Chickens in captivity

Hi again. Hopefully now you know more about the amazing mountain chicken and the reasons why it is so threatened. Now to tell you some of the main things we have been doing to help save it from extinction. As you read last time there is no cure yet known for chytrid so one of the first things we had to do was rescue mountain chickens from the wild on Montserrat. In 2009, when chytrid was discovered on Montserrat an emergency rescue mission was undertaken which took 50 frogs to Jersey and was so important it made the news across the UK: http://www.theguardian.com/environment/2009/apr/21/wildlife-conservation

Mountain chickens being rescued from Montserrat (Photo: G. Garcia/Durrell)

The frogs were flown over to the UK and then Jersey packed in boxes. In Jersey Durrell started to breed them and sent some of the frogs to other zoos in London, Chester and Sweden. When keeping the frogs in captivity they have to be kept in ‘bio-secure’ conditions. This effectively means they are in quarantine and is designed to prevent any diseases getting into the frogs. When keepers go into these areas they have to change footwear, wear suits, masks and gloves to ensure they don’t bring anything in!

Looking after these frogs in captivity is not straightforward as they are very big and eat a lot so cost a lot of money. But keeping a captive breeding population is very important to ensure their survival, especially when they disease is still present in the wild. Also, Keeping them in captivity also allows us to find out things about them that would be very difficult to do in the wild such as how they breed. Knowing as much about the species as possible is very important for making decisions on how to protect them in the wild.

Follow this link to see a video and article on the alien like tadpole behaviour of the mountain chicken, first recorded at Jersey: http://news.bbc.co.uk/1/hi/8185125.stm

As well as having breeding populations overseas there is also a captive breeding centre on Dominica itself. This was set up in 2010 and is the first amphibian breeding centre in the country. This is very important as it will allow people living in Dominica to learn how to look after and breed mountain chickens in captivity with the ultimate aim to release them back into the wild.   

Mountain chickens in the Dominican captive breeding facility (Photo: S-L. Adams)

Next blog I'll tell you about some of the research

What has caused the mountain chickens to almost disappear?

In my last blog I told you that the mountain chicken is listed as Critically Endangered, which means it is facing the threat of going extinct very soon unless something is done. But why is this amazing frog so close to going the way of the dodo?

To understand the whole story we must first go back in time. Hundreds of years ago before Christopher Columbus discovered the Americas and Europeans began to arrive, the mountain chicken was found on 7 different islands in the Caribbean instead of the 2 it is today. As Europeans arrived and settled on the various islands of the Caribbean they brought with them, either deliberately or unintentionally, species that did not exist there before. These included rats, cats and small Indian mongoose.

Red islands where the mountain chicken is still found. Blue Islands where it is now extinct

Mongooses will eat pretty much anything, including frogs and is a successful predator. The native animals would never have seen a mongoose (or a cat or rat) so would not know how to react. On all the islands where mongooses were introduced the mountain chicken went extinct suggesting it was a main reason. Only Montserrat and Dominica have never had mongoose and it is no coincidence that they are the only two islands on which the mountain chicken still survives.

Small Indian mongoose - probably the main reason why the mountain chicken went extinct on the five other islands

So why if there are no mongooses on these two islands have the numbers of mountain chickens dropped by over 90% in the last 15 years? Local people did hunt the mountain chicken for food but not in the numbers to cause such a huge drop so quickly. Was it loss of habitat? Not really as they were quite happy in gardens on these islands although a volcano on Montserrat erupting did not help! No the answer is disease. In this case a particularly nasty, amphibian killing disease called chytridiomycosis or chytrid (pronounced ki-trid) for short.

Healthy mountain chicken (Photo: S-L Adams)

Chytrid isn’t caused by a virus or bacteria but by a fungus that infects the skin of amphibians. Unlike reptiles, amphibians have permeable skin, which they use to help absorb gases and water many species use their skin to help them breathe. When the fungus infects the skin it can inhibit these processes causing many problems for the animal and eventually death. Some of the visual signs of chytrid in mountain chickens are animals looking lethargic (tired), reddening of the belly and legs and skin peeling off.

Mountain chicken infected with chytrid (Photo: S-L Adams)

One strange thing is that chytrid is not deadly to all amphibians. Some species can carry the fungus but appear to be completely uninfected by it. For other species however, like the mountain chicken, it is deadly and it has been the main reason for a number of amphibian species going extinct in Latin America and Australia. Why there is this difference between species is one of the many questions scientists are trying to answer.    

The other big question scientists are trying to answer is how to cure chytrid and to stop it from spreading. At the moment there is no known cure or treatment and is one of the things this project is trying to help with. Find out more in my next blog!

Introducing the Mountain Chicken

Hello my name is Jeff and I work for Durrell as their Amphibian Programme Officer. I am based in the City of Bath and my job means I am responsible for developing and looking after all of Durrell’s amphibian projects around the world.

Me on a raft (Photo: Jeff Dawson)

I have been working at Durrell since July last year before which I have lived and worked in a number of countries around the world including Madagascar, Papua New Guinea and Montserrat. By coincidence, one of my projects with Durrell and the species I am going to tell you about is from Montserrat - the mountain chicken!

Now I know with that name it sounds like a bird but it is in fact a frog … but not just any frog, it is the second largest frog in the world. Females are larger than males and can reach lengths of over 20cm and weigh over 700g! Much bigger than the frogs you or I would find in our garden ponds. They have very powerful hind legs and can jump over 2m in a single leap ... that's the height of a tall man! It is due to these meaty hind legs that it got its name mountain chicken as they were a popular food dish with local people that apparently tasted a bit like chicken.

Mountain chicken, Montserrat (Photo: Jeff Dawson)

The mountain chicken is only found on two islands in the Eastern Caribbean - Montserrat and Dominica. It used to be widespread over both islands, commonly occurring in peoples back gardens but is now only found around streams in forest or other dense vegetation. It is nocturnal, meaning it is active at night and spends the daytime resting in holes or rock crevices.

Like all amphibians the mountain chicken is carnivorous and a pretty unfussy eater, eating anything it can fit in its mouth. This includes insects, snails, tarantulas and even small lizards and snakes. It is a sit-and-wait or ambush predator. This means it does not chase down its food rather it uses its colouration as excellent camouflage to wait motionless until dinner comes walking or crawling past. As both Montserrat and Dominica have no native land mammals the mountain chicken is a top land predator on both islands and therefore a very important part of the food web.

Tarantula for tea! (Photo: SL Adams/Durrell)

Unlike frogs we have in Britain the mountain chicken does not lay eggs in water. Instead the female makes a foam nest in a burrow in which the tadpoles develop. Both the female and male take turns guarding the nest from predators. The female only produces one fertile nest a year of between 25 and 60 froglets which is very low reproductive rate for a frog. This is more similar to birds than other frogs so the mountain chicken is really a bit more like a bird like than just its name!

Mother guarding her tadpoles in nest (Photo: G Garcia)

However, the mountain chicken is also one of the rarest frogs in the world with perhaps less than 100 left in the wild. It is listed as Critically Endangered which means that it is very close to going extinct, just like the dodo and dinosaurs, unless conservationists like myself can find a way to save it. There are a number of threats facing it but the main one is a lethal fungal disease that is commonly called chytrid. This is a fungus that infects the skin of amphibians and can cause mass die offs in species, like the mountain chicken. I’ll tell you more about this and why our work on it is so important in my next blog.