When Jessica Yorzinski chased large tail stones across a field, it was not at all to see who was pushing first. But she wanted the birds to crush.
Dr. Yorzinski had dressed the graves, which look a bit like crows but are in another family of birds, with head-to-head cameras pointing back at their faces. Like other birds, grackles press on all sides, splitting a semitransparent ball around the eye. Records showed that the birds spent less time squeezing in the most dangerous parts of flight. The result was published Wednesday in Biology Letters.
Dr. Yorzinski, a sensory ecologist at Texas A&M University, had been questioning how animals balance their need for pressure with their need for visual information about their environments.
People, she said, “often push, but when we do that we lose access to the world around us. It made me think about what might be happening in other species. ”
She worked with a company that builds surveillance equipment to make standard bird-sized heads. With bird’s eyes on the sides of his head, the ban held one video camera marked at the left eye and one on the right, making the bird look like a sports fan in a beer helmet . The headband was attached to a backpack with a battery and a dispenser.
Dr. Yorzinski grabbed 10 wild tail grackles, common in Texas, to wear this erection. She used only male birds, which are large enough to carry the equipment without trouble. Each bird wore a camera helmet and backpack while Dr. Yorzinski encouraged him to fly by running it over an outdoor park.
Afterwards, she broke down her flight videos into stages, from standing and going to landing again. She said she saw “clear patterns.” As the birds flew, their blinks were faster than when they were on the ground. And just before they landed, they were barely pushing.
“It makes a lot of sense to increase the visual input they receive at these critical levels of flying and landing,” she said. When they were flying fast, it could be catastrophic to hit something else. Choosing a place to sleep is also dangerous. Imagine a bird descending on a branch, Dr Yorzinski said: “If they were off a little, they might come ashore and fall to the ground.”
She also saw that the birds usually barked when they hit the ground. This may have been due to the need to squeeze after keeping their eyes open, or to protect their eyes from debris. Dr Yorzinski plans to carry out more experiments with birds navigating different environments, such as the location of a forest with more obstacles.
Graham Martin, professor emeritus of bird sensing science at the University of Birmingham in England, said the study was “an interesting work.” But he pointed out that the flights Dr. Yorzinski saw were only a few seconds long. He does not think there is still enough evidence to say anything widespread about how birds change their flight feathers.
“I think we need to see samples of audio behavior at longer flights and in other species before general decisions are possible,” he said.
Although she has only studied the issue in one bird species so far, Dr. Yorzinski’s results are similar to those in human pilots. A small study in 1996 showed that pilots in simulators pressed faster, and more often, while in flight, especially when landing. A 2002 study showed that pilots pushed less through the emergency parts of flight.
Human pilots are not just like birds, but Dr. Yorzinski said the parallels are interesting. During dangerous movements, grackles may benefit from keeping their eyes open. “I think it’s amazing that they can change the blink at this level at times when it’s so important for them to be aware of the environment around them,” she said.