The works, carried out over a period of 23 years (2005-2019) thanks to a partnership between scientists from the UPV/EHU and the Center for Functional and Evolutionary Ecology of Montpellier (CEFE-CNRS), focused on two populations of blue tits in the south of France, one located on the outskirts of Montpellier and the other north-west of the island of Corsica.
Each year between 2005 and 2019, all breeding blue tits from each population were captured. As a result, researchers from both establishments were able to collect more than 5 800 observations on the coloration and other characteristics of blue tits.
The blue tit is characterized by its striking coloration: a blue crest and a yellow breast. The results obtained in the study show a decrease in the two populations of blue and yellow coloration between 2005 and 2019. In other words, the blue crests and yellow breasts of blue tits in these two populations are on average less colorful at this second than at the minute of the search. began.
“Our work suggests that environmental change, and more specifically climate change, may be the main reason why birds such as the blue tit are experiencing a change in their physical characteristics, more precisely in the luminosity and intensity of their coloration,” said David López-Idiáquez, researcher in the Department of Plant Biology and Ecology at UPV/EHU.
“A negative trend in terms of brightness and intensity of plumage coloration in both sexes and populations has been observed, although in Corsica this change is more climate-related,” explained Lopez. “The change in plumage color appears to be the result of a combination of an increase in temperature (1.23°C) and a decrease in precipitation (,64 mm), climate change would therefore be the potential trigger for this difference”, he said.
Change in species mating patterns
This may seem like a purely cosmetic change, but it’s Quite the opposite is true, as this change in plumage may have an effect on the species’ “mating patterns”. “In these birds, characteristics such as coloration function as signals to indicate to other individuals the quality of the specimen, which are decisive, for example, in matters of reproduction”, explained David López.
“This study was made possible by the continuous monitoring of the two populations of blue tits for more than years, which which highlights the importance of long-term studies to understand the effects of climate change on the ecosystems around us,” he said.
When there is a variation in the territory, the animal populations have 4 possibilities: the first is to undergo a genetic modification the second is to undergo a plastic change (change of physical characteristics without genetic changes) the third is to migrate and the last, to disappear. “It is important to emphasize that this change is not genetic but plastic, one of the ways of adapting to new environmental circumstances”, he stressed.
Change in our environment
“Since our environment is quite similar, although less warm, our birds could undergo the same change”, David surmised . “In any case, there are only four studies of this type in the world, and none of them have been carried out in the Basque Country. I think it would be very interesting to carry out more research like this- ci not only at the Basque level, but also at the national level”, he added.
David López-Idiáquez (Villajoyosa, 1988) is a postdoctoral researcher at the University of the Basque Country and at the Center for Functional and Evolutionary Ecology in Montpellier. His research interests focus on understanding how heterogeneity in environmental conditions alters evolutionary dynamics, particularly in ornamental traits. After graduating from the UPV/EHU, he obtained a doctorate in ecology from the Autonomous University of Madrid in collaboration with the Museum of Natural Sciences of Madrid.