Horneros build their mud nests cooperatively: in pairs. Half of the work is done by the female, and the other half is done by the male. Construction takes about 10 days, and One difference that caught the attention of bird watchers was the asymmetry in the architecture of the nest: some have the door more to the right and others to the left.
With the help of more than 1,200 people from Latin America and through a cell phone application, a team of scientists revealed that the asymmetrical architecture of ovenbird nests is not by chance. Now, after analyzing the images they received from observers from Uruguay, Paraguay, Brazil, Argentina and Bolivia, Nicolás Adreani, Lucía Mentesana, and Mihai Valcu, hypothesize that there are genetic traits that are transmitted from generation to generation that would contribute to pairs building nests with similar architecture. The study was published in the specialized journal Current Biology.
In most bird species, only one sex builds the nest. But the baker (whose scientific name is Furnarius rufus) are in the tiny group in which both male and female cooperate. It is a species native to South America, and they are known as “ogaraity” in Guarani or “tiluchi” in Bolivia. It is usually a symbol of unity and work.
The Argentine researchers Adreani and Mentesana, together with the programmer Tomás Córdoba Years ago, they created a free application for the cell phone (@nidohorneros on Twitter and Instagram) that allows data to be collected from the observations of horneros in a couple of minutes. This is how they launched a “citizen science” project that crossed the borders between countries: “We wanted to generate new knowledge about an emblematic bird species of South America”, he said in dialogue with Infobae Dr. Adreani, who works at the Max Planck Institute for Ornithology in Germany.
The ovenbirds build the nest with mud on utility poles, houses, or trees. In addition to mud, they use some plants and manure from other animals. Little was known about its architecture: rains or winds were thought to influence nest asymmetry. Therefore, the researchers invited citizens to participate through the application to clarify the issue.
More than 1,200 people participated by taking pictures of more than 12,600 nests in the 4.8 million square meters of the hornero’s distribution area in South America. According to Adreani, at the population level, 12% more nests were found with the entrance on the right than with the entrance on the left. That position of the nest entrance is also highly repeatable between different pairs of ovenbirds.
Therefore, according to the researchers “It is very likely that a pair always builds a nest with the same asymmetrical architecture, that is, the entrance is always on the same side”. Also, each pair builds the nest and uses it only once. It is possible to record several nests of a pair in successive years in an area and repeatedly measure the asymmetry of the nest of the same pair.
The lack of influence of environmental factors on nest asymmetry and the high pair-level repeatability suggests that an individual can only form an “asymmetric phenotype”. “We think it is possible that the remarkable repeatability of bilateral nest architecture has a genetic basis,” Mentesana stated. Although after raising this hypothesis, a new question is generated: Does the asymmetry of the nest depend on the two members of the pair or is it only decided by one?
consulted by InfobaeJuan Carlos Reboreda, biology and bird researcher at Conicet and the Faculty of Exact and Natural Sciences of the University of Buenos Aires (UBA), highlighted the study published in Current Biology. “It is the first large-scale citizen science project in South America that focuses on studying the hornero, and it has had a high level of participation.”
For the scientist, who has also published works on the hornero“the authors reject the possibility that the asymmetry in the nest architecture is random. That the nest is made with an asymmetric architecture does not necessarily have an adaptive value from the point of view of evolution. It could be a cultural effect, but the authors posit genetic transmission. An issue that deserves further study.
To build their sturdy nests, ovenbirds first make a base, then build the side walls and roof, and an internal dividing wall. inside the nests, the pairs lay the eggs and protect them from predators. “As ovenbirds only use the nest once, can be for minimize exposure of nestlings to parasites from previous broods”, explained Mindy.
Another characteristic of the horneros is that both the male and the female take care of the eggs inside the nest. “Bakers are not machirulos Like most birds pointed out Dr. Reboreda, with a look from the gender perspective that today advances with respect to the human species. “It will be interesting that the study continues so that it can be known who determines the construction with an asymmetric architecture, if it is the male or the female.”