Forecasting Bird Migration with Weather Radar and Models

From The Cliff Mass Weather Blog

We are now in the midst of the big bird migration time of the year and weather radar can help documents the huge flux of birds overhead.

But even more fascinating, we can skillfully predict bird migration using numerical weather prediction.

One of my favorite sites  to check out bird migration is BirdCast, run by the Cornell Laboratory of Ornithology.  I really appreciate this group and as an undergrad at Cornell I frequently visited their Sapsucker Woods Wildlife Sanctuary.

One of the wonderful things they have on their website is real-time bird migration maps based on the clever use of weather radar (see below).  Turns out that weather radar is a very effective tool for tracking birds, particularly when there is not much precipitation (when the National Weather Radars are in clear air mode).

The map below provides an example:  a real-time snapshot of bird migration at 12:50 AM PDT early this (Saturday) morning.  The colors shows the intensity of bird migration and the orange arrows provide the direction of migration (which can be determined from the Doppler weather radar signal!).  Not surprisingly, most birds are moving northward and the Pacific Northwest is an active migration route.    The largest migration is from Texas to Wisconsin.  By the way, the units of this map is THOUSANDS of bird per km line per hour.   That is a lot of birds!

To confirm the bird invasion, here is the composite radar image the night before (1:38 AM on May 1st).  Wow.  There was very little precipitation that night, so virtually all of this is birds. Keep in mind that there are major gaps in weather coverage (such as east of the Cascade crest).   You note lack of echos offshore…our feathered friends prefer to stay over land!

Our bird friends prefer to fly at night, and the Cornell migration graphic at 9:40 PM Eastern Time yesterday shows this, with the red line indicating the location of sunset at that time.  Very few birds while the sun is up (west of the line), lots of birds to the east of the sunset line.

But this site has even more!  It include forecasts of bird migration activity.    Using decades of radar information to provide migration ground truth, they correlated bird migration activity with forecat weather parameters (from NWS prediction models), day of year, and much more, using a machine learning algorithm. This approach is based on the work of Van Doren and Horton (Science Magazine, 2018) . To illustrate, here is the migration prediction for tonight (Saturday-Sunday), which includes the amount of forecast precipitation as well.

Less birds tonight..and that has to do with the change in the weather.   This bird forecast research noted above (Van Doren and Horton) found the bird migration correlates best with temperature (more migration with warmer temperatures), with precipitation also discouraging our feathered friends.  The strong front moving through today will result in both cooler temperatures and showers.  Thus, our migrating bird visitors will take a well deserved rest this evening.

Finally, I should mention that there is all kinds of fascinating information in that Van Doren an Horton papers, such as the annual variation in bird migration over the U.S. based on the weather radar data (see below).  Peak migration is in early-May, with a huge ramp-up in April…so we are very near the peak now.  Thus, watching the radar now is of particular interest for all bird lovers.

So during the next mild night this month, look up and imagine the thousands of birds that are moving northward above your head.  Kind of reassuring during these difficult times.

32 thoughts on “Forecasting Bird Migration with Weather Radar and Models

  1. Wow! As a fellow bird lover I say thanks to Charles Rotter for posting this informative and useful bird migration tracking article. Yes, I am a bird lover, especially wild goose in the slow cooker with some veggies, and a glass of chardonnay waiting for me. Thanks!

    • How do they know the date? The American white pelicans always seem to return to my area of Colorado by April 4.

      • Pelicans are my favorite shore bird. I love how they surf the updrafts coming off of rolling wave faces.

        • One of my favorites too. I saw about 10 this morning, all swimming or perched on an island in a pond. They’re so graceful in the air, especially when flying in formation.

        • Camping on the beach in Mexico we termed that the Mexican Air Force, watching them sweep along the front of a roller, wing tip feathers just barely roughing the water
          Majestic

      • They (American White Pelicans) are also arriving in the BC interior right now. The South Cariboo. 108 Mile Lake to be precise. Google it. Amazing birds.

        We get zillions of species through here. My favourite are Pine Siskins. Tough little critters.

  2. If you listen to the greenies, birds everywhere are going extinct. It’s nice to know that they still exist in vast numbers.

  3. In response to the pictured “Live Migration Maps”, …. I was surprised of the lack of “activity” along the Eastern Flyway from the Carolinas to the Canadian border.

    Must be those radar sites weren’t reporting “bird sightings”.

    “HA”, ….. is not the Cornell Laboratory of Ornithology located in Ithaca, New York …. with a few of those migrating Canadian geese a “honking” right over top their head? 😊

    • Same with some white pelicans (as mentioned above). Despite being a stones throw from Facebook headquarters, by the Dumbarton Bridge, they never get the memo and stay on the San Francisco Bay all year.

      The pink flamingo that moved in for a while a few years ago did eventually depart though.

  4. “Our bird friends prefer to fly at night”
    except hummers …
    And any others ?
    😉

  5. One thing I noticed is that the Canada Geese fly North in the morning and South in the evening. I have no idea how far they fly daily, but 50 miles would not surprise me. Here in New England, 50 miles N or S from your location puts you in a climate noticeably different. It seems to be worth the effort for the birds. In any event, their net migration is the difference between their morning and evening flights.

    For a wild and protected species, there sure are a lot of them in suburban areas and even in the housing subdivisions. All they seem to need is a bit of lawn and some water nearby. They do become quite the neighborhood fixtures. The big goose standing Sentinel Duty will get after you if you get to close to the flock. I bribed one with Fritoes Corn Chips. Geese *love* corn chips. They actually become quite friendly when you have food. Little did they realize I was “corn fattening” them.
    She Who Must Be Obeyed suspected what I was up to and told me that indeed, She would cook my goose.

