‘Adder-ing’ few more snakes to ZSL London Zoo’s Reptile House 

by ZSL on

In June, the herpetology team at ZSL London Zoo celebrated the arrival of eight Ethiopian mountain adders (Bitis parviocula), after a planned breeding two years in the making. 

It was the first time Ethiopian mountain adders, native to the highlands of east Africa and known from just a small handful of wild specimens, have been bred in a European zoo. The expectant mother-to-be received specialist attention from the keepers during her period of gravidity – a similar process to pregnancy. As the adult snakes were mixed together intermittently over a two-month period we aren’t sure exactly how long the gestation lasted, though it did fall between 125 and 190 days. Now we’re pleased to say the new arrivals have just passed their first health check with flying colours. 

These healthy young snakes are very small compared to the adults, measuring between 23 and 28cm long and weighing an average of just 18g they will likely be over one metre long and weigh more than one kilogram (about as much as a bag of sugar) when they reach adulthood. 

All eight snakes have started feeding and exploring their new homes – two great milestones in any young snake’s life.  

snake being weighed

Significance of their arrival

The parents of these young Ethiopian mountain adders arrived at the Reptile House as juveniles in 2016 so that the ZSL team could learn more about the needs of this amazing species – about which very little is known – and share knowledge about their care with zoos and conservationists around the world.  

First described by science in 1976, this species is believed to be endemic to the highlands of southwestern Ethiopia, between 1700 and 2800 metres above sea level. However, it is only known with certainty to reside in four locations in the country. With just four museum specimens available for study, important information regarding their conservation status and basic life history data are currently lacking. 

snake's head

How will this breeding success impact the species? 

Ethiopian mountain adders are so poorly known in the wild that they are yet to be assessed by the IUCN Red List, so at the moment we simply don’t know if they are widespread and common or rare and restricted to particular habitats. What we do know is the few specimens available to science have been collected in forest edge and grassland habitat. The human population of Ethiopia is estimated around 115 million people and, with strong reliance on land use in rural areas, the loss of native forest – wood is used for fuel or building material, and land is converted to agricultural and urban areas - is rampant. This increases the importance of learning what we can from the behaviour of animals in zoos.  

Vital knowledge gained from caring for the parents at London Zoo, accurately replicating their wild climate and seasonal requirements, can now be shared with others in the zoo community –  information that is essential for collaborative global conservation breeding programmes. Keepers are also working on several scientific studies to further learn and share important data. 

Working with conservationists and herpetologists to improve animal care and inform conservation fieldwork is a key part of international conservation charity ZSL’s work – as is educating the public. 

With fewer than 50 other Ethiopian mountain adders in zoos around the world, these young snakes are an important addition to the global zoo population. 

The youngsters and adults will live behind the scenes at London Zoo for a little while longer - getting the expert care they need – before some move to an enclosure where visitors can see and learn about them. The rest will move on to good zoos, so that the international zoo community can continue to inspire the public to care for wildlife and share knowledge about their needs and care. 


Book now and visit London Zoo's iconic reptile house

Quick facts 

  • Described by science in 1976 
  • We don’t really know a lot about them because so few museum specimens (4!) are known, and to date no field studies focussed on the wild habits of this species are known to exist 
  • Although likely quite widespread across the broadleaf forest habitat of southwest Ethiopia, we really do not know what the wild situation is for this species. It is likely that this species naturally inhabits forest clearing and edge habitats, and some specimens are found in recently-cleared land including coffee plantations, or at the edges of towns – one was even found in the grounds of a brewery! 
  • It is unknown, but they may be able to tolerate living in disturbed areas (like its relative, the puff adder) - however a large and relatively slow-moving venomous snake will likely not be tolerated by the local human population therefore loss of habitat (and the associated effects this brings) is currently likely the number one threat  
  • The photo below of the mother was ‘highly commended’ in the 2020 BIAZA photo awards: 

up close snake

Donate now to support more amazing conservation work

Select a blog

Careers at ZSL

Our people are our greatest asset and we realise our vision for a world where wildlife thrives through their ideas, skills and passion. An inspired, informed and empowered community of people work, study and volunteer together at ZSL.

Nature at the heart of global decision making

At ZSL, a key area of our work is the employment of Nature-based Solutions – an approach which both adapt to and mitigates the impacts of climate change. These Solutions, which include habitat protection and restoration, are low-cost yet high-impact, and provide multiple benefits to people and wildlife. We ensure that biodiversity recovery is at the heart of nature-based solutions. 

ZSL London Zoo

A blog for lovers of ZSL London Zoo, bringing you extraordinary animal facts and exclusive access to the world's oldest scientific zoo.

ZSL Whipsnade Zoo

Do you love wildlife? Discover more about our amazing animals at the UK's biggest zoo!


We're working around the world to conserve animals and their habitats, find out more about our latest achievements.


From the field to the lab, catch up with the scientists on the cutting edge of conservation biology at ZSL’s Institute of Zoology.


A day in Discovery and Learning at ZSL is never dull! The team tell us all about the exciting sessions for school children, as well as work further afield.

Artefact of the month

Every month, one of the pieces held in ZSL’s Library and at ZSL Whipsnade Zoo will feature here as Artefact of the Month.

Wild About

Read testimonials from our Members and extracts from ZSL's award winning members' magazine, Wild About.

Asia Conservation Programme

ZSL works across Asia, from the famous national parks of Nepal to marine protected areas in the Philippines. Read the latest updates on our conservation.

Remote Sensing in Ecology and Conservation

An Open Access journal for research at the interface of remote sensing, ecology and conservation.