<b>Nestling retrieval behavior in two bunting hosts of the common cuckoo</b>

The experimental study was conducted in the Liuzhi area of Guizhou, southwestern China (26°10′-14′ N, 105°13′-24′ E). This area is characterized by a karst mountain landscape consisting of rivers, farmlands, villages and second forests (Zhang et al. 2023). From April to August in 2022 and 2024, we searched for bird nests in this area to carry out our experiments. In this study, two species of ground-nesting bunting hosts of the common cuckoo (Cuculus canorus) that breed sympatrically within the same area, namely the south rock bunting (Emberiza yunnanensis) and yellow-throated bunting (E. elegans), were studied. By placing their own nestlings next to the host nests and video recording the parental behavioral response, we aimed to explore the retrieval behavior of these two bunting hosts towards nestlings beside the nest. The results showed that neither species exhibited retrieval or rejection behavior towards the nestlings; the yellow-throated bunting ignored its own nestlings beside the nest in most cases, while the south rock bunting showed a moderate proportion of ignoring nestlings. Compared to the yellow-throated bunting, the south rock bunting had a higher feeding rate (43.75% vs. 15.38%) and a lower ignoring rate (56.25% vs. 84.62%) towards the nestlings beside the nest. Our study showed that no nestling retrieval behavior in two bunting hosts of the common cuckoo and the location of the nestlings may be an important factor affecting parental recognition. The hosts' behavior of not retrieving nestlings benefits the survival of parasitic chicks, which is advantageous for avian obligate brood parasites.