Birds That Make Nests With Domes May Perish


Most of the birdhouses you will see this spring will have the familiar open and hollow shape that is perfect for protecting the eggs and eventually the chicks. About 30 percent of bird species are star architects of the bird kingdom, building elaborate domed nests with roofs. While ecologists have long thought domed nests provide greater security from predators and weather, a new study suggests songbirds that prefer simpler nests may be better off in the long run.

Nearly all songbirds can be traced back to Australasia about 45 million years ago, when Australia was attached to Antarctica and covered with lush forests instead of parched deserts. Statistical analyzes of the characteristics and evolution of songbirds found domed nests were the “ancestral architecture” of songbirds’ homes. However, when songbirds began to spread to the rest of the world about 40 million years ago, domed nests were abandoned in favor of simpler cup designs.

Evolutionary biologists such as Iliana Medina of the University of Melbourne have wondered why domed nests have been abandoned by so many modern birds and why only a third of birds today build them. To answer this, he and his colleagues examined the ecological success of dome builders compared to cup builders, and then linked this data to their evolutionary history.

Dr. Medina and her colleagues collected as much data as they could find on more than 3,100 songbird species: how large the birds’ bodies and range, their latitudes and altitudes, whether they live in cities and, of course, what kind of nests they build. build. All this information was necessary because there are many factors that affect how successful a species is, and Dr. Medina wanted to determine the nest type as precisely as possible.

Analysis published last month Ecology Letters magazinerevealed surprising patterns. Songbirds that build domed nests tend to have smaller ranges with tighter climatic needs. If domed nests provide better protection, some ecologists have thought this may allow the birds to expand their range and withstand wider conditions. Dr. Medina’s results contradict this notion.

Based on the findings, Dr. Medina suggests that dome builders may be less adaptable than cup builders. Although domed burrows offer better weather protection, they tend to be larger – easier for a predator to spot. Larger nests also take more time to build and require more materials, potentially limiting both when and where they can be built, and making it less likely for birds to leave a dangerous habitat, such as a costly misconception with feathers.

st. “Maybe it’s actually better to have a disposable, inexpensive nest that you can build multiple times in a season,” said Jordan Price, an evolutionary biologist at Mary’s College of Maryland who was not involved in the study. “You’re exposed to the elements, but you can escape predators very quickly.”

The research also showed that dome builders are less likely to live in cities, perhaps due to the lack of suitable nesting sites, scarcity of building materials, or even because cities are warmer. Dome builders also take longer to build nests; this is an intuitive finding that has hitherto been unsupported by a global analysis.

Dr. Medina then looked back in time, modeling the natural history of nesting traits and new species through the nearly 45-million-year history of songbirds. He found that dome-builders had slightly higher extinction rates than cup-builders, contrary to notions that domed nests are the safest.

Dr. “The cost-benefit analysis of building an open cup nest or a dome nest changed at some point,” Price said. “Some species kept their old ways and some invented something new that really allowed them to thrive.” However, it is unknown what caused the cost change; new parasites or predators may have arrived, or climates may have changed.

Today, dome builders face new challenges posed by humans, including variable climates, habitat loss and built environments. Birds, like many other fauna, accelerating rates extinction.

“There’s no real management action we can take about a species’ nest,” said James Mouton, a postdoctoral researcher at the Smithsonian Migratory Bird Center who was not involved in the study. “It’s not something we can coach them.” But conservation efforts can help restore and protect important dome-nest habitats by supporting potentially vulnerable populations.

Dr. “There are some fairly ancient lineages, some birds that branched from the songbird tree very early,” Price said. “We need to be careful with these species.”

“It would be terrible to lose some of these dome-nesting species,” he added.



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