Nestling discrimination and feeding habits during brooding of Chestnut Thrushes

Abstract

Background Nestling discrimination and feeding habits during brooding are important factors affecting host selection of parasitic birds. Some host birds can avoid being parasitized by discriminating their nestlings or feeding food not suitable for parasitic nestlings. Thrushes are common medium-sized birds with widespread distribution and an open nesting habit, but they are rarely parasitized. It remains controversial whether this is due to feeding habits and/or nestling discrimination. Methods In this study, we tested the nestling discrimination ability and feeding habits of Chestnut Thrushes (Turdus rubrocanus) which is distributed in China’s multi-cuckoo parasitism system. Their nestling discriminability and feeding habits during brooding were studied by cross-fostering experiments and video recording to examine evolutionary restrictions on nestling discrimination and whether feeding habits are consistent with the growth of cuckoo nestlings. Results Our results indicate that Chestnut Thrushes using earthworms as the main brooding food can feed and maintain cuckoo nestlings and show no nestling discrimination. Conclusions The present study confirms that feeding habits cannot be regarded as the main factor affecting Chestnut Thrushes being rarely parasitized by cuckoos but suggests that egg rejection is likely to limit the evolution of nestling discrimination in thrushes.

Comparison of breeding strategies of two sympatric thrush species in an alpine environment

“…Although Chestnut Thrush is a common species, few people have published about its reproductive ecology before, and there are some reports about it in Lianhua Mountain, Gansu Province. Nest site characteristics and nest success (Zhao and Sun, 2018), egg rejection and recognition mechanisms (Yi et al, 2020b), nestling discrimination and feeding habits during brooding (Yi et al, 2020a), behavioral plasticity in relation to head volume (Zhao and Sun, 2016), and Parental attendance reduce nest predation during the incubation period (Hu et al, 2017), and brief field observations describing the breeding habits of the Chestnut Thrush in Wanglang Nature Reserve, Sichuan (Zhang et al, 1986), while more detailed studies on the breeding biology of the Chestnut Thrush are less available. There is little research on the reproductive habits of Kessler's Thrush, only Yang et al (2012) and Gao et al (2022) have reported on the reproductive habits of Kessler's Thrush, lacking detailed reproductive biology information (Yang et al, 2012;Gao et al, 2022).…”