I suspect a strong correlation between being able to take a photo of the dog and being near the dog.

> (I am a bit suspicious of that number seeing how the masters seem to always be nearby the dogs on the photos).

If they were far, it'd be hard to take their photo in a dense forest, no?

> Couldn't a low altitude drone be even more efficient ?

You'd need a dozen batteries to fly for a few hours, plus open areas to start/finish each flight, someone who knows how to operate one safely, etc.

It's from the adage: when a man walks one mile, his dog runs three miles around him and the tail traveled nine miles around them.

Border Collies can be easily taught to make broad sweeps left/right and circle back, so it's really the area around the trajectory of their master that gets covered.

You need the shortcoat type for this as our one would finish the day with all the seed stuck in his own fur.

Small drones have a pathetic battery runtime compared to a dog. Big drones aka planes are very expensive to run.