Maybe unmanned drone gliders without any cargo, just some sensors. Of course, if they're anything like the frigate birds themselves, one of these gliders will

Maybe unmanned drone gliders without any cargo, just some sensors. Of course, if they're anything like the frigate birds themselves, one of these gliders will eventually collide with a frigate bird. Then what? On second thought, just put sensors on some frigate birds and collect the data later, as this scientist is already doing. Sell the data to Google Earth. Split the profits with the birds.