Sierra Summit

Conversations and observations about California's mountains

September 25, 2009
Sierra Nevada birds and climate change
WesternBluebird2.jpg
The more they look, the more scientists find the signposts of climate change across the California landscape. 

In the Sierra, such signals have been detected in more destructive wildfire, earlier spring run-off and the movement of small mammals - such as the alpine chipmunk - uphill toward more hospitable environments. 

A new study - published in the online journal Proceedings of the National Academy of Sciences earlier this month - has turned up more evidence in the behavior of birds, such as the western bluebird, show here.  

The study found that 48 of 53 Sierra species - including the bluebird - have adjusted to climate change over the past century by moving to sites with more desirable temperature and precipitation conditions. 

Some birds shifted to warmer locales while others preferred chillier habitats, the study found. Overall, 82 sites surveyed have seen an average 1.4 degree Fahrenheit temperature increase and nearly a quarter of an inch more rainfall during the breeding season since the early 1900s. The study builds upon the pioneering field work of  U.C. Berkeley zoologist Joseph Grinnell who traveled extensively across the Sierra between 1911 and 1929 and meticulously recorded what he saw. As our climate changes, the study found, birds tend to seek out conditions that existed in habitats - or ecological niches - that Grinnell documented and wrote about in his journals. 

Certain species, such as the Dusky Flycatcher and Green-tailed Towhee were more sensitive to temperature changes, while others, including the Yellow-rumped Warbler and Lazuli Bunting  reacted to precipitation changes. About a fourth of the species studied responded to both temperature and precipitation. 

"Understanding how species will respond to climate change allows us to take steps now to restore key habitats and create movements corridors that will help them respond to the changes we have coming," said Morgan Tingley, lead author of the study and a Ph.D. student at U.C. Berkeley, in a press release. 

To read the actual paper, click on this link:


Photo courtesy of Morgan Tingley








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About Sierra Summit

The Author
Tom Knudson lives in the Sierra Nevada and travels widely throughout the range. His hobbies include fly-fishing, backpacking and cross-country skiing. He is the recipient of numerous journalistic awards, including two Pulitzer Prizes, one for a 1992 Sacramento Bee series "Sierra in Peril," a watershed work about environmental threats to the mountain range. E-mail Tom at tknudson@sacbee.com.

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