    • TonyL – May 4, 2020 at 8:55 am

      One thing I noticed is that the Canada Geese fly North in the morning and South in the evening.

      That is probably because of where they “stopover” to rest and feed. They are migrating “creatures of habit” and have regular “stops” along their migration route.

      Now I don’t know as actual fact but I’m pretty sure most birds migrate during daylight hours simply because they have the same problem as airplane pilots do, especially “bush” pilots and pilots that use small or private airports.

      They don’t like “landing” in the dark.

      So, especially the waterfowl, are more likely to “takeoff” during daylight hours, …… fly all night long ….. and/or most of the next day (depending on where their next rest stop is) ….. and then land the next morning.

      On a clear or “moon lit” night it is no problem seeing where you are “flying”, …… but once you descend to 100 feet or so ……… you can’t see much of anything underneath you.

      Passenger Pigeons, billions of them, all migrated during daylight hours.

    • Just had to Google it to see how far they can fly in a day and was amazed to see the result but sort of makes sense when you think about it, especially if they fly for 12-14 hours a day or longer. I live in the remote mountains and sometimes hear them flying (and see them in the moonlight) in the middle of the night flying their huge V formation.

      “Canada geese fly at an average speed of about 40 miles per hour when migrating, but may increase their speed to 70 miles per hour if they catch a strong tailwind. Migrations can be as long as 2,000 to 3,000 miles, and the geese are capable of flying up to 1,500 miles in a single day if the weather is good.”

      https://forum.americanexpedition.us/canada-goose-information-facts-photos-and-artwork

  6. CTM-

    What an interesting ,enlightening, and enjoyable post in these trying times!

  7. Cliff is misinterpreting the Doppler radar data.
    That is atmospheric opacities due to sensitive radars modes (VCP 31) being enabled that then paints water vapor discontinuity boundaries (rapid humidity changes) and virga.
    He really needs to work with the NWS Radar Operations Center (ROC) operational weather guys who are monitoring and changing the modes (called VCP, volume coverage pattern modes) on each the WSR 88-D doppler radars especially at night.

    The current VCP at each are available here:
    https://www.roc.noaa.gov/WSR88D/Operations/VCP.aspx

    Cliff’s obvious favorite iis Langley Hill radar in SW Washington State that he got NOAA to install using their last operational spare radar to fill in coverage gap.
    It’s current VCP (as of this post time):
    103. Langley Hill WA (KLGX) VCP 215 AVSET SAILSx1 5/4/2020 16:58Z

    • For example, Cliff’s birds radar plot at 01338 AM, 1 May 2020 (= 01May2020, 0838 GMT) we can find the Portland WSR-88D VCP mode from the archive log: It reads:

      20200501 08:08,A,215
      20200501 08:14,B,35
      20200501 08:22,B,35
      20200501 08:31,B,35
      20200501 08:40,B,35
      20200501 08:49,A,215

      From this we can see that at the time Cliff “sees birds”, the radar was in Clear Air Mode, VCP 35 and had been since 0822 GMT (01:22 AM PDT). VCP 215 is a precipitation mode.
      Cliff’s birds taking flight are the radar operators changing the radar VCP to a clear air mode (31, 32, or 35) to assist the operational forecasters. Cliff is seeing moisture reflections (water vapor higher & humidity) over the mountains and coastal ranges NOT birds.

      • actually the VCP went to VCP 35 from VCP 215 earlier at 08:14 GMT (01:14 AM PDT) not 0822.

    • For example, Cliff’s birds radar plot at 01338 AM, 1 May 2020 (= 01May2020, 0838 GMT) we can find the Portland WSR-88D VCP mode from the archive log: It reads:

      20200501 08:08,A,215
      20200501 08:14,B,35
      20200501 08:22,B,35
      20200501 08:31,B,35
      20200501 08:40,B,35
      20200501 08:49,A,215

      From this we can see that at the time Cliff “sees birds”, the radar was in Clear Air Mode, VCP 35 and had been since 0822 GMT (01:22 AM PDT). VCP 215 is a precipitation mode.
      Cliff’s birds taking flight are the radar operators changing the radar VCP to a clear air mode (31, 32, or 35) to assist the operational forecasters. Cliff is seeing moisture reflections (water vapor higher & humidity) over the mountains and coastal ranges NOT birds.

  8. Nice post. In New Zealand we look forward to the migration of the Godwits from Alaska to new Zealand in September. It is the longest bird flight annually, and they complete the journey without stopping or touching down. About nine days and nights non-stop.
    No food or water stops over the11500km.

    The timing of departure varies slightly each year, and no one understands the trigger for departure.
    Regards
    https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.sciencelearn.org.nz/videos/721-the-longest-flight&ved=2ahUKEwixm9yV4ZrpAhVBeH0KHYmcAhkQwqsBMBB6BAgHEAQ&usg=AOvVaw2TyEqcBrv9aIX8VtA-Nrmx

  9. Thank you Charles.

    “So during the next mild night this month, look up and imagine the thousands of birds that are moving northward above your head.”

    … and wear a broad-rimmed hat.

  10. Great post. If you like the subject, there is a wonderful video just released on Smarter Every Day about bird murmerations, that cloud like flying that some species like cranes demonstrate, and how it can be modeled with a few simple behavioral rules.

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