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Two Bunting Species Rejected 92–100% of White Foreign Eggs but Only 40–45% With Host-like Patterns

Godlewski's bunting standing on rocky ground
Research · Behaviour

Two closely related bunting species that can serve as hosts of the common cuckoo (Cuculus canorus) rejected foreign eggs much more often when the markings differed strongly from their own. The experiment in China tested Godlewski’s bunting (Emberiza godlewskii) and yellow-throated bunting (Emberiza elegans). In both species, rejection increased stepwise as the experimental eggs became less similar to their own eggs.

The researchers used budgerigar (Melopsittacus undulatus) eggs as foreign eggs and gave them three appearances: markings resembling the host species’ own eggs, markings resembling the other bunting species’ eggs, or no markings at all. Using the same foreign egg type with different patterns allowed the experiment to test how strongly the birds relied on spots and lines when deciding whether an egg belonged in the nest.

Rejection rose as egg patterns became less similar

Godlewski’s buntings rejected 45.5% of eggs with a host-like pattern, 78.6% with the other bunting’s pattern and 91.7% of pure-white eggs. Yellow-throated buntings showed the same progression, rejecting 40%, 87.5% and 100%, respectively. The yellow-throated buntings also showed stronger discrimination among the three pattern types.

Egg markings were the key recognition cue

The results show that egg markings are an important visual recognition cue for both species. Foreign eggs that resembled the host’s normal pattern were accepted much more often than eggs with unfamiliar markings or no pattern, while the intermediate rejection of the other species’ pattern shows that recognition was not simply a choice between patterned and unpatterned eggs.

Both buntings are potential hosts of common cuckoos but are only rarely recorded as parasitised. The authors argue that variation in egg-pattern features, together with how sensitively hosts respond to those differences, may be important antiparasitic adaptations. The study therefore links the visible “signature” of an egg to a concrete behavioural defence: whether a bird accepts or rejects the foreign egg.

Sources and image credit

  1. Zhang, Y., Wang, L., & Liang, W. (2026). Experimental evidence for egg signature recognition in two bunting species rarely parasitized by cuckoos. Journal of Ethology, 44(2), 181–188. https://doi.org/10.1007/s10164-025-00883-3Primary peer-reviewed research article; published 3 January 2026.

Image: Jargal Lamjav — Godlewski's bunting photographed in Mongolia on 3 September 2014; representative species image, not a bird from the 2026 experiment. Source: Wikimedia Commons. · CC BY 2.0 · Source

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