July 17, 2024

Starlings in the Wind Tunnel: Always Follow the Leading Bird |  Sciences

Starlings in the Wind Tunnel: Always Follow the Leading Bird | Sciences

Flying in a flock behind a leader bird not only provides protection from birds of prey but also saves energy. At least this is what experiments conducted by an American research group on starlings in a wind tunnel indicate.

“Many bird species gather in flocks for reasons ranging from predator defense to navigation,” the team wrote in the journal Proceedings of the National Academy of Sciences (“PNAS”). Data suggest that certain types of flocks—specifically in V formations or relay formations for larger birds—provide the advantage because they reduce energy costs. However, the typical flock flights of young birds can increase this effort. It has not yet been verified how much energy animals actually use on group treks, writes the group led by Tyson Hedrick and Sonya Freeman of the University of North Carolina at Chapel Hill.

So, she placed individual starlings (Sturnus vulgaris) and two or three animals in a wind tunnel equipped with cameras. On the one hand, the researchers observed how the birds changed their flight position in the wind tunnel. On the other hand, they determined metabolic costs by measuring carbon dioxide emissions in the air they breathe.

The greatest at the top

Scientists have observed that starlings often change their relative position in groups of three, but on average they fly in a V formation in experiments. Most of the time, the two trailing animals were located 1 wing behind and 0.8 wings to the side of the leader bird.

The flight cost those birds flying behind the leader much less energy than if they were flying alone in the wind tunnel—this effort was up to 25 percent less, depending on the location. It is said that the savings may be linked to the eddies created by the leader bird.

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Some previous studies on birds in the wild using computer models also indicated lower energy costs in formation flight, the researchers wrote. However, they did not focus on the actual energy consumption.