Wildlife & Biodiversity

Climate change to force mass migration of venomous snakes, increase poisoning in people, cattle

Models estimate some species may lose over 70% of their habitat while others gain over 250% 

By Himanshu Nitnaware
Published: Thursday 09 May 2024
The United States, northern Europe and Southeast Asia will see an increase in snake population. Photo of a venomous bush viper: iStock

Climate change may impact the geographical distribution of venomous snakes, causing mass migration of several of these species, a new report showed.

Many countries are expected to see loss and gain of venomous species owing to biodiversity and habitat loss, leading to increased envenomation that is poisoning by reptiles, snakes or insect bites, of humans and domestic animals, the scientists noted. 

They studied the geographical distribution of 209 medically important venomous snake species identified by the World Health Organization (WHO). The findings were published in Climate change-related distributional range shifts of venomous snakes: A predictive modelling study of effects on public health and biodiversity, published in the journal Lancet Planetary Health. 

Apart from its medical usage to prepare antivenoms and treatment of other diseases, snakes play an ecosystem function by predating on mammals, birds and other snakes for their dietary needs. 

The researchers further modelled their migration towards favourable climatic conditions with respect to climate change by 2070.

Loss of venomous snakes will be observed from the Amazon in South America and South Africa, the authors of the report warned. On the contrary, the United States, northern Europe and Southeast Asia will see an increase in snake species population.

By 2070, bush vipers, ottoman vipers, field’s horned vipers, rainforest hognosed pitvipers, Brazil's lanceheads, elegant pitvipers, desert death adders and pygmy copperheads will lose over 70 per cent of their habitats, the prediction model showed.

Every year, venomous snakes bites impact 1.8-2.7 million people worldwide, causing about 0.13 million deaths and about 400,000 amputations, leading to life-changing disabilities, according to WHO. Snakebites are a neglected tropical disease that needs highest priority, the United Nations health agency noted.

On the contrary, about 50 per cent of species such as rhinoceros viper and asp viper are expected to see a jump of 251 per cent and 136 per cent increase in their potential habitable areas. It also noted that horned viper will see a 118 per cent increase in its area.

Countries with lower gross domestic product and richness in livestock, extensive agricultural area and high population density such as Bangladesh, Nepal and Pakistan in Asia will see an increase in snake population, the researchers underlined.

In Africa, Uganda and Kenya are expected to see this trend. Moreover, agricultural areas in India, Bangladesh, Thailand, Uganda, Kenya, Camerron, Lithuania, Liberia and Ukraine have become more snake-rich.

Countries such as Somalia, Kenya, Mauritania and Mali are expected to have impact of venomous snake bites on its high cattle population. 

China, Myanmar and Nepal are estimated to gain four new snake species each. In Africa, the trend has been projected for Niger and Namibia. 

The study noted that species particularly from the families Elapidae and Viperidae have the potential to move to 300 metres a day, which add up to over 100 km a year. If the trend continues, the range would increase by 5,000 km over the next 50 years, the analysis showed.

The scientists predicted that such geographical distribution changes and alteration of ecosystem dynamics, especially in the rainforests that have highest diversity of venomous snakes, would affected potentially suitable areas and population reduction or extinction. 

The study pointed out that events such as floods during monsoon, may exacerbate the incidences of snakebites.

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