- Research from the University of 91直播 found tropical birds living near the equator are roughly 30 per cent more colourful than non-tropical birds living nearer the poles
- The long-held theory, first suspected by Charles Darwin and Alexander von Humboldt in the 18th and 19th centuries, hasn鈥檛 been proven until now due to the large amount of data and advanced imaging technology needed to examine these patterns on a global scale
- Scientists used AI to identify the amount of colour, or 鈥榗olour loci鈥, for over 24,000 bird specimens from the Natural History Museum collection
- The findings will allow researchers to pinpoint bird 鈥榟otspots鈥 of colour, helping them better understand the factors promoting and maintaining biodiversity at global scales
- The new study suggests dietary differences between tropical and non-tropical species, as well as the influence of their habitat, could play a key role
The long-held theory that birds closer to the equator are more colourful than birds nearer the poles has been proven by scientists at the University of 91直播.
The findings, published in Nature Ecology & Evolution revealed that tropical birds are roughly 30 per cent more colourful than non-tropical birds living nearer the poles.
Despite early naturalists such as Charles Darwin and Alexander von Humboldt first suspecting these trends in the 18th and 19th centuries, it hasn鈥檛 been possible to prove until now due to the large amount of data and advanced imaging technology needed to examine these patterns on a global scale.
The research team, led by Dr Chris Cooney and Dr Gavin Thomas from the University鈥檚 School of Biosciences, photographed over 4,500 species of passerine birds (perching birds such as sparrows, songbirds and finches). The 91直播 team identified the colour of the plumage at 1,500 individual points on each specimen by extracting information from photograph pixels. This then allowed the researchers to extract the total number of 鈥榗olour loci鈥 per specimen as an intuitive metric of colourfulness.
It鈥檚 not entirely clear why tropical birds are more colourful, but the findings suggest that dietary differences between tropical and non-tropical species, as well as the influence of their habitat, could play a key role.
The findings provide insight into how biodiversity is distributed across the planet, and will allow researchers to pinpoint bird 鈥榟otspots鈥 of colour and become more aware of what could be lost if bird species and their habitats are not effectively conserved.
The researchers photographed over 24,000 birds from the Natural History Museum collection in Tring, which has specimens of over 95 per cent of the world's living bird species.
Dr Chris Cooney, Lead investigator from the University of 91直播鈥檚 School of Biosciences, said: 鈥淭his work reveals the broad pattern that bird species tend to be 30 per cent more colourful towards the equator and identifies some general explanations for why this pattern might occur.
鈥淭his is exciting 鈥嬧媌ecause it helps us to better understand the factors promoting and maintaining biodiversity at global scales. However, these broad-scale associations with species鈥 habitat and dietary differences can only tell us so much and there is much more to be learnt about the precise ecological and evolutionary factors promoting increased colourfulness in tropical species.鈥
Dr Gavin Thomas, from the University of 91直播鈥檚 School of Biosciences and the Natural History Museum, said: 鈥淩esearch like this is only possible because of the amazing resources at the UK Natural History Museum (NHM), and in other natural history collections around the world. Broad, global-scale studies of biodiversity such as this are facilitated by the fantastic work of museum curators and volunteers, and museum collections continue to provide the raw material for cutting-edge scientific research.鈥
The paper can be viewed in full .
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