The Streak-backed Oriole is a widespread oriole found from N Mexico south through Central America, although largely restricted to the Pacific Slope. It has bred on occasion in Arizona, and vagrants have made it well to the north, suggesting that there are some regular migratory movements in the northern populations at least. Perhaps the most unusual and intriguing aspect of this oriole’s biology is that in the north of the range the males are superbly bright, and the females reasonably dull. However as one proceeds southwards, the females become more and more male like until at the south end of the distribution the two sexes are nearly alike! Also male like females are more apt to help in territorial defense. The ecological difference appears to be that in the south they are year-round territorial, requiring a greater effort by the female to help in territorial matters than in the north where they are territorial only during the breeding season and also partly migratory. It is also interesting that monomorphic plumage in all orioles tends to occur when the female looks bright and male like, not as in many other birds where monomorphic species are both dull colored. The northern population of the Streak-backed Oriole has males which are very salmon to reddish orange on the head, at one point they were given the name Flame-headed Oriole. This very reddish coloration is not common in orioles, nor is the streaked back of this species; other orioles have either black backs or orange to yellow backs.