominant male can access the female,” he said.
Forced abortion and infanticide happen when a new male takes over. He often kills the baby of a lactating female or hits the abdomen of a female impregnated by the deposed male till the point of abortion.
“A dominant male knows he can access females for three years at most and wants to control the females to ensure as many of his progeny [as possible] before being ousted to be solitary or create space in an all-male group,” Mr. Biswas said.
Golden langur females maintain a gap of at least two years between babies. This gap can increase to three years depending on habitat conditions, which is a cause of concern for primatologists.
“They survive mostly on a variety of juicy leaves. But fragmentation of forests and selective logging is making their food scarcer,” Mr. Biswas said.
In 2019, Bhutan recorded a drop of 62% in the population of golden langurs over the 2009 census. The recorded estimation in Assam in 2009 was 5,140. This year’s census could not be completed due to the COVID-19 lockdown.
