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Cuckoo Finch trapped at Polokwane Bird Sanctuary, Limpopo, South AfricaCredit: B. Attard/CC BY-SA 3.0
A new study published in Proceedings of the National Academy of Sciences (PNAS) has discovered an ingenuous trick by the African cuckoo finch to transfer her parental responsibilities to other birds.
“They do this by laying similar looking eggs in the nests of other birds,” said Michael Sorenson, the lead researcher and associate dean of the Faculty of Natural Sciences at the College of Arts and Sciences at Boston University.
Cuckoo finches are obligate brood parasites, which means they only reproduce by parasitizing the parental care of other bird species, Sorenson explains. This behaviour evolved in African finches as early as 10 million years ago, and the lineage now includes about 20 parasitic species, including 19 Vidua species and the cuckoo finch, according to the research.
The team sampled genetic data collected from cuckoo finches in the field in Zambia in southeastern Africa. “Broadly, we wanted to test whether there is a genetic basis for the extensive variation in egg color and pattern observed in cuckoo finches, and more specifically whether cuckoo finch females that specialize on different host species—and lay eggs that mimic these hosts—can be distinguished genetically,” Sorenson said.
The researchers established that females associated with different hosts belong to distinct female lineages, that have been co-evolving with their respective hosts for two million years or more. In an ‘evolutionary arms race’, any time the hosts evolve the ability to distinguish intruder eggs, the cuckoo finch evolved egg mimicry to evade detection by the host, the research reveals.
