Birds with the most extreme traits are at the highest risk of extinction. This has been reported by the British Environmental Association.
The Imperial College London study analyzed the extinction risk and physical characteristics (such as beak shape and wing length) of 99% of all living bird species, making this the most comprehensive study of its kind to date. The authors found that in simulated scenarios where all endangered bird species died, there would be significantly less physical (or morphological) diversity among birds than in scenarios where the extinction was random.
For example, among such vulnerable unique birds with a “pretentious” appearance there is a Christmas frigate (fregata andrewsi), which breeds only on Christmas Island, and Tahitian snipe (Numenius tahitiensis) migrate annually from their breeding grounds in Alaska to the islands of the South Pacific.
Ecologists suggest that highly specialized organisms with unusual features are less able to adapt to a changing environment and therefore have difficulty adapting to human influence and climate change.