Egg recognition in Cinereous Tits (Parus cinereus): eggshell spots matter

Jianping Liu,Canchao Yang,Haitao Wang,Wei Liang,Jiangping Yu

doi:10.1186/s40657-019-0178-1

Jianping Liu, Canchao Yang + Show 3 more

Open Access

https://doi.org/10.1186/s40657-019-0178-1

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Abstract

BackgroundBrood parasitic birds such as cuckoos (Cuculus spp.) can reduce their host’s reproductive success. Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection against cuckoo parasitism. Studies have shown that Cinereous Tits (Parus cinereus) in China have a good ability for recognizing foreign eggs. However, it is unclear whether egg spots play a role in egg recognition. The aims of our study were to investigate the egg recognition ability of two Cinereous Tit populations in China and to explore the role of spots in egg recognition.MethodsTo test the effect of eggshell spots on egg recognition, pure white eggs of the White-rumped Munia (Lonchura striata) and eggs of White-rumped Munia painted with red brown spots were used to simulate experimental parasitism.ResultsEgg experiments showed that Cinereous Tits rejected 51.5% of pure white eggs of the White-rumped Munia, but only 14.3% of spotted eggs of the White-rumped Munia. There was a significant difference in egg recognition and rejection rate between the two egg types.ConclusionsWe conclude that eggshell spots on Cinereous Tit eggs had a signaling function and may be essential to tits for recognizing and rejecting parasitic eggs.

Highlights

Brood parasitic birds such as cuckoos (Cuculus spp.) can reduce their host’s reproductive success
When we speckled the eggs of White-rumped Munias, the rejection rate of speckled munia eggs by Cinereous Tits was significantly lower than that of the non-speckled ones, which suggests that eggshell spots play an important role in egg recognition for Cinereous Tits
Our results show that eggshell spots may play a key role in identifying and rejecting parasitic eggs for Cinereous Tits

Summary

Introduction

Brood parasitic birds such as cuckoos (Cuculus spp.) can reduce their host’s reproductive success Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection against cuckoo parasitism. Studies have shown that Cinereous Tits (Parus cinereus) in China have a good ability for recognizing foreign eggs. It is unclear whether egg spots play a role in egg recognition. The mutual adaptations and counter-defense strategies between brood parasitic birds such as cuckoos (Cuculus spp.) and their hosts are comparable to an arms race for studying coevolution (Rothstein 1990; Davies 2000, 2015). There are many explanations for the role of the egg spots (Kilner 2006; Reynolds et al 2009; Maurer et al 2011; Stokke et al 2017)

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