Because the forest-dwelling thrush is notoriously elusive, it was, at first, difficult for scientists to learn whether there were in fact any physical differences between the two – as on the surface their plumage and anatomy are very similar. It wasn’t until several years of research, DNA analysis and painstaking comparison studies between the wild birds and specimens from 15 different museums that physical and genetic differences between the two were confirmed.
A Few Million Years of Separation
What scientists discovered from DNA analysis was that while the two different birds had come from the same ancestor, they had been breeding entirely separately for at least several million years. To put in it context, Professor Alström likened their genetic evolution and relationship to that of humans and chimpanzees.
The reasons for the split in breeding most likely occurred as an adaptation to surviving in their very different habitats – for example, the forest bird has shorter legs than the alpine bird, as longer legs are more of a physical benefit in open or mountainous habitats. Aside from the difference in leg length, the alpine species also has a longer tail.
Diverging the Species: One Becomes Three
Based on past research and comparisons, scientists agreed that the alpine species was the original Zoothera mollissima, while the “new” forest species became Zoothera salimalii. In another twist, however, during the course of fieldwork in China they discovered a third population of thrush in fact deserved reclassification from sub-species to its own species.
Of all the world’s unusual birds, one of the most fascinating is the beautifully coloured Hooded Pitohui, a songbird endemic to Papua New Guinea. As the world’s only scientifically confirmed poisonous bird, its vibrant plumage sends a warning to other animals to stay away – including humans.
A Dangerous Beauty
A member of the Oriolidae family of avians, the Hooded Pitohui (Pitohui dichrous) has striking orange and black feathers, a solid black head with a crest (which raises when on alert) and deep red eyes. It is medium in stature (growing to about 23cm) but has a powerful beak in relation to its size.
However, while undeniably attractive, the bird’s feathers (and skin) are coated with an alkaloid called batrachotoxin, which is one of the most potent poisons on the planet.
Batrachotoxin is the same neurotoxin found in the poison dart frogs, which secrete the poison from their skin and are, like the Hooded Pitohui, aposematic (endowed with a vivid colouration as a warning to potential predators).
A Deadly Diet
Batrachotoxin is also found in the Choresine Beetle (from the family Melyridae), which forms part of the staple food source of the Hooded Pitohui. Scientists believe these unusual birds eat the beetles as a chemical defence against lice and other ectoparasties. When the females lay their eggs the poison is transferred from their feathers to the outside of the eggs, which serves as a protection from snakes.
For keen wildlife watchers, well-organised professional bird tours provide the opportunity to travel to a host of exotic destinations around the world to experience sightings of rare and endemic avian species in their natural habitat. Anyone planning on joining one of the bird tours to Africa may be interested to learn of three newly documented species recently discovered in Ghana and the Republic of Congo.
Three New Species
An American research team working in Africa, headed by Dr Gary Voelker, confirmed the discovery in 2016 of three very similar birds that, while living in close proximity to each other, do not actually share any genetic similarities. Dr Voelker said the findings were particularly important and exciting because it was previously considered that Afrotropical forests were “static places where little evolutionary diversification has occurred.” The thinking that in this kind of environment birds that looked similar and existed in the same habitat were likely to be the same species is now under question, leaving the door open for potentially more new species to be discovered in the future.
Dr Voelker went even further, to say that the lack of documented diversity of avian species in the lowland forests of Africa is likely due more to a dearth of specimens than an actual absence of variation.