Birds migrate earlier, but some may be left behind as the climate warms rapidly

Many birds are arriving earlier each spring as temperatures warm along the East Coast of the United States. However, the farther those birds journey, the less likely they are to keep pace with the rapidly changing climate.

Scientists at Boston University and the Manomet Center for Conservation Sciences analyzed changes in the timing of spring migrations of 32 species of birds along the coast of eastern Massachusetts since 1970. Researchers at Manomet gathered this data by capturing birds in mist nets, attaching bands to their legs, and then releasing them. Their findings, published in Global Change Biology, show that eight out of 32 bird species are passing by Cape Cod significantly earlier on their annual trek north than they were 38 years ago. The reason? Warming temperatures. Temperatures in eastern Massachusetts have risen by 1.5 degrees Celsius (2.7 degrees Fahrenheit) since 1970.

Species, such as the swamp sparrow, that winter in the southern United States are generally keeping pace with warming temperatures and earlier leafing of trees. They migrate earlier when temperatures are warm and later when spring is cool.

Birds that winter further south, like the great crested flycatcher, which spends its winters in South America, are slow to change, though. Their migration times are not changing, despite the warming temperatures in New England.

There appears to be good reason for the difference between the short- and long-distance migrants. Because temperatures are linked along much of the East Coast of the United States—an early spring in North Carolina is generally an early spring in Massachusetts—the short-distance migrants can gain insight into when it will be warm further north. They can follow the flush of leaves and insects all the way to their breeding grounds each year. Long-distance migrants, though, do not have any good cue for whether it will be an early or late spring on the northern stretches of their migrations. Weather in South America has little to do with weather in New England.

Being slow to change in response to warming temperatures could have serious repercussions for long-distance migrant birds. This same research group has shown that plants are blooming earlier in Massachusetts than they did in the past. It appears that the short-distance migrants are keeping pace with this changing environment. However, long-distance migrants are being left behind; as temperatures continue to warm, they will probably experience environments increasingly different from the ones for which they are adapted. Other researchers have already noted that some long-distance migrant birds returning from African wintering areas to breed in Europe are now mistimed with their insect food supply. The inability of some birds to adapt to rapid climate change may be an important factor in some of the declines among songbird populations that have been documented in recent years.

Source: Wiley - Blackwell

   

• photojack - Jun 20, 2008
  • Rank: 2.8 / 5 (6)
  The British scientists have been noting these trends for an even longer period of time. And Bush tried to deny the reality of global warming? The Democrats have to take control and end this Bush nightmare once and for all. And our party must communicate clearly and quickly to counter the smear tactics and "swift boating" of our fair and morally upright candidates. Too many top-level Republicans have fallen, resigned or been involved in major scandals and we need to remind Americans of that. They are the party of big business and big corruption scandals. A clearly stated platform and clearly stated goals for the future of America need to be communicated, so people will make the obvious choice for Progressives, not Bush clones, like McCain!
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• D666 - Jun 20, 2008
  • Rank: 2.3 / 5 (6)
  Are you kidding? These birds are just dupes. They've bought into this global warming crap and think they have to migrate sooner. If they'd bother to check the facts, they'd know that it's actually cooling, winter's getting longer, the ice is increasing, and polar bears are doing just fine!
  
  Stupid birds.
  
  
  
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• wfl - Jun 20, 2008
  • Rank: 2 / 5 (5)
  One of the options for migratory birds is to stay put. All over the US there is living proof there is living proof of their ability to adapt to changing or new habitat in the form of the Canadian goose. All of the speculation about how climate change will adversely impact wildlife is so much crap.
  
  Where are the citations to peer reviewed research that show extinctions in modern times from climate variability? Is there any?
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