'This is an interesting evolutionary puzzle.'

Standing out from the crowd isn’t always a good thing. 

Birds with uncommon traits like big beaks, long tails, and extended wings are more likely to be threatened and face extinction, new research finds.1

Losing these birds with rare physical features could seriously impact the ecosystem because of the key roles they play in the environment.

“We are fascinated by the diversity of the planet’s bird species, from tiny hummingbirds to majestic albatrosses. At the same time, we are deeply concerned about the threats these birds face,” lead author Jarome Ali, a Ph.D. candidate at Princeton University, tells Treehugger. Ali completed the research at Imperial College London.

“We wanted to use a data-driven approach to better understand what the consequences of extinction could be, in terms of how it will affect bird diversity.”

For their work, researchers analyzed measurement data collected from 9,943 bird species, which is about 99% of all living bird species. The information came from both living birds as well as museum specimens. The measurements included beak size and shape, as well as the length of legs, tails, and wings.1

“This massive dataset allowed us to understand the global trends,” Ali says. “As a global community, we are collectively responsible for the stewardship of the environment and our research makes it clear that the problem of extinction is one for the entire planet. Of course, the specifics may differ at local scales, and this is where future research will be crucial.”

Researchers combined the information on physical traits with the birds’ risk of extinction. They consider each species’ status on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Next, they ran simulations about what would occur if the most threatened birds on the list were to become extinct.1

“All our simulations showed that extinction has worse effects on the diversity of bird shapes than we expected. This is deeply concerning, but not shocking given that we first found that threatened birds were more unique than non-threatened birds,” Ali says.

“We found it very interesting that, in general, larger birds were also more unique in shape. Think about all the small songbirds, they have very similar shapes. Now compare that to the difference in shape between an ostrich and an eagle. There is something about large size that is related to unique shapes. This is an interesting evolutionary puzzle.”

The results were published in the journal Functional Ecology.

Impact on the Ecosystem

Agami heron (vulnerable).

Joe Tobias

Researchers aren’t sure what explains the link between unusual birds and their extinction risk.2

“Unique birds are likely to play specialized roles in the ecosystem. One possible explanation is that as habitats come under threat, these specialized roles are likely to be the first to be targeted,” Ali says. “For example, if you are a hummingbird and specialized to feed on a small subset of plants, then damage to your habitat will be worse than if you were a less unique, generalist bird that eats a whole range of foods.”

The loss of these rare birds could have an impact on the environment because their specialized role in the ecosystem is lost.2

“We lose specialized pollination, scavenging, predation, seed dispersal and so much more—these are integral to ecosystems,” Ali says. “Just imagine an ecosystem where the pollinators are gone. Important links in the food web would be in great danger and the whole system would no longer function properly.”

The findings are key because they provide additional evidence that protecting threatened species is important.

Ali says, “Our findings imply that we cannot simply hope that a non-threatened species will come in and fill the role of a threatened species.”

Fact checked by Haley Mast