Warmer weather favors “weedy” species of birds

June 10th, 2009 - 2:01 pm ICT by ANI  

Washington, June 10 (ANI): An analysis has revealed that warmer weather has favored “weedy” species of birds, those that are adapted to a wide range of habitats and therefore easily extend their ranges.

Ecologists at the University of California, San Diego, US, did the analysis.

Larger birds, which are typically better disperses than smaller species, seem to have gained an advantage, according to the analysis.

“The changes, at least initially, are likely to favor generalist species, those in the best position to respond to changes,” said Frank La Sorte, a post-doctoral fellow at UC San Diego and first author of the paper.

“It’s going to be difficult using existing spatial ecological patterns to predict the outcome of climate change,” he added.

The team based their assessment on the annual Christmas Bird Count, an event organized by the National Audubon Society in which volunteers note which birds are present within a 24 kilometer wide circle in their communities over a 24-hour period in early winter, relying on either sight or sound to identify the species.

The team found 404 sites throughout North America where birders surveyed every year between 1975 and 2001.

Over that period of time, the average annual temperature of these communities increased by nearly one degree Celsius.

As spatial models predict, the numbers of species counted at each site grew as temperature climbed.

But, that increase could be attributed to larger and more widespread species becoming more common, a pattern not reflected by differences between ecological communities found in warmer versus cooler parts of the world.

The observation suggests that weedy species may win in a warmer world, at least initially.

But, it also warns ecologists that they may need to revise their models when planning conservation in the face of global climate change.

According to Walter Jetz, associate professor of biology at UC San Diego and senior author of the research paper, “Biodiversity is under severe threat from climate change, and the lack of long-term data makes accurate forecasting of likely impact notoriously difficult.” (ANI)

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