how many effects does climate change have on nature? Countless. In birds, moreover, it brings about a revealing change in behavior. Birds now nest a month earlier than a hundred years ago. The study that confirms this was published in the Journal of Animal Ecology.
One-third of the bird species nesting in Chicago have advanced egg laying. The average is 25 days. “Egg collections are a fascinating tool. We learn about the ecology of birds over time,” John Bates says in a statement. He is curator of birds at the Field Museum and lead author of the study. “We look at trends over the last 120 years. It helps to know how climate change affects birds.”
The museum’s egg collection itself occupies a small room crammed with floor-to-ceiling cabinets. Most were collected a century ago. They are stored in small boxes that tell what type of bird they belong to.
“These natural historians were amazing. They were very attuned to when birds were beginning to lay eggs.”
Bill Strausberger, a research associate at Field, had worked for years studying thrushes. He closely examined their nests. “I’d go out every spring. I would look for as many nests as I could and see if they were parasitized or not. He had modern nesting data,” Bates says. Chris Whelan, an evolutionary ecologist at the University of Illinois at Chicago, also contributed.
“Finding nests and following their fate to success or failure is time-consuming and challenging,” Whelan says. With the samples, they did the analysis. One-third of the Chicago species nested earlier and earlier.
Birds now nest a month earlier, most likely because they adapt to times when they have more food. The amount of carbon dioxide in the atmosphere had an influence. Temperature changes are apparently small, only a few degrees. But they translate into the flowering of different plants and the appearance of insects. This could affect the food available to the birds.