Biologists identify traits that correlate with extinction of all bird species since 1500

University of Utah biologists have completed an analysis that identifies characteristics that correlate with all 216 bird extinctions since 1500, with the goal of informing conservation of endangered bird species.

Research published this month shows that the species most likely to go extinct faster are island-endemic species that lack the ability to fly, have large bodies with sharply angled wings, and occupy unique ecological niches. was. The study was published in the journal Avian Research.

While some of these findings reflect previous research on extinct birds, this is the first time that a bird’s characteristics have been correlated with the timing of extinction, said lead author and graduate student in the School of Biological Sciences. said one Kyle Kittelberger.

“I’m very interested in understanding extinction and lost species, and I’ve been trying to understand how we can use the past to better inform the present and future,” Kittelberger said. Ta. The bodies and wings of certain species of migratory birds have changed in response to climate change.

His team’s analysis of the ecological characteristics of more than 11,600 bird species around the world was compiled by University of Utah biology professor Chagan Šekercioğlu and the University of Utah’s Biodiversity and Conservation Ecology Laboratory. We used the dataset BirdBase. The research team examined a wide range of biogeographic, ecological, and life-history characteristics previously associated with extinction and extinction risk, not only for extinct birds but also for extinct birds with no recent confirmed sightings. were analyzed simultaneously.

“Importantly, we are looking at the biological correlates of bird extinction through the lens of when birds went extinct, so we can better understand why birds with certain traits went extinct when they went extinct. “We are providing a new element of extinction timing that is useful for understanding,” Kittelberger wrote in a series of posts about X.

By identifying the traits that make birds most susceptible to extinction, the findings could help guide conservation efforts for hundreds of species at risk.

“One of the strengths of the approach we use is that we can compare all of these traits to each other simultaneously, whereas many previous studies in the literature have only considered traits in isolation.”

Only about 2% of the world’s bird species have gone extinct since Kittelberger’s analysis began in 1500, but many more were already extinct by then. However, before 1500, there are no reliable records of extinct birds or data on their traits and characteristics.

This timing coincided with the rise of scientific observation, which led to the systematic recording of the ecology of plants and animals. It was also a time when European exploration was in full swing, and ecosystems around the world were being destroyed as a result of colonization and introduced species.

According to the IUCN Red List of Threatened Species, 1,314 bird species are currently at risk of extinction, or about 12% of the total.

Many species are so rare that they are functionally extinct, such as the akikiki (Olemystis bairdi), which is endemic to the Hawaiian island of Kauai. Kittelberger photographed the “Aki Kiki,” also known as the Kauai vine, at Alakai Nature Preserve in 2022. At the time, there were thought to be about 70 birds left in the wild. Today, only one remains.

Like many other bird species in Hawaii, the main threats to akikiki come in the form of invasive species, primarily malaria-carrying mosquitoes and livestock that destroy habitat, the Hawaii Department of Forestry and Wildlife said.

The single most important characteristic associated with extinction is insularity, i.e. species endemic to islands. Other traits that may increase extinction risk, such as body size, wing shape, and ecological specialization, are also associated with island insularity.

Pacific islands are home to a huge number of endemic species, many of which are currently on the IUCN list. No other archipelago has lost as much bird biodiversity as Hawaii, which has recorded 34 extinctions since 1500, according to the study.

The bird species that has experienced the most extinctions is the family Quinidae, which is a group of medium-sized, semi-amphibious birds that are distributed worldwide. The family lost 26 members, while the entire lineage of the Mohoidae, small nectar-sipping songbirds commonly known as Hawaiian honeyeaters, completely disappeared (the only one completely extinct in modern times). birds). The last member of this family, the Kauai’o (Moho braccatus), was last observed in 1987.

The discovery that surprised Kittelberger’s team was the correlation between wing shape and extinction. They found that bird species with higher wing index, more pointed wings, were likely to have disappeared earlier. Because pointed wings indicate stronger flight and dispersal abilities, the researchers predicted that such birds would be better able to respond to environmental pressures than those with rounded wings.

However, birds with rounder wings, i.e. birds with a smaller hand-wing ratio, proved to be more resilient.

“It probably has something to do with the fact that many of these extinct bird species were on islands. These species and their ancestors had to fly over wide open distances to reach these islands in the first place. “So many of these island birds have wings that are not necessarily longer, but more pointy,” Kittelberger said.

“Think of a bird like a swift or a swallow, or an albatross that flies over the ocean. Birds can’t fly very far, so their bodies are rounded, because they’re just moving within their local habitat patches.”

Ecologists, in contrast to generalists, face greater challenges when their particular ecological niche is altered, and therefore are less able to respond and adapt to disturbances such as invasive species or destruction of food sources. There is a tendency to

Among other findings, the study concluded that more than 87% of the species are endemic to the island. Almost two-thirds of the forest is inhabited by humans. 45% ate primarily insects and other invertebrates. and 20% are completely or partially unable to fly. Finally, large-bodied species were overrepresented on the extinction list.

“Heavier birds are more likely to be hunted, and there are several well-known examples of birds that have been hunted to extinction, in part for food, such as the dodo, the great auk (Pinguinus impennis), and the spectacled cormorant (Urile perspicillatus).” According to the study.

“Body weight is also related to island species, as island birds tend to be larger than mainland species.” Of the 43 species with average weights over 500 grams (1.1 pounds), a quarter 3 were endemic to the island.

The decade of the 1890s had the highest number of extinctions, with 21 recorded. The 1980s were once again the worst decade, with declines in 20 bird species, including the Kauai giant.

This latter decade is “remarkable because prior to and during this period, focused and targeted conservation efforts were already underway around the world,” the study says. “Although extinction rates have declined in subsequent decades, the number of globally threatened species has only increased.”