This ludicrous myth was spread via an email chain letter, notorious for misinformation & general silliness. The idea behind most of them is to see how many of your friends are gullible enough to forward them without checking to see if they are true, then having a good laugh.
Not only can birds see blue but some varieties of birds can see into the UV spectrum, allowing them to detect colors that humans cannot perceive.
Owls are nocturnal and have poorer color vision than their diurnal counterparts like harks or eagles.
The reason bluebirds, blue jays, blue herons, blue parrots & all sorts of other blue-plumaged birds attract mates with their blue feathers is because birds CAN see blue.