Why the female bird sings
Or sings so much less than her mate. Perhaps because the world is full of egg-eating predators? The research is interesting. But all it really shows is that predators are attracted to bird songs. Males singing at the nest presumably would attract them as much as females. Either singing away from the nest would serve as distraction. Without study of multiple species and how their habits vary with their nesting and chick-care practices, the conclusion seems poorly supported.