2017 Climate March protester holds up an anti-Rick Snyder sign on the Flint water crisis.
Several studies have shown that birds migrate sooner in the spring when the world is warming.
Last year, when a research team at the University of Michigan reported that American migratory birds had grown smaller, and their wings somewhat longer, in the past four decades, scientists wondered if they could see the fingerprint of previous spring migrations.
‘Scientifically, this is really the most interesting and novel finding,’ said evolutionary biologist and ornithologist Brian Weeks, one of the main authors of the new study published in the Journal of Animal Ecology.
“We know that bird morphology has a major effect on the efficiency and speed of flight, so we became curious whether the environmental pressure to advance spring migration would lead to natural selection for longer wings,” said Marchiesa Zimova, an evolutionary biologist at the University of New York.
Both the new study and the 2020 study, which looked at changes in body size and wing length, were based on analyses of about 70.000 bird specimens belonging to 52 species in the Field Museum.
But in the previous study no investigation was carried out, to see, whether the changes in body height and wing length were due to fluctuations in migration caused by climate.
In the time, they connected body size measurements to warmer temperatures in bird breeding spots.
For each 52, the researchers reckoned temporal trends in morphology and changes in the amount of time and migration.