They are very wary of people - if you stop nearby, they usually fly away very quickly. Some, like this one, get weak or sick and don't complete the journey.
I found this one lying flat on its belly, not moving, and it seemed it was dead. But this was a last show of strength. I took a few photos, and went to our work kitchen to find a bit of food for it. When I came back, I couldn't find it, but it was obvious from the look in its eyes and from the fact that it didn't try to fly away, that it was in bad shape. Most likely it would become a fox's meal in the night, if it would even last that long...