At high alititude, why the flying birds are not frozen, if the sorrounding temp is about 42 Deg Celcius.?

Answer 1

42 °C is a long way from freezing, dude.

It's cold up there, but birds aren't sitting still. The few species that can (and do) fly as high as you're implying (around 10,000m) are working out as they travel, what with the whole flapping thing. Combined with the insulation of feathers, and they birds are doing just fine.

Also note that a lot more species fly at 7000m than 10,000m, which is a huge temperature difference.

Answer 2

I think you might mean -42°C. 42°C is very hot.