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The spotted green pigeon, a mysterious species collected in the 1700s, turns out to have been a flying relative of the dodo that likely lived in the trees of the South Pacific.


Only two specimens of the pigeon were ever described, in 1783, and since then one has gone missing. The location they were collected from was not recorded, but they are associated with South Pacific voyages. The only remaining specimen is held at the World Museum (formerly Liverpool Museum), National Museums Liverpool.


Quest for identity


In its original description, the spotted green pigeon was said to closely resemble the Nicobar pigeon, a bird native to Indonesia that prefers to live on small remote islands. This, and it's obscurity, led some to speculate that the spotted green pigeon was just an unusual variety of the Nicobar pigeon.


Determined to find out once and for all, the World Museum asked our bird expert Hein van Grouw and colleagues in Australia to investigate their specimen. Using detailed morphological analysis and genetic testing, the team identified the spotted green pigeon as a distinctive species in its own right.



The only remaining specimen of the spotted green pigeon.

Photo by Hein van Grouw.


Dodo connections


Preliminary results from the genetic testing reveal the pigeon is in the same family as the dodo and its extinct flightless relative the Rodrigues Solitaire. It's somewhat of a mystery how the specialised flightless dodo got to its isolated island habitat, but finding more relatives can help clarify the picture. The addition of the spotted green pigeon to the lineage may add some evidence to the 'stepping stone hypothesis', which suggests ancestors of the family island-hopped from India or Southeast Asia.


van Grouw is completing his morphological analysis that will help determine what kind of lifestyle the spotted green pigeon had. It was originally described as having short wings, suggesting a ground-dwelling lifestyle like the dodo, but this turns out not to be the case, and it is more likely that it lived in the trees eating fruit and berries.


Gone already


Determining the spotted green pigeon as a separate species has another consequence. Since no others have ever been seen, it can confidently be added to the extinct species list.


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Sub-millimetre-sized wasp discovered in scientist's son's playground.


Museum wasp expert Dr Andrew Polaszek has identified a new species of tiny wasp living inside whiteflies on a tree in his son's playground in Sevenoaks, Kent.


The wasp is a parasitoid. While true parasites depend on other organisms their whole lives, parasitoids just lay their eggs in other organisms. The larvae of newly discovered wasp, named Encarsia harrisoni, are born inside whiteflies and eat their way out.


It was the whiteflies on a maple tree in the playground that alerted Dr Polaszek to the presence of the wasp:


'I noticed some of the whiteflies looked slightly different to the others so I took them to the laboratory. When I saw the wasp inside I knew it looked different to anything I'd seen before.'




Not a tourist


Dr Polaszek made the discovery five years ago, but there was a lot of work to do to define it as a new species. Even more surprising to Dr Polaszek is that the new species is native to the UK.


'I thought it might be a species from Northern Europe that had come over to the UK. I was really surprised when I realised it was native to the UK and was previously unknown. Finding an undiscovered insect in the rainforests of Borneo is relatively easy but the fauna of England is some of the most studied in the world so to find something new here is a real thrill, and makes it even closer to my heart.'


In those five years Dr Polaszek has been regularly collecting the new wasp, but has never found a male, suggesting that females can lay eggs without them. This is similar to other parasitoid wasps, such as the related Encarsia formosa.


What's in a name


The new species is named after local scientist Dr David Harrison, chairman of the Harrison Institute that promotes taxonomic research to support biodiversity studies and conservation. The institute is only a few hundred yards from the trees where Encarsia harrisoni was discovered.


Dr Harrison has a few species named after him, but finds the new wasp especially intriguing:


'I now have a flea, a bug, a sand cat and a wasp named after me, which is obviously quite an honour. Dr Polaszek's wasp is a particularly interesting one - it was found right here in Sevenoaks just a few hundred yards from my home.'


