[Animals] Birds are nesting a month earlier than a century ago due to global warming

[FNX Magokiler]

Although there is no temperature data going back 100 years, a group of researchers turned to an indicator of temperature, the amount of carbon dioxide (CO2) in the atmosphere.

Many bird species are laying their eggs an average of 25 days sooner than a hundred years ago.

A new study published in the Journal of Animal Ecology, based on data from the historical archive of eggs from the Field Museum of Natural History in Chicago, United States, showed that among the 72 species analyzed, about a third nested earlier and earlier. .

Since climate change has affected animals, the researchers considered rising temperatures to be a possible explanation for this change in bird nesting.

But, there is no consistent temperature data for the region going back to that time, so they turned to a proxy for temperature, the amount of carbon dioxide (CO2) in the atmosphere.

"We couldn't find a single source of long-term temperature data for the Midwest, which was surprising, but you can approximate temperature with carbon dioxide levels, which are very well documented," says author John Bates. main in a statement.

The amount of CO2 in the atmosphere over time is reflected in temperature trends, and the researchers found that it also correlated with changes in egg-laying dates.

 

 

“Global climate change has not been linear during this period of almost 150 years and therefore, it is possible that the species have not advanced their laying date in a non-linear way as well (…). We found that the simulated data was very similar to the observed data,” explained Mason Fidino, ecologist and co-author of the study.

The changes in temperature are only a few degrees, but they translate into the flowering of different plants and the appearance of insects, which could affect the food available to the birds. The new nesting dates could cause both species to compete for food and resources.

John Bates became interested in studying the egg collections at Chicago's Fields Museum after editing a book on the subject.

"Egg collections are a fascinating tool for us to learn about bird ecology over time," Bates said.

 

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