Monday, 25 June 2012

Turacos Part 1

Great Blue Turaco
Living in woodland areas all over Africa from primary rainforest to wooded savannah are at least 23 species of more or lesss chicken-sized, usually brightly coloured, birds belonging to the family Musophagidae. Commonly called Turacos, some species are called Go-Away-Birds after their call, or Plantain Eaters. At Bristol we currently have three species, and the next few posts will cover each of them.

Saturday, 16 June 2012

Dinosaurs at Bristol Zoo

I should make a mention of the summer season exhibition we have at Bristol Zoo – a selection of life size animatronic dinosaurs and related events until the end of August.

As you enter there is a children’s activity tent where the smaller kids can play at excavating bones and identifying the bones of a thecodontosaurus (these are resin copies with built in magnets they can affix to a board). For the older kids there is a dinosaur lab with people from the Bristol Dinosaur Project (for their website, see ).

We have 10 different dinosaurs in total, plus a (partly assembled) Dimetrodon to show how the mechanics work. The models move, make noises, and in some cases scare small children, but so far it seems a great success. The species we have as you progress round the zoo are these:

Saturday, 9 June 2012

Conservation lecture: Ultraviolet vision in mammals

How good is his camouflage?
I have not posted for a while on the monthly conservation lectures we have at Bristol, but this week’s one was too interesting not to share. It was given by Professor Ron Douglas, who is Professor of Visual Science at City University, London, and was on the often misunderstood nature of colour vision and ultraviolet perception in mammals.

First, a brief outline of how colour vision works. Vertebrates have two types of light sensitive cells in the retina of the eye. Rod cells respond to more or less all frequencies of light, and when a photoreceptor cell is struck by a photon a chemical reaction occurs which generates a nerve impulse to the visual centres of the brain. Rod cells are more sensitive, and are used for vision in low light levels. However, they cannot respond differently to different frequencies, and so enable colour vision. This is carried out by the other cells, called cone cells, which occur in several varieties each containing a receptor pigment that only responds to a specific range of frequencies, from short wavelengths (= blue or UV light) through to long wavelengths (= red or infrared light). They are not tuned to a single wavelength, but have a peak absorption in different parts of the spectrum. The brain interprets the different strength of response from different cone cells to distinguish colours.

Monday, 4 June 2012

A Balkan invader

At around the same time the marshes of Britain were echoing to the bellows of fighting aurochs, a bird that would be an astronomically mega tick for a birder was nesting in fens across southern Britain from the Somerset levels to what would one day be called Norfolk. Today the Dalmatian Pelican Pelecanus crispus is found no closer to the UK than the Balkans, but from the Neolithic almost to Roman times it was a regular part of the British avifauna. How and why it ceased to be a British bird is something of a mystery, but the ecological requirements of the species today offers some clues.