On The Ground newsletter: Get a weekly dispatch from our international correspondentsGet a weekly dispatch from our international correspondentsGet a weekly international news dispatchEmail* SIGN UPI would like to be emailed about offers, events and updates from The Independent.... And knowing that might help us understand why many efforts to protect them have failed, and how we can do better in future.A small hopping engineering crewA single bettong weighs just a couple of kilos, but can move