Red-cheeked cordon-bleu male shows his ability to collect nesting material
A red-cheeked cordon-bleu often holds a grass stem in its beak during courtship. It chooses the longest object it can get, Masayo Soma and colleagues found.
A male and female red-cheeked cordon-bleu work on their relationship continuously. They sing and dance for each other; dancing entails simply hopping up and down. Song and dance play a role in mutual mate selection and serve to strengthen the pair bond afterwards; a courtship session rarely results in copulation. Couples are close and male and female raise young together.
During courtship, birds often hold a grass stem or straw in their beak, and Masayo Soma and colleagues investigated the significance of this courtship element.
Grass nest
The red-cheeked cordon-bleu (Uraeginthus bengalus) is a songbird that lives in sub-Saharan Africa. It belongs to the estrildid finches, a group of species of which most have beautiful colour patterns. Many species strengthen the pair bond, like the red-cheeked cordon-bleu, with song and dance during which they may hold a grass stem. Males hold a stem during dance more often than females.
Previous research had shown that species performing a stem-holding display are mainly species in which males work intensively on building the nest. Many species of estrildid finches make a nest of grass; the males have the task of collecting the nesting material, while females remain on the nest and weave in the stems that were brought in. This is also the case in red-cheeked cordon-bleu.
The idea is therefore that a male holds a grass stem in his beak while dancing to show that he is well able to perform his task. For females, handling a grass stem does not have that meaning.
The longest
That idea is now gaining additional support. Because if a male intents to advertise his nest material collecting ability by performing nesting material holding display, a long stem is more convincing than a short one. And indeed: a long stem is preferred, red-cheeked cordon-bleus showed in choice tests. The birds, which are about 13 centimetres long, were offered strings of 5, 10 and 20 centimetres. They mostly chose a string of 20 centimetres. If they picked up a short string, they immediately threw it away.
The researchers did similar experiments with the star finch (Bathilda ruficauda, synonym Neochima ruficauda), an estrildid finch from northern Australia and also a grass nest builder, and got the same result.
The story is not yet complete. For instance, the researchers do not know whether a bird that displays with a long grass stem will get a better partner or be more successful in maintaining the pair bond. Moreover: it is not clear whether long stems are preferred for nest building. If not, then handling a long stem would serve to embellish the display rather than to prove collecting ability.
Willy van Strien
Photo: red-cheeked cordon-bleu (Uraeginthus bengalus). Carlos Vermeersch Santana (Wikimedia Commons, Public Domain)
See also: blue-capped cordon-bleu (Uraeginthus cyanocephalus), closely related to red-cheeked cordon-bleu, performs tap dance
Sources:
Soma, M., M. Nakatani & N. Ota, 2025. Choice of props for courtship dancing in estrildid finches. Scientific Reports 15: 219. Doi: 10.1038/s41598-024-81419-6
Soma, M., 2018. Sexual selection in Estrildid finches, with further review of the evolution of nesting material holding display in relation to cooperative parental nesting. The Japanese Journal of Animal Psychology, 68: 121-130. Doi: 10.2502/janip.68.2.2
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