Are encounters with snakes rising in the UAE because of changing temperatures?

Reptiles are hibernating for shorter periods, say experts

Persian horned viper (Pseudocerastes persicus). Photo: Supplied by Johannes Els

Hajar saw-scaled viper (Echis omanensis). Photo: Supplied by Johannes Els

Zarudnyi’s worm lizard (Diplometopon zarudnyi). Photo: Supplied by Johannes Els

Persian horned viper (Pseudocerastes persicus). Photo: Supplied by Johannes Els

Hottentotta jayakari. Photo: Supplied by Johannes Els

Sindh saw-scaled viper (Echis carinatus sochureki). Photo: Supplied by Johannes Els

Tailless whip scorpion (Order Amblypygi). Photo: Supplied by Johannes Els

Arabian horned viper (Cerastes gasperettii gasperettii), a hornless specimen. Photo: Supplied by Johannes Els

Arabian horned viper (Cerastes gasperettii gasperettii) with horns. Photo: Supplied by Johannes Els

Sindh saw-scaled viper (Echis carinatus sochureki). Photo: Supplied by Johannes Els

Arabian thick-tailed scorpion (Androctonus crassicauda). Photo: Supplied by Johannes Els

Environment officers in Fujairah have been called into action 48 times this year to remove venomous snakes from gardens and vehicles in the emirate.

Authorities say the figures represent a rise in close encounters with the reptile over previous years.

A possible reason behind this, officials say, is the popularity of camping, because food left behind could be changing feeding patterns and leading to larger snake populations.

But climate change could also be influencing snake behaviour in the UAE, potentially causing them to be active at times of the year when they were previously dormant.

The UAE is home to 13 species of snake, four of which are venomous, and the reptiles are sometimes found in gardens or homes – particularly in newly built settlements and more remote areas.

Prof Salvador Carranza, of the Institute of Evolutionary Biology in Barcelona, said that such a pattern had been observed in Spain, and was likely to be seen elsewhere.

“If temperatures remain high during the winter months, in Spain and everywhere, reptiles remain active,” he said.

“If temperatures drop, reptiles retreat and hibernate. It is not necessary to do a study; it is something that is well-known and has been observed.

“The same reptile species can be active in one geographical area, and at the same time of the year inactive (hibernating) in another part of its distribution range. It just depends on the temperature, the weather.”

According to data published by the University of Edinburgh in Scotland, temperatures in the UAE are now around 1.8°C higher than they were in pre-industrial times, which may have affected the behaviour of reptiles, including snakes.

But Andrew Gardner, associate director for biodiversity conservation at Emirates Nature-WWF, does not think this is having a major impact on snake behaviour – at least for now.

“I would expect that warming climate will mean that snakes will become more active earlier in spring, but this is unlikely to be a major effect (yet),” said Dr Gardner.

Where are the snakes?

While it is possible that snakes in the Emirates may now be more active during cooler parts of the year, scientists say that there is no evidence that their overall distribution in the country has been affected by climate change.

Some mountain-dwelling species may have experienced changes, though.

“Climate change might have an important effect for animals that live high up in the mountains, with small distribution ranges,” said Prof Carranza.

Such species, he said, may be unable to move high enough to escape from the warmer temperatures caused by climate change.

Climate change could, in future, affect the reptiles’ distribution if it resulted in altered patterns of rainfall – including more rain in some areas, said Johannes Els of the Sharjah Environment and Protected Areas Authority.

“An increase in rainfall will have an impact on the long-term distribution range of species like the sand viper,” he said.

“That could reduce their distribution. They could move away from where there’s an increase in humidity or rainfall to areas where it’s drier.”

How dangerous are UAE snakes?

A major concern is the risk of being bitten, despite there being no reported snake bite deaths in the UAE for well over a decade.

Despite the low danger, medical attention should always be sought in the event of a bite.

Experts also say that anyone who encounters a snake should never attempt to attack or kill the reptile.

“Snakes in the UAE are not aggressive and do not attack and bite unless provoked,” said Dr Gardner.

“Generally, snake bites result from accidental walking on or close to a snake or from people trying to pick them up or kill them.

“Leave them alone and they will move away.”

Encounters tend to peak in April, May, September and October – when the weather is hot enough for snakes to be active, but also cool enough for residents to venture outside.

Globally, about 5.4 million people are bitten by snakes each year and the number of deaths is between about 81,000 and 138,000, World Health Organisation figures indicate.

Three times as many people suffer permanent disability or have to have an amputation, the WHO said.

Of the 13 snake species in the UAE, four are venomous, all of them vipers.

Vipers are characterised by having a thick body and a triangular head that is distinct from the neck.

Dr Gardner said that in the mountains in Oman, the frequency of snake bites goes up in the warmer months, as vipers are more active on warm nights in farms and wadis.

How does human activity impact snakes?

While snakes may in some circumstances pose a risk to people in the UAE, human activity is undoubtedly having a negative impact on the reptiles.

“Habitat loss and disturbance are much stronger drivers of changes in snake distributions,” said Dr Gardner.

The pattern is that as development increases, snake numbers tend to go down, said Prof Carranza.

“They kill snakes during development,” he said.

“If you tarmac a road, if you make roads, you make houses, you kill snakes.

“You move their sand, you move rubble, in the end you affect snake populations, up to the point they disappear completely.”

However, he said that during development, there would often be areas that were left undisturbed where snakes could remain.

“That’s why sometimes people keep encountering them in urban areas. People go for a walk in those patches,” said Prof Carranza.

Indeed, in areas surrounding the likes of new housing or industrial estates, snakes may appear more common because they have been pushed out of their habitat.

“This is temporary until the populations stabilise again,” said Dr Gardner said.

Mr Els said that the authorities in Sharjah received more call-outs about snakes from people living in new residential areas that “border natural landscapes”.

“There’s more frequent encounters than with people who live in old town areas,” he said.

While development tends to be harmful to snakes, there are some aspects of urbanisation, such as the year-round availability of water in pools or gardens, that may prove beneficial to “generalist” snake species that can live around people.