Tracking birds can be tricky — even with GPS technology. Around 70% of bird species are just too small to carry a GPS battery. But recently, Australian scientists developed GPS trackers that looked like little backpacks, weighed less than a gram, could charge wirelessly and could be quickly released with a magnet. When the researchers tested the trackers on Australian Magpies, though, the birds managed to pinpoint a tiny weak spot in the backpack and helped each other peck the trackers off. This showed evidence of altruism, a rare behavior among birds.

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