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Tree snakes


Cat-eyed tree snake of the genus Leptodiera                       (c) Andrew Gray

Tree snakes come in many colours and sizes, and most are highly nocturnal. In Costa Rica I come across many species, both venomous, like the beautiful Eyelash Viper, or non-venomous, such as the many active snakes that can be found living around aquatic breeding sites, where lizards sleep on their perches and night-time frogs are active.

At the moment I am teaching at La Selva Biological Research Station and during my time here have been supervising several student projects focusing on the morphological adaptations seen in different frogs and snakes. The cat-eyed snakes of the genus Leptodiera are species commonly known to eat lizards, frogs, and even the eggs of the many tree frogs in the main swamp here.


Yellow blunt-headed tree snake, Imantodes inornatus        (c) Andrew Gray

However, several other interesting species which fill a similar niche can also be found. Almost every night we have come across 1 or 2 species of Blunt-headed tree snake. Belonging to the genus Imantodes, these beautiful long snakes have huge eyes in comparison to their head size. Holding on with their long prehensile tails, these snakes silently manoeuvre their slender bodies between the slightest of twigs and branches.


Head of Sibon longifrenis, showing eye camouflage detail (c) Andrew Gray

Last night we found 2 other tree snakes belonging to separate but closely aligned genera that behave in exactly the same way – one was Sibon longifrenis. These snakes really are beautiful, and being various shades of green and brown they are extremely well-camouflaged amongst the moss. As other tree snakes, even their eyes perfectly match their cryptic colour.

We were lucky enough to find a pair in one tree, but rather than tree frogs, or frogs eggs, these snakes actually feed only on snails and slugs. Their mouthparts are specially adapted to extract snails from shells. To observe this behaviour in action is a very special moment for any herpetologist.


Costa Rican Course

IMG_8161aHere in Costa Rica I’m teaching on the field course with my highly knowledgable colleagues from the University of Manchester. Between us, and Alex Villegas, our Costa Rican bird specialist, we have almost all things covered. Apart from our students learning all about the flora and fauna, we too are learning lots from each other about our specialist subjects. We have a great team, and this year we also have great students, which is making the whole trip extremely enjoyable for all.

Whilst based at the Turrialtico we have been visiting local conservation initiatives, including night walks at the Costa Rican Amphibian Research Centre and today at CATIE, the largest agricultural college in Central America, where the students even got to chill out (literally at -15C) in the seed bank.


Neotropical weevil (c) Andrew Gray

Insects have dominated the first part of the course, with Dmitri our invertebrate specialist (Curator of Entomology at the Museum) and who is a world spider expert. We have had moth traps up at night and daytime searches for invertebrates of every shape, size and colour. He has taught us all so much already – and its been wonderful to have a glimpse into another zoological world!


The world of insects is an amazing one, and if you would like to find out more about Dmitri’s work and the wonderful invertebrate collection of Manchester Museum please visit his own great blog:

Entomology Manchester


The Annae and eye

Agalychnis annae eye

Yellow-eyed Leaf Frog, A. annae (c) Adam Bland

The Yellow-eyed Leaf Frog, Agalychnis annae, was described in 1963 due the yellow colour of its eye being recognised from specimens in the wild. Until then specimens of this species from Costa Rica were thought to belong to the species known as Agalychnis moreletii, another species occurring in Central America, because in alcohol preserved specimens (which lacked colour) looked exactly the same.

Eye coloration adds to the effectiveness of flash coloration used by Leaf frogs as a defence strategy and is also a defining taxonomic character of many species.


A. lemur (Night)


A. lemur (Day)

In some species, such as the Lemur Leaf Frog, Agalychnis Lemur, the eye colour can even change between day and night, adding to this frogs’ use of  cryptic coloration.

Splendid leaf frog eyes

The Splendid Leaf Frog, Cruziohyla calcarifer, actually has two colourations to its iris – yellow and grey. When sleeping this species has no nictating membrane to conceal bright coloration, so the centre, which is still visible, is the grey colour.

However, when it fully awakes the muscles around the eye expand and as the eye opens fully the yellow coloration now becomes visible, allowinging the striking bright eye coloration this species is known for. The same adaptation is is also shown in the sister species, Cruziohyla craspedopus. Find out more about these species’ eyes and read about Leaf frog eye coloration research by one of my past students here

Eye Rotation in Phyllomedusine tadpoles – Vol. 21; No.3

Finding A. annae (Yellow-eyed Leaf Frog)     

Elusive Ectophylla


Group of Tent-making Bats (Uroderma bilobatum) in Costa Rica (c) Andrew Gray

In Costa Rica there are several species of bat known as ‘Tent Bats’, bats known to modify their direct habitats in order to create resting sites. They form ‘tents’ from rainforest leaves, upon which they have nibbled to create the perfect place to protect them from harsh sunlight, predators, and rain during the day. I have come across many tents bats whilst in Costa Rica, such as Uroderma bilobatum, which use palm leaves to hide underneath (pictured above).

