Climate change: beautiful tits lay eggs earlier

These birds make a great subject for ecological study, as they are easy to use man-designed nesting boxes, easy to reproduce, do not stray far from their place of birth, and are not concerned with having scientists.

The latter can mark a large number of chicks (with rings on their legs) to follow them throughout their lives.

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In the spring of 1947, biologists from the University of Oxford began observing the population of large tits in this Oxfordshire forest, which over time became a real -life laboratory. On April 27, they witnessed the laying of the first egg.

This is the beginning of a long, ongoing relationship between the bird population and generations of researchers.said the authors in a press release published by the University.

In the spring of 2022, the first egg of the year arrived on March 28, almost exactly a month earlier than its predecessor from 75 years ago, a trend that has lasted over the years.

This change is a clear sign of the effects of climate change on one of our most familiar forest and garden birds. It is studies of this type that allow us to determine the consequences of changesnotice biologists.

The spawning timing of species is influenced by several factors such as climate, social interaction and health of forest trees, whether researchers are beginning to understand in terms of vulnerability and potential resilience to climate change.

The biologists, who tracked each baby bird by recording the exact date when the females laid eggs and the date of hatching their eggs, said they noticed an early trend in the timing of the seasons. behavior.

In fact, according to them, tits only adapt to changes in their food chain. For example, the worms they eat appear earlier in the spring, because the leaves of the trees they eat also appear earlier.

A goldmine of information

Thanks to the foresight of the initiators of the study and the work of several generations of researchers in the field, we have access to a unique record that provides valuable information on the ecology and behavior of a bird population. in naturesaid John Krebs, professor emeritus of zoology, who completed his doctorate in Wytham’s chickadees in the 1960s.

Researchers at Oxford are gathering breeding data from 1,209 nesting boxes as well as information on several ecological forest indicators.

Over the years, new technologies have been added to the working tools of biologists, including electronic beacons, cameras, remote sensing tools and genetic tests to compile the genome of birds.

At least 70 doctoral theses have been completed since the project began and at least 350 studies have been published in scientific journals.

Last March, American scientists associated with the Field Museum of Natural History in Chicago published a study on Journal of Animal Ecology (New window) (in English) which showed that some bird species in the United States nest and lay eggs a month earlier than a hundred years ago.

According to their results, a third of the 72 species of birds studied the nest and laid eggs on average 25 days earlier than a century ago.