What birds get up at night? It was a simple question that amazed scientists for hundreds of years. There were wild theories that the birds went under the water, or sank into the mud. In the 19th century a German stork was found with an African spear through his neck, indicating that the birds were actually migrating. And in 1881 one scientist observed these migrating birds fly at night, pointing the telescope up at the moon.
Observing the moon for birds remained a significant niche science. It works like transit method in astronomy, in which exoplanets are measured when their silhouettes pass in front of the star. Ornithologist George Lowry began quantifying this in the 1950s, organizing mass campaigns to collect national data from these observations for the month. Between dusk and dawn, Lowry’s crew looked up at the full moon and noted the paths and directions of the flight, as well as the number of birds they saw. Because the technology at the time was relatively crude, they correlated the Moon’s dial with a round dial and indicated the “time” (meaning location) at which the bird entered and exited.
“We’re trying to automate this with our little robot,” said Wesley Hanikat, a researcher at the University of Oklahoma. “Because Lowry’s technique is useful but painful. I’ve looked at the moon so much over the last few years. “
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Honeycutt means LunAerowhich he and his team created at the University of Oklahoma. The hardware components LunAero includes a video camera, a small computer, a telescope and a motorized mount. It uses simple computer vision techniques keep the moon in focus and move with it. He can pick up birds that a passive observer can miss. A variety of telescopes can be placed on the mount if poultry farmers or ornithologists want to bring their own.
In addition to videos, the system also generates a log file with information about recording time, number of frames and camera sensor settings. The team is working on developing software that can analyze videos received from LunAero. But so far, after collecting the video, people have to manually extract footage containing the birds, and annotate their flight trajectories and patterns (e.g., slow or fast). Initial tests were conducted in April and May 2018 and 2019, at the peak of bird migration.
Researchers have already been able to obtain a large amount of information from the data they have so far. “It depends on the conditions and height of the birds. There are, of course, some birds you can identify [their] kind of maybe [their] species, if you make some assumptions about where you are and what birds you are likely to see, ”says Eli Bridge, an ornithologist and associate professor at the University of Oklahoma. “There are some birds with really distinctive flight patterns that you can choose from – we see night hawks flying up and down. In addition to simply counting them, you can get really accurate flight directions for them. You can visualize the wind drift. ”

The team’s goal is to use this technique in addition to other tools to track bird migration, such as radar aeroecology.
“Radar aeroecology is cool because you can see migrants and how they fly out of town or roosts, how they flow and altitude, but you can’t understand what you’re looking at,” Hanikat said. “You see there’s a water balloon [shaped mass of something] in this common part of the sky, but you can’t say what kind of bird it is, if it’s 12 birds, three insects in a cloak – we really don’t know until we look at it. ”
Anyone can build a LunAero unit from materials found in the workshop and engines on Amazon. Parts template and assembly instructions available to the public. The cost of LunAero components without a telescope is about $ 150. The most expensive component is the Raspberry Pi computer, which provides power to the system. “One of the benefits of having these really cheap tools is that you can deploy a lot of them all at once,” Hanikat says. “And if you have all these harmful sensors placed next to each other, you will eventually reach a critical mass of sensors where you will start producing data that matches high-end devices.”
After they published their technology in a 2020 article in a magazine HardwareXBridge and Honeycutt continue to upgrade their hardware, sending them on a try to bird lovers.
“Ideally, it would be a tool for civil science. I don’t know if we’re still there. There were a few ridiculous things that made it difficult, ”says Bridge. If there will be bad weather or the cloud will cover the moon, then it will be a long night of reconfiguring the device. Observations are related to the lunar cycle, and LunAero data can collect plumb lines if the Moon is less than half full.
“There were constant small adjustments, gradual improvements in how you keep the camera stable on different sights,” said Hanikat. “And while it’s not a big leap in equipment concept, it’s a trifle that grows the potential user base.”
The group is working on one of its first papers soon on social behavior that can be recorded and quantified using LunAero. “You can tell if the birds are flying alone, or in a group, or sometimes in a group, sometimes just a loose group,” Bridge says. “I don’t think there’s any other way to see it at night if you don’t have a searchlight, an infrared camera or another way to directly observe the birds.”
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Data analysis is a major barrier to the dissemination of widespread data documentation. “Analyzing data takes a little longer than collecting it, because you basically have to go through frame by frame,” says Bridge. “We don’t have the means to process a lot of video from a lot of people right now.”
And while it may seem that a tool like machine learning can help, unfortunately, this is not yet possible. “If you look at the video, many of these birds have one pixel,” Hanikat says. “Distinguishing one pixel that is a real bird from 10,000 pixels of a non-bird is a non-trivial problem that I don’t think machine learning techniques can handle yet. That’s why we’re making a more naive system that’s more computationally intensive. ”
Right now, the group is working on concept validation and initial paperwork for the tool. But five years from now, they believe it could be a unique addition to existing migration technology.
“If you have tracking devices enabled [birds], or if you see them on radar, you can’t directly observe the birds. The ability to directly observe birds, even when they fly over the moon, is a unique set of data, ”said Jeff Kelly, a professor of biology at the University of Oklahoma. “Integrating this data with tracking data will always be useful if you get information about where and when the bird arrived, but you can’t see it directly.”
There are still many mysteries when it comes to understanding why and how birds migrate. Do birds fly together, or separately, do they respond to the same wind conditions, or do they all fly at the same altitude? “It’s hard for us to understand exactly what these birds are dealing with,” Kelly says. “If we start talking about the infrastructure we build in the air, or bird collisions with buildings and light problems at night, such data, if people can specifically observe what is happening, will have a big impact on their ability to understand the problem. ».