Weather and Songbird Migration
Primer by Ornithologist Dr. David
How to read the weather from a songbirds's point
As I am sure you are aware, weather plays a very important role in bird migration.
This spring, I will teach you how to read a weather map to try to predict areas of
the country that might see large numbers of migrants landing.
The Weather Channel
Let's start by looking at the general features of a weather map. The H's
and L's represent high and low pressure centers,
areas of swirling air.
- The air around a high pressure center circulates clockwise.
- The air around a low pressure system moves counter-clockwise .
The colored lines represent fronts: dividing lines between cold and warm
- Blue lines represent cold fronts, with
warm air in front (to the right of) the line and cold air behind (to the left of)
it. (Click for more information about cold fronts by U.
of Illinois or USA
- The red line is a warm front, with
colder air in front of it and warm air behind. (Click for more information
about warm fronts by U.
of Illinois or USA
So what does this all mean for birds?
Watch the High Pressure Systems
Birds want to fly with a tailwind to help them travel farther. In the spring,
this means winds moving south to north. Headwinds, wind moving north to south (in
spring), make it too difficult for birds to fly, so they are forced to land. Bad
weather, such as heavy rain, also forces birds to land.
Since highs follow cold fronts, birds will be forced
to land immediately following the passage of a cold front. After the high has moved
east, usually a day or two later, the birds have tailwinds and take off again.
Winds Associated With High Pressure
- On the right side of a high pressure system, the winds are coming from
the north, so migrants land.
- On the left side, the winds are from the south, so birds take off
The air around a high pressure center circulates clockwise.
Flags show direction wind is blowing from.
(Click on face of map to enlarge.)
Graphics Credit: Unisys Weather
So why don't birds use low pressure systems?
The reason is that low pressure systems often bring bad weather with them, so even
though the winds may be right, flying conditions are not good.
Is Today a Good Day for Migration?
Check out the Current
Surface Map and test your skills. Find the high pressure systems and look at
the wind direction.
Dr. David A. Aborn
See USA Today's Amazing Weather Graphics!
These weather concepts can be very difficult to visualize. The following illustrations
help to simplify a complicated topic:
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