gAnesh Pant worries about the future. As he rejoices at the astonishing conservation achievement that has seen the number of great one-horned rhinos in Nepal rise from 100 in 1965 to 752 in 2021, he wants to be sure the success will continue.
Before the 1950s, up to 1,000 rhinos roamed the grasslands and forests of Nepal. But by 1965 rampant hunting, poaching and land use changes had brought the species to the brink of extinction in the country. Then the national park was established in 1973 and through concerted conservation efforts, the rhino population began to rebound.
Today, Chitwan National Park is home to the second-largest concentration of one-horned rhinos after India’s Kaziranga National Park, with the two parks accounting for 70% of the species’ global population. Besides playing a key role in the ecosystem, Chitwan’s rhinos attract large numbers of tourists every year, contributing significantly to the country’s economy. In 2019, there were 185,000 foreign visitors to the park.
But the greater one-horned rhinoceros is still listed as vulnerable by the International Union for Conservation of Nature (IUCN), and a new threat has emerged. While there have only been around five confirmed poaching deaths between 2016 and 2020, more than 100 rhinos are believed to have died of natural or unknown causes. “Poaching was once the cause of rhino mortality. But in recent years, the government has done a great job of protecting rhinos from poaching,” says Pant, a conservation officer working for the Department of National Parks and Wildlife Conservation in Nepal.
“At this stage, we cannot say that [these deaths are] solely because of the impacts of climate change,” says Pant, who is doing a PhD at the University of Southern Queensland, Australia. But he believes the climate crisis could be one of the underlying causes. Pant and a team of researchers have developed a set of 21 indicators to assess the vulnerability of Nepal’s rhinos to climate change. They concluded that they were “moderately vulnerable” to the impacts of global warming, mainly due to the likelihood of invasive species and extreme flooding in the rhino’s core habitat, as well as habitat fragmentation, droughts and forest fires.
“I tried to look at the likely change in rhino habitat in Nepal over the next 50 years under different climate change scenarios,” he says. “And to know what the adaptation measures would be – to build rhino resilience in the context of likely climate change impacts.”
Rhinos are a highly adaptive species, hence their categorization as moderately vulnerable. “That means it’s not threatened with immediate extinction due to climate change, but we need to take that into account for now if we want to maintain the population for the long term,” Pant says.
Wendy Foden, conservation biologist, agrees: “We are currently experiencing the fastest rate of climate change in 65 million years. If conservation planning efforts are to remain relevant and strategic, they must include the best available scientific data on anticipated future impacts.
Recent studies have shown that several species of animals are already feeling the impact and reacting by shifting their habitats and even developing larger appendages or beaks, legs and ears to better regulate their body temperature in some cases. However, predicting the effects of the climate crisis on biodiversity is a challenge, partly due to the lack of long-term observational data.
“It would be very unwise to plan species conservation actions until you have carefully assessed what can go wrong for that species, the mechanisms of potential impacts, its sensitivity to them and whether it is likely to be able to adapt. itself,” says Foden, who chairs the IUCN Species Survival Commission’s Climate Change Specialist Group and led the development of IUCN’s guidelines for assessing the vulnerability of species to climate change.
“These provide the foundations from which to build strong conservation plans. Thus, in most cases, analysis of vulnerability to climate change is imperative for species conservation planning.
Pant’s research examined the one-horned rhino’s vulnerability to the climate crisis based on its sensitivity, exposure and adaptive capacity. Sensitivity is the extent to which a species is likely to be affected by climate change; exposure is the extent to which their physical environment will change; and adaptive capacity is their ability to overcome the negative impacts of climate change.
While one-horned rhinos did well in the climate change vulnerability analysis, climate change is already threatening the rhino population in Chitwan National Park. The species depends on a certain level of annual flooding to maintain its habitat.
But in recent years, extreme flooding has hit the park on several occasions, carrying rhinos downstream to India and bringing debris and rubbish upstream. Drought also occurs more often, reducing the number of ponds in which rhinos wallow to regulate their temperature. Invasive species such as bitter vine (Mikania micrantha), and Chromolaena odorata, a flowering shrub also known as siamese grass, is spreading at an alarming rate, encroaching on grasslands that are the primary habitat of rhinos. Global warming is expected to exacerbate extreme floods and prolonged droughts, as well as the rapid growth of invasive species in the future.
According to Naresh Subedi, conservation program manager at Nepal’s National Trust for Nature Conservation, better population and habitat management is crucial in tackling the climate crisis. “Currently, our rate of increase in the rhino population is 5%, for example. If we maintain an annual rhino population increase of 8%, then even if we lose 3% of the rhino population through annual floods or weather-induced incidents, they will still be in a good position.
Pant agrees, noting that while flooding is only seasonal, maintaining suitable habitat year-round is essential to maintaining a healthy population. Another recent study by his team found that more than a third of rhino habitat in Nepal could become unsuitable within 50 years due mainly to climate change, but also to land use change.
Pant proposed seven adaptation measures to secure the future of the one-horned rhino, including: maintaining the ponds the rhinos need for wallowing; managing the impacts of flooding; creating “safe havens”; and the active management of habitats to provide a mosaic of grasslands and wetlands.
“We talk about adaptation because mitigation can take a long time and also depends on several factors,” says Pant. “It’s not in our control, so the only thing we can do is protect the rhino in these extreme conditions. This is our priority at the moment. »