Nest structures
Blue-capped cordon-bleus used flowers and their stems of Mollugo nudicaulis and grasses on the outside of the nest (Fig. 2a; Fig. 5a, c). As far as I checked the appearance of the active nest, I never observed that red-cheeked cordon-bleus used flowers and their stems on the outside of the nest (Fig. 5a, c–e). The domed nest seemed to be interlaced relatively looser in red-cheeked cordon-bleus than in blue-capped cordon-bleus (Fig. 2a, d; Fig. 5a, c–e), which was in accordance with past descriptions (Hockey et al. 2005, van Someren 1956). The inside was lined with fine grasses and several bird feathers (Fig. 2b, Fig. 5). Even when cordon-bleus used old weaver nests, they added fine grasses inside (Fig. 2b, Fig. 5c, Movie S1).