Big cats in Sundarbans: Male tigers at greater risk

With the intervention of humans, be it poaching or destruction of habitat, Bengal Tigers are now facing a new threat in the form of a dwindling male population.

The number of male tigers has come down alarmingly; so much so that the male-female ratio now stands at 1:10.

According to experts, the ideal male-female ratio is 1:3, but it so happens that the threats of extinction has affected male tigers more than the females.

The government is in the process of relocating tigers to up their population, particularly of male tigers.

“The number of male tigers is declining, which is very alarming. We have observed one male tiger against 10 females, but the ideal ratio is one against three. If in any case a male tiger dies or becomes a victim of poaching, female tigers in that area will face severe problems,” Md Jahidul Kabir, conservator of forests of the forest department, told The Daily Star yesterday.

He said the government is planning translocation of tigers to maintain the male-female ratio at 1:6.

The findings came up in a tiger census, which also showed that the number of Bengal tigers in the Bangladesh part of the Sundarbans has slightly increased.

The number rose to 114 in 2018, up from 106 recorded during the previous survey in 2015, an official involved in the latest census said, quoting the report.

Speaking to The Daily Star, Prof Md Anwarul Islam, WildTeam chief executive and a teacher of Zoology department at Dhaka University, said, “Age and sex ratios are very important for the healthy survival of any animal. One male tiger against ten female tigers is not a healthy population size. This is alarming. If there is no genetic diversity, population growth will suffer.”

Experts said the natural breeding process of tigers will be hampered if the male-female tiger ratios are not balanced.

The report said the assessed sex of the tigers, captured in photos in the Sarankhola block, demonstrates that tigers there have exceedingly skewed the sex ratio, with only one male in the entire sampled population.

“Usually, the roaming range for male tiger is more than the female tigers. So, the male tigers probably became victims of poaching,” said Dr Monirul H Khan, renowned tiger researcher and professor of Jahangirnagar University’s Zoology Department.

He also said the natural breeding process of tigers will be hampered if numbers of male tigers decrease.

The report on the census titled “Second Phase Status of Tigers in Bangladesh Sundarbans 2018” was recently released.

The census on the critically endangered species was conducted dividing the Sundarbans into three areas -- Khulna, Bagerhat and Satkhira.

The census in Satkhira was conducted in 2017. The following year, the census was carried out in Khulna and Bagerhat.

Forest officials said they conducted the camera trap census in 1,659 square km of core tiger population areas in the Sundarbans.

Of the total area, 1,208 square kilometres is in Satkhira, 165 square kilometres in Khulna and 286 square kilometres in Sarankhola, Bagerhat.

Forest officials installed 491 cameras on trees at 239 points of the Sundarbans and collected 2,500 images of tigers during a 249-day survey.

The survey results also showed that Sarankhola block has the highest density of tigers whilst Khulna has the lowest.

“A relatively low density of tigers in the Khulna block almost corresponded to the previous estimate of 2015. The exceedingly lower density of tigers in this region should be carefully taken into account in future protection management,” the report said.

It also said there might have been serious negative impacts of unprecedented human intervention by fishers in Dubla, Alorkol, Narikelbaria, etc, on tigers, its preys and their habitats.

Experts said the reason behind the scenario is that human intervention is higher in Khulna than in Satkhira. 

They also said protecting deer in the Sundarbans and reducing the movement of people would change the situation.

Dr Monirul, however, said tiger concentration will be more in the places where the number of their preys is higher.

Forest officials said the activities of bandits and poachers have seen a decline in recent times, following the introduction of smart patrolling, which has ensured safe movement of the tigers.

Officials data showed that after 2015, an average one tiger is killed every year. In 2015, the number was three.

“Our serious concern is that such a low density of tigers in the Khulna block appeared in both assessments. From the very low detection of tigers in this sanctuary, we suspect that this area of the Sundarbans might have either suffered from severe tiger and/or prey poaching, or their habitat has undergone significant degradation,” the report said.

International Tiger Day is observed on 29 July every year to raise awareness on the conservation of tigers and to promote the protection of their natural habitats.