Climate change driving rural-urban migration of snakes

Marko Phiri

It has been an unprecedented snake season in Zimbabwe, as unusually high temperatures have driven the slithering cold-blooded reptiles into human-populated areas.

The result has been record snake bites, with 141 reported in one week in January as climate change drives and upends health narratives in a country where hospitals and clinics lack life-saving antivenoms.

Zimbabwe’s health system has been deteriorating for years, with hospitals lacking life-saving drugs, and there are concerns that the number of snake bites and fatalities could be underreported as some cases occur in remote rural areas where there are no clinics.

Catastrophic change

Zimbabwe has experienced unusually high temperatures recently and an extended dry season as it grapples with a climate-induced drought.

“Humans are not the only species impacted by the climate crisis. The world’s wildlife and habitats are also facing profound, sometimes catastrophic, change,” said Washington Zhakata, Climate Change Management director in the Ministry of Environment, Water and Climate. “Ecosystems are gradually becoming uninhabitable for certain animals, forcing wildlife to migrate outside their usual patterns in search of food and livable conditions.”

The World Health Organisation has raised concerns that little is understood about climate change, venomous snakes, and their impact on human populations.

“Humans will change farming practices”

“Climate change will only exacerbate the issue by affecting where, when, and how snakes share space with people. This happens because snakes will shift their distributions as temperatures rise and extreme events become more common,” the WHO says in a January update.

“Humans will change farming practices, and there will be greater pressures to migrate or be displaced. As a result, human–snake contact and conflict are expected to become more pronounced or frequent in some regions.”

In Zimbabwe, most reported snake bites occur in rural farming communities. According to the Zimbabwe Parks and Wildlife Management Authority, the country is home to eighty types of snakes, six of which are considered deadly.

Experts say the loss of habitat, exacerbated by extended high temperatures and dry seasons, has forced small animals hunted by snakes to move further. This, in turn, has forced dangerous snakes to look for food in areas occupied by humans.

Zimbabwe’s snake season usually lasts between September and March, months that typically cover the rainy season. However, the long dry seasons have upset that cycle, resulting in snakes changing what is thought to be their natural movement and hunting behavior.

Human-wildlife conflict

“There suddenly appear to be snakes all over the place,” said Titus Ndlovu, a resident of  Bulawayo, Zimbabwe’s second-largest city. “I don’t know what it is, but these snakes are basking everywhere. We fear for our children.”

This means city residents have not been spared and are also experiencing human-wildlife conflict, which is traditionally seen as a problem only in rural areas.

“Temperature may affect snakebites through human behavior or snake behavior; snakes are ectotherms, meaning outdoor temperatures influence their internal body temperature and thus their behavior,” say researchers in a paper published in 2023.

Livestock compete with wildlife

While some researchers have not seen an obvious or direct link between climate change and snake bites, they acknowledge the impact of shrinking natural habitats on human-wildlife conflict.

“I am not sure about any link between snake bites and climate change, but yes, climate change is exacerbating human-wildlife conflict,” said Nikhil Advani, the World Wildlife Fund‘s senior director for wildlife and climate resilience.

“In many parts of sub-Saharan Africa, for example, during drought, people and their livestock compete with wildlife for diminishing pasture and water sources.”

Marko Phiri is a Zimbabwe-based journalist writing on the intersection of climate change and development in Africa. This was first published on Alliance for Science