The definition of the female is the sex with the larger gamete, not whether it is good at navigating. http://en.wikipedia.org/wiki/Female#Defining_characteristics

In the jacana, the males are the ones that are smaller and incubate the eggs (sitting on them to keep them warm), and the females are the bigger ones that go out and procure food, but the one that's called the female is the one that laid the egg. http://en.wikipedia.org/wiki/Jacana