How Climate Patterns Thousands of Miles Away Affect US Bird Migration

Narration: Katie Jepson

Transcript:

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In the United States,

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a not-so-silent spring marks

the arrival of several billion

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birds migrating northward

from Central and South America.

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But curiously enough, the exact

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timing of this journey varies each year.

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So why is that?

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The key to this mystery may not lie in

looking at the traditional flyways,

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but instead in radar, climate models,

and a little bit of math.

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At the Global

Modeling and Assimilation Office,

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we routinely produce a comprehensive

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climate data set by combining

observations and models,

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and these are freely

available to the public.

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This data can be used to explain

the characteristics

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of ecosystems,

like bird migration patterns.

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In fact, by using a network of 143

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NOAA radar stations

across the continental United States,

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the team analyzed 23 years of data

to see if they could group stations

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that had similar year-to-year variability

in migration observations.

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And this is different

from the concept of flyways.

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This is specifically looking at which

radar stations across the United States,

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in what regions have a similar

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variability in bird migration timing.

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What they found is that the U.S.

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can be divided into two regions -

east and west, each with its own

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specific pattern of variability

of migratory bird arrival times.

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So now that we have divided

the continental United States

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into two regions,

we can look at each region specifically

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and understand the

climatic drivers of this region.

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The team found that the

behavior of Rossby Waves,

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huge waves of high-latitude westerly

winds, was a major influence

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for bird migrations in the East.

As Rossby Waves

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are triggered, particularly

those in the tropical Pacific,

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they influence climate patterns

and bring warm temperatures to the eastern

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United States, which in turn correlates

with earlier arrivals of migratory birds

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in that region.

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Cold temperatures

have the opposite effect.

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Variations in the West, however, seem

to be linked to more regional

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climate conditions, such as sea surface

temperatures of adjacent waters.

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In this study, we tried to highlight

the fact that we can use our data

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for applications that would bridge

climate science with other disciplines.

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The team hopes that future research

will build upon this study

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to help us better understand how changes

in the climate impacts specific

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migratory bird species.