Welcome to DU!
The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.
Join the community:
Create a free account
Support DU (and get rid of ads!):
Become a Star Member
Latest Breaking News
General Discussion
The DU Lounge
All Forums
Issue Forums
Culture Forums
Alliance Forums
Region Forums
Support Forums
Help & Search
Massive southern invasions by northern birds linked to climate shifts
http://unews.utah.edu/news_releases/boreal-bird-irruptions/[font face=Serif][font size=5]Massive southern invasions by northern birds linked to climate shifts[/font]
[font size=4]A teeter-tottering climate pattern is behind the phenomenon of boreal bird irruptions – when flocks move far beyond their normal range.[/font]
[font size=3]May 11, 2015 – With puzzling variability, vast numbers of birds from Canada’s boreal forests migrate hundreds or thousands of miles south from their usual winter range. These so-called irruptions were first noticed by birdwatchers decades ago, but the driving factors have never been fully explained. Now scientists have pinpointed the climate pattern that likely sets the stage for irruptions – a discovery that could make it possible to predict the events more than a year in advance.
The researchers found that persistent shifts in rainfall and temperature drive boom-and-bust cycles in forest seed production, which in turn drive the mass migrations of pine siskins, the most widespread and visible of the irruptive migrants. “It’s a chain reaction from climate to seeds to birds,” says atmospheric scientist Court Strong, an assistant professor at the University of Utah and lead author of the study.
Many seed-eating boreal species are subject to irruptions, including Bohemian and cedar waxwings, boreal chickadees, red and white-winged crossbills, purple finches, pine and evening grosbeaks, red-breasted nuthatches, and common and hoary redpolls. The authors focused on the pine siskin, a species featured prominently in earlier work on irruptive migrations.
Previous studies have found evidence that irruptions are triggered by food shortages caused by the large-scale collapse of seed production in northern pine, spruce and fir forests.
…[/font][/font]
[font size=4]A teeter-tottering climate pattern is behind the phenomenon of boreal bird irruptions – when flocks move far beyond their normal range.[/font]
[font size=3]May 11, 2015 – With puzzling variability, vast numbers of birds from Canada’s boreal forests migrate hundreds or thousands of miles south from their usual winter range. These so-called irruptions were first noticed by birdwatchers decades ago, but the driving factors have never been fully explained. Now scientists have pinpointed the climate pattern that likely sets the stage for irruptions – a discovery that could make it possible to predict the events more than a year in advance.
The researchers found that persistent shifts in rainfall and temperature drive boom-and-bust cycles in forest seed production, which in turn drive the mass migrations of pine siskins, the most widespread and visible of the irruptive migrants. “It’s a chain reaction from climate to seeds to birds,” says atmospheric scientist Court Strong, an assistant professor at the University of Utah and lead author of the study.
Many seed-eating boreal species are subject to irruptions, including Bohemian and cedar waxwings, boreal chickadees, red and white-winged crossbills, purple finches, pine and evening grosbeaks, red-breasted nuthatches, and common and hoary redpolls. The authors focused on the pine siskin, a species featured prominently in earlier work on irruptive migrations.
Previous studies have found evidence that irruptions are triggered by food shortages caused by the large-scale collapse of seed production in northern pine, spruce and fir forests.
…[/font][/font]
2 replies
= new reply since forum marked as read
= new reply since forum marked as read
I had to look it up because it was so cool. 
