Many of the bird’s nests you’ll spot this spring will have the familiar concave open shape, perfect for securing eggs and eventually chicks. About 30 percent of bird species are starchy in the bird kingdom, building elaborate domed nests with roofs. While ecologists have long believed that domed nests offer greater safety from predators and the weather, a new study suggests that songbirds that choose simpler nests may fare better in the long run.
Almost all songbirds can be traced back to Australia about 45 million years ago, when Australia was connected to Antarctica and covered in lush forests rather than dry deserts. Statistical analyzes of songbird traits and evolution found that dome nests were the “archaic architecture” of songbird homes. But the vaulted nests were then abandoned in favor of simpler cup designs when songbirds began spreading around the world about 40 million years ago.
Evolutionary biologists, such as Eliana Medina of the University of Melbourne, have wondered why so many modern birds abandon dome nests, and why only a third of birds build today. To answer that, she and her colleagues examined the environmental success of dome builders compared to cup builders, then correlated that data with their evolutionary history.
For more than 3,100 species of songbirds, Dr. Medina and his colleagues collected as much data as they could find: what the birds’ body size and ranges were, latitude and altitude, whether they lived in cities and, of course, what kind of nests they built. All this information was necessary because many factors influence how successful a species is, and Dr. Medina wanted to host a nest type as accurately as possible.
Her analyzes, published last month in the journal Ecology Letters, revealed surprising patterns. Songbirds that build dome nests tend to have smaller ranges, with more stringent climatic needs. Some ecologists believe that if domed nests provide better protection, it may allow bird ranges to expand and tolerate wider conditions. results of d. City contradicts this thinking.
Based on the findings, Dr. Medina suggests that dome builders may be less adaptable than cup builders. Although domed nests provide better protection from the elements, they also tend to be larger – easier for a predator to spot. Larger nests also take longer to build and require more materials, which limits when and where they can be built and makes birds less likely to leave a vulnerable habitat, such as the sunk cost fallacy with feathers.
“It’s probably really better to have a cheap, disposable nest that you can build several times a season,” said Jordan Price, an evolutionary biologist at Saint Mary’s College in Maryland, who was not involved in the study. “You are exposed to the elements, but you can escape from predators very quickly.”
The research has also shown that dome builders are less likely to live in cities, possibly due to a lack of suitable nesting sites, a scarcity of building materials or even because cities tend to be warmer. Dome builders also take longer to build nests, an axiomatic finding that has not yet been supported by a global analysis.
Then Dr. Medina looked back in time, modeling the natural history of nest-building traits and new species into the nearly 45-million-year history of songbirds. She found that dome builders had slightly higher extinction rates than cup builders, a result contrary to notions that domed nests were the safest.
“The cost-benefit analysis of building either an open cup nest or a dome nest has changed at some point,” said Dr. Price. “Some species kept their old ways, others created something new, which allowed them to really thrive.” However, the motivation behind the cost change is still unknown; Perhaps new parasites or predators have arrived, or climate change.
Today, dome builders face new challenges posed by humans, including changing climates, habitat loss, and built environments. Birds, like many other animals, are experiencing accelerated rates of extinction.
“There aren’t any real management actions we can do about a species’ nest,” said James Mouton, a postdoctoral fellow at the Smithsonian Migratory Bird Center, who was not involved in the study. “It’s not something we can train them in.” But conservation efforts can help restore and protect important dome habitats, supporting vulnerable populations.
“There are some very ancient lineages, and some birds that branched off the songbird tree very early,” Dr. Price said. “We need to find these species.”
“Some of these species that live on domes, it would be horrible to lose them,” he added.