We often consider the air as simply a void – but it is in fact alive and vital. In a new study, researchers in Lund, the Netherlands and the USA introduce a framework for understanding the air as a habitat, just like a forest or ocean. The study highlights how environmental factors and interaction between species affect how animals are distributed in the aerial habitat.
“It 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,” explains Cecilia Nilsson, researcher in biology at Lund University.
The study discusses how slower insects prefer to fly closest to the ground, where the wind is moderate and temperature more equable. Bats’ favourite altitude is in the medium range, where they can hunt and feed on faster insects. At the highest altitudes, it is the birds that dominate, utilising thermals and tailwinds for efficient flight.
“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,” says Cecilia Nilsson.
In contrast to other habitats, the air is extremely volatile. Weather changes quickly, which affects access to food, energy consumption and competition between species. In the study, the researchers analysed both abiotic factors (e.g. weather and air pressure) and biotic factors (e.g. interactions between species) to understand why certain species fly high and others low – and why it can change from day to day.
“We want to encourage more studies that map which species use different altitudes, and under what conditions. It’s crucial for our understanding of how human impacts – such as wind power, drones or urban development – affect flying animals,” says Cecilia Nilsson.
These insights are not only of theoretical value, as they can have a direct bearing on nature conservation, urban planning and energy provision. Building tall structures often affects animals without us realising it.
“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,” concludes Cecilia Nilsson.
The study has been published in the research journal Trends in Ecology & Evolution: "Animal niches in the airspace".
