2023-09-03 13:00:10
A dark-eyed junco on the campus of the University of California, Los Angeles, in April 2017. SAMUEL BRESSLER
The Covid-19 has not only made people unhappy. We now know that many wild species have taken advantage of the periods of confinement caused by the pandemic to regain possession of territories, like the famous pumas frolicking in the streets of Santiago de Chile. But what regarding animals already accustomed to living in a human environment? And since all good things must come to an end, how did they react to the return of humans, once this period of “anthropause” was over?
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To address these two questions, a team from the University of California at Los Angeles (UCLA) monitored the behavior of a species of passerines that have resided on campus for nearly twenty years: the dark-eyed juncos. An almost imposed ordeal for Eleanor Diamant and her mentor Pamela Yeh. Since the 2000s for the second, 2017 for the first, the two ecologists have been studying the adaptation to the urban ecosystem of these birds, which passed forty years ago, without anyone understanding why, from the pine forests from the mountains of California to the cities of the coast, and from a migratory way of life to a sedentary behavior.
“A priori, observing them in a city without humans was not what we had plannedsays Eleanor Diamond. But such an opportunity only – hopefully – comes once in a lifetime. We mightn’t miss that. » Well it took them, as the article they published shows, August 22, in the magazine Proceedings of the Royal Society B. Because nothing happened as the two biologists had planned.
Two possible mechanisms
All the studies confirm this: “urban” animals are less afraid of humans than “field” animals. The rural juncos thus fly away when one approaches less than 3.50 meters, the urban ones only scamper at 1.60 meters. The reason ? Two theories clash: either the birds get used to our presence – we talk regarding habituation – or it is the less fearful who have chosen to settle among us. According to the first theory, birds facing confinement should regain their original caution and then become accustomed to our presence once the measures are lifted. According to the second, the sparrows, already selected for their bravery, should see their behavior unchanged, both by the absence and by the return of humans.
Place your bets… It’s lost! The measurements carried out on nearly seventy individuals showed that, during confinement, the birds did not modify their behavior in any way. But – and this is the essential surprise – once researchers and students return to the UCLA campus, the birds are even less frightened than before or during the pandemic. You now have to approach them within a meter for them to fly away.
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