Hawk Cam Shows What Raptors See When Hunting

A tiny video camera mounted to the head of a Northern goshawk named Shinta shows what birds of prey see when hunting, and reveals a surprising connection with humans.

When people as well as raptors want to find something, they do not just hold their head in one position and rivet their eyes to a single spot, even if they hone in on their target. Instead, the new research published in The Auk: Ornithological Advances shows that hunters and other searchers randomly change their head movements and direction of gaze.

It is a very animalistic behavior that we are not even really aware of in the moment, unless we make a conscious point of noting every one of our head turns and eye movements, which is near impossible.

"Researchers have hypothesized this visual search behavior arose deep in evolutionary time from the need for predators and prey to prevent each other from knowing where they would look next," senior author Suzanne Amador Kane of Haverford College told Seeker. "This has been compared to the hero and villain in an old movie dodging back and forth about a table, each trying to surprise the other."

To investigate the behavior, Amador Kane and her team studied the timing of head turns by birds of prey such as hawks, eagles and falcons as they searched for food in the wild. They used two sources of data: videos of wild birds filmed in the field, and video filmed by Shinta, who was wearing the mini video camera fitted into a small helmet.

Shinta's videos provided by falconer Robert Musters are below:

The scientists found that Shinta as well as the other birds alternated periods of rapid head or eye movements, called saccades, with periods where their vision was fixed on a specific point. Such movements are based on environmental information, such as rustling trees and available light. The time between saccades changes as a bird detects a potential target, like a rabbit or pheasant.

Falconer Robert Musters designed the tiny camera-holding helmet worn by Shinta, and is the man seen from her viewpoint in the videos.

Amador Kane said that, in order for us to better understand the process, we imagine a hunting bird making a decision to change its direction of gaze based on the visual info streaming in as it visually scans its environment.

"The longer it looks and finds no indication that prey is present, the less likely it will find prey initially and the more likely it is that looking in a different direction will be more profitable," she said. "However, if the predator gives up after a predictable time, the prey can use that regular timing in its own decisions about when to flee or break cover based on that information."

What actually happens then is "a compromise between these two factors, and is indeed similar to that found for human visual searches."

Graham Martin is a University of Birmingham professor and expert in raptor hunting behavior. He was not involved with the study.

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