DuVal E.H. 1999 Journal 4 Las Alturas, Costa Rica 8 June H or 3 - 1/2 skull pneumatized. 1/3-2/3 complete Most of rear is typically complete, as well as part of front, extending back to the eyes. G or 4 - > 2/3 pneumatized, but < 95% complete A or 5 - Almost complete 95-99% Tiny dull pinkish area, or "windows" F or 6 - fully complete pneumatization U - unknown; examined skull, but unable to det. pneumatization. Different skull pneumatization pattern. Brood patch codes: N or 0 None present - breast more or less feathered. In Hummingbirds & young birds, breast is normally unfeathered S or 1 A loss of breast & some abdomen feathers, but most of the area is still rather smooth & dark red. V or 2 Vascularized - Abdominal skin thickened w/ ↑ fluid & vascularization This is the peak of incubation