The adult males are a strong black & blue while the adult females are brown. It is the immature males that have the mottled brown, blue & black look like this. See more photos in my Blue-black Grassquit Gallery. Including my favorite shot of females lined up on a barbwire fence at Carate adjacent Corcovado National Park back in 2009 on my first trip to Costa Rica. 🙂
¡Pura Vida!