IMG_8126 2

Honduran White Tent Bats, Ectophylla alba (c) Andrew Gray

However, one species rarely encountered are the white tent bats of the species Ectophylla alba, a unique fruit eating species belonging to a monotypic genus. These elusive bats chew away the side veins extending out from large heliconia plant leaves causing them to fold down to form the ‘tent’.

IMG_8406 copy

Ectophylla alba (c) Andrew Gray

Unlike other tent bats, such as Uroderma bilobatum, these cling to the roof of the tent in very small colonies of only up to half a dozen individuals, consisting of one male and a harem of females. Until today, I have only come across them twice, once high in a plant which proved hard to get a view, and once close up in a mist net. However, to see these tiny beautiful bright yellow-eared bats again so close up was wonderful.

This time they were under a leaf  that was literally a metre from the ground, making it possible for me to observe them very closely without causing them any real disturbance – most tent-making bats take flight at even slight disturbances but these white bats will take flight only when the main stem of their tent is disturbed. This is possibly because they think they are so well camouflaged – and so they normally are, because as sunlight filters through the leaf it gives their white fur a greenish cast, almost completely concealing them from view.

Here is a short clip filmed today –  I hope you’ll enjoy seeing these bats too!

       Video of  Uroderma bats                Tara’s Tent Bat video              Shikaka    

Terrarium or Planetarium?

Dr Nathaniel Ward in 1829 created a device for transporting plants from the tropics back to the chilly shores of Western Europe. His container was called the Wardian Case and is the earliest known example of a terrarium. Since then technology has developed dramatically. Our understanding of plant culture; be it relative humidity, temperature, light levels etc. Our terrariums have subsequently changed to accommodate these requirements. During the 20th century Zoologists began to realise that these controlled environments duplicated the needs for tropical herpetofauna. Thanks to this, Manchester Museums ” Vivarium” could come into existence. But where does terrarium design go from here?

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Biorb Air with Intermediate/ Warm growing Orchid Species (c) T. Hughes

During my recent trip to the RHS Orchid Show I acquired a revolutionary new product called the Biorb Air. Although it may look reminiscent of a planetarium in miniature, it is actually at the forefront of terrarium design. With air purification, a 24 hour light cycle including a sunrise and sunset, a humidifier that automatically mists when humidity drops below 75%, the list goes on. I cannot emphasis how extraordinary this new terrarium is. My Biorb Air (photographed above) has many species of intermediate to warm growing orchids thriving within it. Some of which I have continuously failed to grow until now. I like to think Dr. Ward would have been amazed by how far his simple idea has come.

If your popping into the Museum this half term, why not appreciate the technology that goes into maintaining these rainforest displays, because without it there would be no animals and plants to enjoy.

London`s Temporary Rainforest                                  BiOrb Air

Altitude Addicts

Yesterday Brian Kubicki kindly joined us on a trip to look for high altitude toad and moss salamander species at about 2000 metres up Turrialba volcano. The conditions at that altitude resemble typical british weather, with cold temperatures, cloud cover, and rain. However, the flora and fauna to be found there are far from typical, with a wonderful array of specialised costa rican creatures and plants that can only survive there.


Tillandsia spp (c) Andrew Gray

High amongst the clouds, the trees are literally dripping with moss and epiphytes of every size and colour. Wonderful bright red bromeliads dominate the branches and air plants grow on the thinnest of twigs and cover the lichen draped bark of many of the trees. If you are interested in bromeliads, tillandsias, orchids, mosses and ferns then this is surely a plant science mecca.

Not so many biologist have covered the actual area we were in yesterday and there are still many species to be discovered there for sure. Some wonderful butterflies and other unusual insects were found, as well as a beautiful unusual bolitoglossa salamander living amongst the moss. Animals at this place appear to have little fear of humans, simply because many have never even seen a human.

Panterpe insignis

Fiery-throated Hummingbird, Panterpe insignis. (c) Andrew Gray

One example of this was when we came across a beautiful hummingbird that was happily resting on a low branch – it simply sat there watching as I was able to get within half a metre away, and still it looked completely chilled out. The air plants of the genus tillandsia are of growing interest for me and these mini bromeliads appear to have evolved to live almost anywhere in the rainforest. Being an epiphyte they need no soil to grow in and take all they need to grow from the humid air around them. Many of the colourful flowers they produce are simply stunning and clear rivals in the beauty stakes to the array of incredible looking orchids that occur at this altitude. I can certainly see why Brian finds high altitude species so addictive.


Back in Manchester, Tom has been planting out his own mini cloud forest in the shape of a new specially developed plant terrarium which provides conditions that would certainly suit many of these plants. Stay posted to read all about Tom’s super new plant terrarium, and in the mean time maybe check out Tara’s tillandsia tips for the ladies video below – air plants for air crew – I don’t think so! 🙂