Why do birds with cup-shaped nests have a higher survival rate than birds with dome-shaped nests?

 Simply designed nests are more beneficial in the long run.

Most songbirds originated in Australasia about 45 million years ago. At that time, Australia was still attached to Antarctica and was covered with lush forests instead of arid deserts. Statistical analyzes of songbird characteristics and evolution show that dome-shaped nests are architectural styles from the time of their ancestors. However, this design was quickly replaced by a simple cup-shaped design when songbirds began to spread around the world about 40 million years ago.

A bird sucking purple nectar inside its dome nest.

Some evolutionary biologists, such as Iliana Medina of the University of Melbourne, wonder why dome nest designs are abandoned by most modern birds, and why do only a quarter of birds still keep this type of nest? To answer, her research team examined the ecological success scores of birds that chose to build ancestral versus modern cupping, then tied the findings to the evolutionary history of the birds. they.

For more than 3,100 songbird species, Dr. Medina and his colleagues collected as much data as possible: the birds' bodies and ranges, their latitude and altitude, and most importantly, the nest type. they build.

Her analyzes, published last month in the journal Ecology Letters, revealed surprising information. Birds that choose domed nests often have a small population range, more demanding climate needs.

Dr. Medina's results contradict some previous theories that if you build a dome nest, the species range will expand more quickly and withstand more weather conditions. From this, she concluded that dome-nesting species are less adaptive than cup-building species. While dome nests provide better protection from predators and the weather, they also tend to be larger - easier to spot by predators. Large nests also mean more time and material consumption, limiting when and where they can build, making it difficult for them to move away from these fortified homes.

Jordan Price, an evolutionary biologist at St. Mary's College of Maryland, who was not involved in the study, said: 'For living in the wild, it's better to have an inexpensive nest, the kind that you can build several times a season. You have many inconveniences, but in return, your chances of survival will increase if you face the enemy'.

A popular cup nest.

The study also shows that dome-builders are less likely to live in cities, perhaps because of a lack of suitable nesting sites, lack of materials and warmer city weather.

Dr. Medina then went back in time, modeling the natural history of many ancient songbird species as well as new species over the course of 45 million years. She found that the species that built dome nests had a slightly higher extinction rate than those that built the cup nests, a result that contradicts the hypothesis that dome nesting is safest.

Today, dome-building birds also face new challenges posed by humans, including climate change, habitat loss and construction projects. Birds, like many other animals, are going extinct at an accelerating rate.

James Mouton, a postdoctoral fellow at the Smithsonian Migratory Bird Center who was not involved in the study, said: 'We can't train them to quit the traditional nesting pattern but we can help restore them. and protect dome-nest habitat, in addition to strengthening potentially vulnerable populations'.