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It's high, it's away from many, many predators - ideal for bar-headed geese. Steve Leonard spots four geese flying. He relates their progress: 'We're at 5,200 metres and they're battling into a headwind, at least a couple of hundred feet, 300, maybe more feet above us. This is maybe why Tenzing hasn't left. They can fly at 50 miles an hour, but this headwind must be making life so difficult for them - they're hardly making any progress… No, they're turning back, they're turning back. Maybe this is why they haven't left. God, and we thought life was tough for us, but flying into a headwind at this altitude, at this temperature... Just talking about it's knackering for me!' Being up here has really brought home what the geese are up against. It's not just the altitude - up here in the mountains there's some really extreme weather - they may have to contend with winds of 100 miles an hour or more. If they go for it and they hit the wrong winds they could be blown backwards, trapped on a mountaintop or knocked clean out of the sky. The timing has to be perfect.