Fossil foragers

Posted by Hayley Dunning Jul 15, 2014

Researchers discover evidence of optimal foraging strategies, which are found across the animal kingdom today, in 50-million-year-old sea creatures.


How do you find food in a wide landscape? Foraging for scarce resources requires an optimal walking strategy: you have to cover lots of ground without going back over your trail or getting disoriented by obstacles.


The optimal strategy is a mathematical pattern called a Lévy walk, and researchers - including Museum palaeontologist Prof Richard Twitchett - have just discovered that it appeared at least 50 million years ago in ancient sea urchins.


Walking to the same beat


A Lévy walk consists of lots of shorter steps, indicating an intense hunt for food in one area, interspersed with a few longer steps, as the animal travels between searching areas. It's observed today in everything from sharks and insects to modern human hunter-gatherer tribes.


By analysing trace fossils - the trails imprinted in rocks by creatures walking over the sea bed - Prof Twitchett and colleagues were able to find the first evidence of Lévy walks in extinct animals. They think the foraging strategy of a Lévy walk may have arisen as a response to decreased food availability after past climate change and mass extinctions.



A: Trace fossil trail of an ancient urchin. B: Digitised version of the trail, showing a Lévy walk pattern.


Window on the past


Prof Twitchett said:

'It's amazing to think that 50 million year old fossil burrows and trails have provided us with the first evidence of foraging strategies in animals that live on and in the deep-sea floor - studies which would be nearly impossible and very expensive to do in modern oceans. Trace fossils are remarkable and beautiful records of the movements of ancient animals which have been frozen in time and tell us so much about the evolution of life on Earth and the environments of the past.'



Egg arms race

Posted by Hayley Dunning Jul 8, 2014

Birds targeted by cuckoos develop sophisticated egg patterns to help them recognise the fakes.


Cuckoos infamously lay their eggs in the nests of other birds, forcing them to care for their young. But species that are repeatedly targeted by cuckoos have developed a range of complex egg patterns to help distinguish the invader's eggs and kick them out of the nest.


Cuckoos will hatch before their nest-mates and throw them out, so that the parent birds will only raise the cuckoo. When a host bird recognises a cuckoo egg, they may puncture it or throw it out the nest before it hatches.


Signature patterns


Scientists from Harvard and Cambridge Universities developed a pattern-recognition software called NaturePatternMatch that mimics the way birds see the world. Using the extensive egg collections of the Natural History Museum at Tring, they then analysed the eggs of eight bird species commonly targeted by cuckoos.


They found that where cuckoos had developed accurate copies of host-bird eggs, the host birds had in turn developed more complex egg patterns. 'The egg patterns on cuckoo and host eggs reveal an evolutionary arms race,' said lead author Dr Mary Caswell Stoddard from Harvard University.



Samples of cuckoo's eggs in host bird clutches from the Museum's collections. Cuckoo's eggs are often bigger than their host's.


'In many cases, cuckoos have evolved excellent egg mimicry in order to trick host birds into accepting foreign eggs. In these instances, host birds have evolved excellent egg pattern signatures on their own eggs as a defence.'


The host birds studied used different techniques to set their eggs apart. Some females of the same species, such as the great reed warbler, laid very different eggs to each other, but very similar eggs within their own nest. Others, such as the brambling, lay eggs with unevenly spaced, sparse markings, making a good signature.


Collections and tools


Museum egg and nest curator Douglas Russell said he was 'fascinated by the insights [this paper] provides into the particular mechanisms that appear to be involved.' The extensive bird collections, which cover 95% of all bird species alive today, are involved in numerous studies.


'They can contribute to research as diverse as understanding migratory routes and investigating chemical contamination of the environment over time.'


The NaturePatternMatch software may also be used in a range of projects. 'How do animals recognize their neighbours, enemies and kin? How have visual signals evolved to maximize distinctiveness? Computer vision tools like NaturePatternMatch will help us answer these important evolutionary questions,' said Dr Stoddard.