On January 12, a 15-year-old one-horned rhino was found dead near the Giddheni Post inside the Chitwan National Park, home to the largest number of rhinos in the country. The pachyderm had died due to a chronic disease, leaving infection in its lungs and abdomen.

The death of the endangered rhino was not the first in the current fiscal year 2018-19. It was the 23rd such death recorded by the park, which is witnessing a troubling rise in rhino deaths.

Most of these rhinos were between 15 and 30 years of age and at least nine of them have been below 25 years. The average lifespan of a rhino is 40 years. The sudden surge in deaths of one-horned rhino inside the park has become a cause for concern among conservationists following a great stride in rhino conservation efforts, with a substantial reduction in poaching.

According to the 2015 count, Nepal is home to 645 rhinos—605 in Chitwan, 29 in Bardia National Park, eight in Shuklaphanta National Park, and three in Parsa National Park. The number of rhinos, which fell sharply in the 1950s and 60s, started to rebound after the establishment of the Chitwan sanctuary in 1973.

If the current rate of rhino deaths continues, which looks an all-time high since the country started recording deaths, the country is about to lose the highest number of rhinos in a year, even surpassing the tally of the decade-long armed struggle, when poaching was rampant.

According to park officials, now rhinos are dying natural deaths. While not a single rhino has been poached this year, all of them have died due to territorial fighting, drowning, old age, pain during childbirth and diseases.

This year alone, 11 rhinos died of old age, five due to territorial clashes, two died after drowning in swamps while others perished because of similar causes. “All of them have died due to natural factors that occur in the wilderness, as there has been zero poaching this fiscal year,” Bed Kumar Dhakal, chief conservation officer at the Chitwan National Park, told the Post.

Dhakal, however, acknowledged that the growing death rate worries the authority.

Officials also attribute factors including the rising number of rhinos in the park while the habitat remains limited as before to the rising fatalities.

“Last year’s flood had forced rhinos to move from the eastern area to the western side of the park, increasing population density in that particular stretch. This resulted in territorial fights and injuries. This could have led to more deaths,” said Gopal Bahadur Ghimire, information officer at the Chitwan Park. But he was quick to add that it was only a speculation as he was not in a position to pinpoint the cause(s) of deaths.

Shrinking habitat also results in fighting between rhinos and high concentration of adult rhinos, which have now aged, can be other causes of death, suggests Dr Kamal Gaire, a former senior veterinarian with the park.

However, the sudden increase in rhino deaths even due to natural causes is a phenomenon seen in the last three years only. In the last FY 2017-18, a total of 26 rhinos died in the park, followed by 25 deaths, including one poaching incident, in the FY 2016-17.

Before this unprecedented surge since mid-2017, the number of deaths due to natural causes would be around 15 annually.

In the last 20 years, a total of 433 one-horned rhinos have died inside the Chitwan National Park due to various reasons. Of the total deaths in the period, 157 rhinos were killed by poachers during the armed conflict that ended in 2006.

A separate study titled “Chitwan National Park Rhino Mortality Report (2018)”, conducted by the Veterinary Initiative for Endangered Wildlife, says, “141 documented rhino deaths from 2004-2017, with 111 (79 percent) deaths due to unknown/natural causes and 30 (21 percent) due to poaching.”

The report had also concluded that the park had seen a dramatic rise in rhino mortality in the last three years compared to the previous decade. The report also recorded that among the 141 rhino deaths, the highest (114) was of adult (older than five years), followed by sub-adults (4) and calves (23).

The government record puts deaths into two broad categories—natural/unknown and poaching. As per its category, all deaths including territorial clash, drowning, injuries, old age, diseases and everything other than poaching are defined as natural.

When approached about the unknown deaths, park officials said unknown categories include “deaths which were not identified”.

“Sometimes dead rhinos are found after months with most of their parts decayed, making it difficult for examination. As their parts were found to be intact, we know they were not poached,” added Ghimire. “In most of the cases, post-mortem is conducted on the site by veterinarians, but after failing to find any particular cause of death, these cases are declared reason unknown.”

The mortality report which had identified haemorrhagic diseases, anthropogenic causes, gastroenteritis, respiratory disease, sepsis, dystocia/abortion, poaching, and old age, among other factors, also pointed out that the causes of death could not be determined in most cases and were attributed to unknown causes. However, there were different identifiable categories of disease according to gross postmortem findings. It also said there were very few laboratory-based diagnoses.

“These unknown causes don’t mean the deaths are a mystery,” Gaire said. “Sometimes the existing laboratory set-up cannot perform specific diagnosis when it comes to identifying disease pathogens. With the minimum lab support available, it is difficult to give confirmatory results at times.”

According to Gaire, identifying the causes of deaths of rhinos, whose bodies are found after months of dying, becomes difficult and hence enlisted as unknown.

The rhino mortality study reports that there were 41 deaths due to unknown reasons out of the total 141 deaths between 2004 and 2017.

Following the recent high mortality rate of rhinos in the park, the Department of National Park and Wildlife Conservation has formed a committee to study the causes of deaths.

“The team of experts will find out what is killing our rhinos and the impact of other factors like habitat loss, climate change and other anthropogenic activities on rhinos. We are working to improve our laboratory set-up soon,” said Man Bahadur Khadka, director general with the department.

Khadka added that the department had also started measuring the carrying capacity of the Chitwan National Park which currently has 605 rhinos concentrated in an area of 932 square kilometres. “While the number of rhinos has gone up over the years, the park has only 952 hectares of grassland for the whole rhino population.”