Featured Research

from universities, journals, and other organizations

Bigger birds in central California, courtesy of global climate change, study suggests

Date:
November 1, 2011
Source:
San Francisco State University
Summary:
Birds are getting bigger in central California, and that was a big surprise for researchers. They uncovered the trend while working analyzing data from thousands of birds caught and released each year at two sites near San Francisco Bay and Point Reyes National Seashore. The study found that birds' wings have grown longer and birds are increasing in mass.

Birds are getting bigger in central California, and that was a big surprise for Rae Goodman and her colleagues.
Credit: © Celso Diniz / Fotolia

Birds are getting bigger in central California, and that was a big surprise for Rae Goodman and her colleagues. Goodman uncovered the trend while working as a graduate student for Associate Professor of Biology Gretchen LeBuhn, analyzing data from thousands of birds caught and released each year at two sites near San Francisco Bay and Point Reyes National Seashore.

The SF State scientists found that birds' wings have grown longer and birds are increasing in mass over the last 27 to 40 years.

What's making the birds bigger? The researchers think that the trend is due to climate change, but their findings put a twist in the usual thinking about climate change and body size. A well-known ecological rule, called Bergmann's Rule, states that animals tend to be larger at higher latitudes. One reason for this rule might be that larger animals conserve body heat better, allowing them to thrive in the generally colder climate of higher latitudes.

Under this reasoning, some scientists have predicted that animals would get smaller as Earth has warmed up over the past 100 years. But the study, published in the journal Global Change Biology, suggests that the connection may not be so simple.

Climate change may affect body size in a variety of ways, they note in their paper. For instance, birds might get bigger as they store more fat to ride out severe weather events, which are expected to be more common under global climate change. Climate change could also alter a region's plant growth, which may eventually lead to changes in a bird's diet that affect its size.

LeBuhn said she was "completely surprised" to find that the central California birds were growing larger over time. "It's one of those moments where you ask, 'what's happening here?'" The results were so unexpected, she said, that the findings made them take a step back and look more closely at how climate change could influence body size.

The bird data come from two long-term "banding stations" in central California, where a wide variety of birds are captured, banded about the leg with an identification tag, and weighed and measured before being released. Many of the same birds were captured each year, allowing the researchers at the sites to build up a unique database that could be used to track changes among the birds over several decades.

The researchers used data from 14,735 individual birds collected from 1971 to 2010 at the Palomarin Field Station, near the southern end of the Point Reyes National Seashore, by researchers from PRBO Conservation Science. Their study also included data on 18,052 birds collected between 1983 and 2009, from the Coyote Creek Field Station at the southern end of the San Francisco Bay by the San Francisco Bay Bird Observatory.

"At the time I started my research, a few studies had looked at body size changes in a few species in Europe and the Middle East, but no one had examined bird body size changes in North America," said Goodman, who graduated from SF State in 2010 and now teaches biology and environmental science at San Francisco's Jewish Community High School of the Bay.

"We had the good fortune to find an unexpected result -- a gem in research science," she added. "But we were then left with the puzzle of figuring out what was going on."

After testing and discarding a number of other explanations, Goodman and her colleagues were confident that climate change was behind the longer wings and bigger bodies in most of the birds. The birds may be responding to climate-related changes in plant growth or increased climate variability in central California, the researchers suggest in the paper.

The findings offer a glimpse at the potent effects of climate change across a wide range of species, LeBuhn said. "Even over a pretty short period of time, we've documented changes in important traits like body size, where we don't expect to see much flexibility."

"But in some ways," she added, "it gave me a little more hope that these birds are able to respond -- hopefully in time -- to changes in climate."


Story Source:

The above story is based on materials provided by San Francisco State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rae E. Goodman, Gretchen Lebuhn, Nathaniel E. Seavy, Thomas Gardali, Jill D. Bluso-Demers. Avian body size changes and climate change: warming or increasing variability? Global Change Biology, 2011; DOI: 10.1111/j.1365-2486.2011.02538.x

Cite This Page:

San Francisco State University. "Bigger birds in central California, courtesy of global climate change, study suggests." ScienceDaily. ScienceDaily, 1 November 2011. <www.sciencedaily.com/releases/2011/10/111031154127.htm>.
San Francisco State University. (2011, November 1). Bigger birds in central California, courtesy of global climate change, study suggests. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/10/111031154127.htm
San Francisco State University. "Bigger birds in central California, courtesy of global climate change, study suggests." ScienceDaily. www.sciencedaily.com/releases/2011/10/111031154127.htm (accessed October 2, 2014).

Share This



More Earth & Climate News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dolphins and Turtles Under Threat in Pakistan

Dolphins and Turtles Under Threat in Pakistan

AFP (Oct. 2, 2014) — The turtles and Dolphins of Pakistan's Indus river - both protected by law - are in a fight for their survival as man's activities threatens their futures. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com
Raw: Japan Volcano Rescue Video Released

Raw: Japan Volcano Rescue Video Released

AP (Oct. 2, 2014) — The Tokyo Fire Department released video of rescue efforts following Saturday's eruption of Mount Ontake in central Japan. It shows firefighters and military troops carrying injured people as plumes of smoke pour from the volcano behind them. (Oct. 2) Video provided by AP
Powered by NewsLook.com
Raw: 12 More Bodies Found on Japan Volcano

Raw: 12 More Bodies Found on Japan Volcano

AP (Oct. 1, 2014) — A dozen more bodies were found Wednesday as Japanese rescuers resumed efforts to find survivors and retrieve bodies of those trapped by Mount Ontake's eruption. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins