The Birds On Radar

The twice-yearly migration of millions of birds from warmer climates to colder northern regions has always fascinated me.  It would be like half the USA getting up and walking a few hundred miles twice a year.


And it shows up on weather surveillance radar quite well at times.  We notice it here on the Portland radar from early-mid spring and then again in early-mid Fall.  You can see the echoes suddenly appear right after sunset, rise in height, and peak out around 8,000′ or so.

Tonight was a great example, the last of the daytime showers were fading away at sunset, moving from NORTH to SOUTH.   Then right after sunset the radar screen fills in with “targets” moving from SOUTH TO NORTH.  Here is the VAD wind display from the Portland radar around 7pm:


The wind arrows are all northerly up to around 12,000′, then no echos to get a speed/direction from above that level.

Then the same display around 11pm:


The arrows are all southerly or southeasterly, probably the birds flying straight north contaminated a bit by the northerly flow of the atmosphere?  The southerly flow seems to top out around 7,000′ too.  And how do we know the actual wind direction didn’t suddenly shift through thousands of feet of atmosphere in just a few hours?  All models show the northerly flow continuing through another 12+ hours.

Most birds prefer to migrate at night due to smoother airflow (no daytime heating for strong up/down motions), and they need to eat during the day down on the ground.

It doesn’t take that many birds to make a radar show “rain” (what it looks like to you).  Think of the surface area of a flock of geese or ducks compared to raindrops.  Or dozens of flocks of smaller birds scattered around the region.  Several studies have been done showing 20-30 dBZ echoes equal 200-1800 birds per CUBIC kilometer.  That’s a cube 1 kilometer  wide/high.  Lots of birds!

You can read more about it here:

By the way, there is a movie called WINGED MIGRATION (a documentary) produced about 10 years ago using hand-raised birds. They follow the birds (usually geese) while flying and migrating using some sort of very light aircraft. Or, actually I suppose the birds follow the aircraft since they imprinted on humans at hatching.  That means they think humans are part of their family. Now, believe me, this is no “party movie”, actually it’s REALLY slow, but great visuals for little kids to watch. Filming was done all over the planet. Here’s a clip for a little mid-day relaxation:

I like how they have short conversations with each other while flying

Chief Meteorologist Mark Nelsen

18 Responses to The Birds On Radar

  1. Sifton says:

    80 degrees in the 7day?! BEAUTIFUL!!! Where’s your Moses now Jesse?!?

  2. High Desert Mat says:

    Maybe we should start charging those Canadiens to use our airspace. Lol

  3. archangelmichael2 says:

    My comment got erased by being forced to log in on word press.

    Has anybody seen the one bird movie where the birds attack people and try to take over this coastal Northern California community?

    The intro is funny because it shows the guy driving on highway 1 and the birds in the cage lean with the curves.

    Highway 1 used to be more curvy then today but half of it got washed out from heavy rain during the 80s so what you see today half of it is not the original.

    Southern California’s highway 1 may be a different case however going thru Big Sur.

  4. archangelmichael2 says:

    Anybody ever seen that one bird movie from the 60s where the birds go crazy attacking people?

    I only saw the first half because according to Dad it’s more scary then even Jurrasic Park which is one of the top scariest films. M

    The bird movie is set on Northern California coast which the opening is funny. It shows the car driving with some birds in a cage leaning to the curves on the road.

  5. alohabb says:

    If you go to the ODOT website, you can see daily the migration of bird brains.

  6. schmit44 says:

    When will the new podcast be ready?

  7. chuck on mt scott says:

    We humans do migrate twice a year. By the gazillions. Northeasterners migrate to Florida and surrounding areas. Northwesterners migrate to Arizona and areas around. When lived in Florida, we called then “Snow Birds” 🙂

  8. runrain says:

    If Bodega Bay had this technology back in the 60’s, Alfred Hitchcock may have not have turned out to be the famous director he was. 🙂

  9. bgb41 says:

    4/16/2013 Oregon (All) Temperature Summary

    High:63 at DW9526 King City( 160 ft) & NATRON(518 ft) & BROOKS(187 ft) & W7APD Keizer(138 ft) & US30 at Rocky Po(56 ft) & Tillamook(63 ft) & DW2245 Hillsboro(180 ft) & Forest Grove(200 ft)
    Low: 46 at NEWPRT Cape Foul(1024 ft) & Newport(30 ft) & DW2435 Helix(1581 ft)

    High:18 at HOWARD Mt Howard(8150 ft)
    Low: 11 at ANTELOPE (6460 ft ) & HOWARD Mt Howard (8150 ft )

    Largest Diurnal Change: 29 degrees
    EW2396 Hillsboro (63/34 ) (430 ft )
    Wasco Junction ( (55/26) (1100 ft)

    Heaviest Rainfall:
    0.37″ at WICKIUP WEATHER(4358ft)

  10. W7ENK says:

    I see no birds… o_O

  11. Like the VAD wind profile display….

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