Island Birds Are Edging Towards Flightlessness

The new research reveals that island birds are becoming flightless. The study was performed in New Zealand-the idyllic haven for birds such as kakapo, flightless ducks, takahe, weka, iconic kiwi and a booming parrot with an owl-like countenance.

National Geographic reports that Natalie Wright from the University of Montana collected data from a total of 868 species. She found out that the flight muscles (the parts that people eat when you tuck into chicken breast) of the island birds are smaller compared to mainland relatives. Their legs are longer too.

"None of the species I looked at were flightless or close to being truly flightless," said Wright. "There's no point where, all of a sudden, they have much smaller flight muscles."

She began her study 20 years ago, when David Steadman, her undergraduate advisor, weighed the flight muscles of birds at the Florida Museum of Natural History. Wright observed then that the flight muscles of fruit doves on islands were smaller than that of the mainland. From then on, she examined more skeletons in five national history museums. She measured the size of the breastbone and the long bones in the lower legs for each one. The latter showed that it had heavy muscles.

Wright added that hummingbirds were reducing their flight muscles and developing longer legs on the islands without predators. This was just the same with flycatchers, honeyeaters, kingfishers, tanagers and also other groups that were really dependent on a flight. She also studied the Todiramphus kingfishers across the Pacific Islands. She said that they sat on perches and flew out to grab prey. Wright said that their foraging style requires flight, but they are becoming flightless.

The National Geographic Education states that the researchers also discovered that volant birds have stronger and much larger sternum, which is the bird's breastbone. It is thought of that a flying bird needs a stronger bone to support the weight of their muscles. They also found out that nearly flightless birds have less-developed flight muscles. There are two remarkable muscles of the island birds namely the pectoralis muscle, the part that draws the wings down and the supracoracoideus muscle that draws the wings up.