Birds Are Laying Eggs Earlier Likely Due to Climate Change

It’s an annual harbinger of spring: Birds singing, building nests, and laying eggs. But the timetable has been gradually changing. A new study finds that many bird species are building their nests and laying eggs nearly a month earlier than they did a century ago. Researchers compared bird egg information from museum collections with recent bird behavior observations and found that about one-third of the bird species that nest in Chicago have moved their egg-laying to an average of about 25 day

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The likely culprit, the researchers believe, is climate change. "Much data collected over the last few decades have shown that many species of animal and plant are changing the timing of their ecologies—leaf-out and flowering of plants, timing of migration of birds and some insects, and timing of nesting ecology of birds," co-author Chris Whelan, an evolutionary ecologist at the University of Illinois at Chicago, tells Treehugger. John Bates, the curator of birds at the Field Museum, realized that the egg collections of his and other museums hold old but accurate records on the timing of nesting of many bird species. Bates suggested comparing modern nest efforts with nesting behaviors associated with eggs in the museum's collections. Some of that data went back to the 1870s. Bates, the study's lead author, became interested in studying the museum's egg collection after editing a book about eggs. "Egg collections are such a fascinating tool for us to learn about bird ecology over time," he says. "I love the fact that this paper combines these older and modern datasets to look at these trends over about 120 years and help answer really critical questions about how climate change is affecting birds."