Birds with extreme or uncommon combinations of traits face the highest risk of extinction, according to a new study published in the British Ecological Society journal “Functional Ecology”.
The study led by researchers at Imperial College London found that these unique birds are also the most threatened. “Losing these species and the unique roles they play in the environment, such as seed dispersal, pollination and predation, could have severe consequences to the functioning of ecosystems,” the researchers said.
Morphologically unique and threatened bird species include the Christmas Frigatebird (Fregata andrewsi), which nests only on Christmas Island, and the Bristle-thighed Curlew (Numenius tahitiensis), which migrates from its breeding grounds in Alaska to South Pacific islands every year.
Jarome Ali, a PhD candidate at Princeton University and lead author said: “Our study shows that extinctions will most likely prune a large proportion of unique species from the avian tree. Losing these unique species will mean a loss of the specialised roles that they play in ecosystems.
“If we do not take action to protect threatened species and avert extinctions, the functioning of ecosystems will be dramatically disrupted.”
The researchers looked at extinction risk and physical attributes such as beak shape and wing length of 99% of all living bird species. This is what makes it the most comprehensive study of its kind to date.
In the study, the authors used a dataset of measurements collected from living birds and museum specimens, totalling 9943 bird species. The measurements included physical traits like beak size and shape, and the length of wings, tails and legs.
The authors combined the morphological data with extinction risk, based on each species’ current threat status on the IUCN Red List. They then ran simulations on what would happen if the most threatened birds were to go extinct.
Although the dataset used in the study was able to show that the most unique birds were also classified as threatened on the Red List, it was unable to show what links uniqueness in birds to extinction risk.
Jarome Ali said: “One possibility is that highly specialised organisms are less able to adapt to a changing environment, in which case human impacts may directly threaten species with the most unusual ecological roles. More research is needed to delve deeper into the connection between unique traits and extinction risk.”