The effects of hypobaric hypoxia on behavior in the Pretest FST: (A) Females at 4.5K, 10K and 20K spent significantly more time immobile and those at 10K and 20K spent less time swimming than those at SL. (B) Males in all four groups were similar in their behavior in the pretest FST. (C) Immobility in the FST increased incrementally in females housed at altitude, and was significantly higher in all three high altitude groups vs. SL. (D) Latency to immobility dropped significantly in females housed at 10K and 20K, but did not change significantly in males. (Mean±SEM, #p<0.05, *p<0.001 vs. SL).