Study maps how insects, bats, and birds fly at different heights

New Delhi, Oct 8 (PTI) A new study has mapped out the reasons behind different species' preferred flying altitudes -- slower insects prefer to fly closest to the ground, bats in medium range, and dominating birds at the highest.

Published in the journal "Trends in Ecology and Evolution", the study presents a framework where it treats air as a habitat -- similar to a forest or an ocean -- highlighting how the environment and interaction between species influence the distribution of animals in the atmosphere.

"(The framework) concerns not only where animals fly, but also why. Wind, temperature and air pressure are factors, as is the location of other animals. It's a dynamic environment that requires adaptation," author Cecilia Nilsson, researcher in biology at Sweden's Lund University, said.

Unlike other habitats, the air is extremely volatile, marked by quick weather changes that affect access to food, energy consumption and competition between species, the researchers noted.

To understand why certain species fly high and others low -- and why these patterns can vary daily -- they analysed both biotic factors such as species interaction and abiotic factors like weather and air pressure.

"We outline an ecological framework to advance understanding of how different properties of the airspace shape fundamental aerial habitat niches and how biotic interactions influence the realised niches," the authors wrote.

"Smaller animals, such as insects, operate at much lower Reynolds numbers (lower density of air) compared with birds and bats, meaning that they experience more viscous air," they said.

Slower insects were found to prefer flying closest to the ground, where the wind is moderate and temperature more equable.

Bats', on the other hand, favoured mid-level altitudes, where they can hunt and feed on faster insects, the researchers said.

At the highest altitudes, it is the birds that dominate, utilising thermals and tail winds to fly more efficiently, the study found.

"Then, of course, there are a lot of exceptions, such as insects, which in certain cases can be transported to high altitudes in thermals, and many birds that hardly ever venture up to higher altitudes but rather stay at the lower levels," Nilsson said.

"We hope that our framework will be a tool for both researchers and decision-makers. To preserve flying animals, we must understand that the air is an arena for ecological processes that is equally important as the land and ocean," the author said. PTI KRS KRS MG MG