#sex characteristics

audible-smiles:

sex-limited polymorphism is most well known in males (think Calidris pugnaorUta stansburiana), but it also occurs in females. something like a quarter of all hummingbird species on earth have independently evolved an androchrome morph, which means that some females have the plumage and coloration associated with males. there are a lot of competing hypotheses as to why this happens. but last year a study on white-necked jacobins (Florisuga mellivora) a species where 20 to 30% of the females are androchromic, revealed that they faced less social harassment and were able to spend longer at feeders than females with typical plumage. the theory is that males of this species have such a reputation for aggression that if you look like one, the other males in the area will take more time sizing you up before trying to chase you away from a food source, and are more likely to go after individuals they perceive as easier targets (females) first. in the meantime, you get to eat more. a lot more work needs to be done to understand things like whether the androchromic females are themselves more aggressive, why only some females adopt this strategy, what genes are at play here, whether there is male sexual preference for one female morph over the other, etc. but it is SO COOL, and a good reminder that you may not be able to sex a sexually dimorphic species in the field as accurately as you think you can.