Migration Report: 16 – 22 March 2012

Benjamin Van Doren The Cornell Lab Mar 23, 2012

Check out last week’s forecast, then read on to see how we did!

Last week’s BirdCast predicted another week of widespread migration and record early arrivals across the continent. The unsettled weather predicted to reach the mid-continent in mid-week prompted a mid-week alert about a coastal fallout on the Gulf of Mexico. In addition to widespread Ring-necked Ducks, arriving waterfowl were predicted in the Prairie Provinces, Franklin’s Gulls were expected to reach the Midwest, and Sage Sparrows, White-throated Swifts and Say’s Phoebes were expected west of the Rockies. A big push of Eastern Phoebes in the Great Lakes and Northeast was predicted to bring a widespread record-early arrival for that species, with others on its heels. Did BirdCast get a passing grade this week? Read on to find out!

See the week of migration in action in our radar animation, which shows consistent nocturnal movements in the East throughout the past week. For help interpreting these radar images, refer to our Understanding Birds and Radar: Part I story.

American Golden-Plovers pushed well into the Great Plains and Midwest, with one found as far east as Cape May, NJ


Conditions were not favorable in most areas for extensive movements early in the weekend through to the beginning of the week, particularly given the formation and subsequent passage of a reasonably well-organized cold front and the continued battering of the Pacific NW by storms. However, by mid to late week, as high pressure built in, portions of the central valley in CA, the desert SW, and the Great Basin experienced light nocturnal migration.  The Pacific NW, however, continued to experience largely unfavorable conditions for nocturnal migration through the forecast period.

Great Plains

Light to moderate migration (birds and presumably insects as well given the warm temperatures) occurred on radar over much of the region from the weekend up until the arrival of a substantial cold front early Monday, as warm southelry flow prevailed.  With the arrival of the front, migration shut down for the remainder of the forecast period as a result of the strong storms, precipitation, and unfavorable winds associated with frontal passage.  By Wednesday night and early Thursday, some light migration was again occurring in the far northern Plains states.

Upper Midwest and Northeast

Light to moderate migration was the norm for almost the entire forecast period in the Upper Midwest and Great Plains region, visible on radar stations across the area. Radars presumably show primarily birds, but given the unseasonable warmth, insects and aerial plankton were likely present as well. Several stalled frontal boundaries allowed favorable migration conditions to persist in many areas, facilitated as well by the relative scarcity of precipitation (other than a late weekend disturbance passing through the region that shut down movements in its path).  Additionally, the large frontal boundary responisble for shutting down movements in the Plains states did not push its way into this region, allowing southerly flow and warm temperatures to persist in many areas.  By late in the weekend, conditions in the Northeast became favorable for light to moderate migration to occur and persist through the remainder of the forecast period; note that some areas in the northern Appalachians realized slightly higher migration densities.  However, easterly flow in coastal areas of some portions of the Northeast prevented much more than light migration to advance into some of these locations.

Gulf Coast and Southeast

Although light to moderate migration was the norm for much of the Gulf Coast and Southeast through the week, the arrival of a strong frontal boundary early Tuesday that pushed into the Gulf of Mexico shut down movements after its passage in Texas, Louisana, and Mississippi and seems to have spawned small trans-Gulf fallouts in coastal areas.  By Wednesday night, light to moderate migration was already occurring behind the front in Texas. Despite some widely scattered precipitation, much of the Southeast exhibited light to moderate migration amounts for the duration of the period (some locally higher migration amounts did occur during the week e.g. Tuesday and Thursday images).  This includes the appearance of a wave of light migration from migrants moving between Cuba and Florida keys evident on radar in the early hours of Wednesday morning.  Note that some areas along the immediate coast in the Southeast from Florida to the Carolinas did not see much movement, probably a result of easterly flow prevailing in some of these areas.  As was the case for other regions, prevalent warm air presumably created favorable conditions for insects and aerial plankton to enter the air column, so these targets are probably mixed with birds in the radar imagery.


Predictions for arrivals of the following species were borne out. See their eBird maps by clicking on the species name:

  • In the West, as predicted,  Elf Owls arrived, Sage Sparrows made a surge, and Turkey Vultures showed signs of filling in Great Basin and northerly areas in the Interior West. Say’s Phoebes seem to be everywhere now, though the western ones clearly were on the move earlier. Are the eastern ones a mix of birds that breed on the colder Great Plains and others that head to Alaska to breed that are trickling north? Check out our other predictions too: Cassin’s and Western Kingbirds,  Bell’s Vireo Lucy’s Yellow, and  Wilson’s Warblers.
  •  In the Prairie Provinces, the predicted waterfowl arrival came in force. First arrivals for ~7 waterfowl reached Saskatchewan and Manitoba recorded a whopping 15 first-of-the-year waterfowl species.
  • On the Great Plains, a spotty vanguard of the Franklin’s Gull arrival has almost reached Canada and the American Golden-Plover is perhaps our favorite point map of the week, including one well to the east from Cape May, NJ.
  • Not an obvious migrant in all parts, due to widespread wintering, Song Sparrows have fully filled most of their range in the Northeastern US. Compare the Marchand February maps to get a sense for the change.
  • The species of the week in the Northeast has to be Eastern Phoebe. They arrived throughout the region on 18 March, and New England is showing a phoebe return that is a solid 14 days ahead of schedule. Check it out! This graph shows a frequency on 22 March (38%) that is 27% higher than the previous all-time high in eBird (in 2010); these values are about 19 days earlier than in any of the past years, except 2010 (also remarkably early for March/April migrants) which 2012 only beats by a mere 12 days!
  • Pine Warbler surged into the Northeast a couple days behind the phoebes. Theirfrequency jump from 0.6% on 19 March to 6% on 22 March, shows that they are now arrived in force, with some occurring well into New Hampshire and Maine already. Again, the New England graph is illustrative, but similar patterns show in the Great Lakes, mid-Atlantic and elsewhere. Northern Flicker reached northern areas late in the week, closer to on time.
  • Louisiana Waterthrush was a feature species in the Southeast but exceeded our expectations. Although we predicted waterthrushes “likely pushing into the mid-Atlantic,”  this map is pretty ridiculous. They are setting record early arrival date in numerous regions. This sighting from Worcester County, MD, was among the earlier mid-Atlantic arrivals just two days after our BirdCast.
  • Blue-gray Gnatcatcher and  Yellow-throated Warbler were not mentioned, but have arrived in the southeast in force too. See also advancing  Northern Rough-winged Swallows , the earliest  Prothonotary Warblers and  Yellow-throated Vireos, and drool over Southeasterners that are getting Swallow-tailed Kites now!

Overall, a pretty good score for BirdCast!

On the other hand…our White-throated Swift prediction may have jumped the gun a bit. The March 2012 White-throated Swift map shows northerly records (Colorado, California, New Mexico) from March, but most are not from the past week. It seems that the unsettled weather in the West may be causing late arrivals, unlike the remarkably early spring in the East. Predicting the future is tricky business, as we are learning!

Here are a few additional cool lists from our eBird community:

  • The mid-week prediction of a Gulf Coast fallout came to pass as predicted, a least for birders in the right places. Check out this list with 75 (!!) Hooded Warblers on 21 March.
  • The Northwesternmost Franklin’s Gull came from Wyoming on 22 March.
  • Observations of migration in action are always exciting. The Barrys have a house right on the Lake Ontario shore adjacent to Braddock Bay WMA, a renowned area for spring migration along the lakeshore. On 21 March they observed Golden-crowned Kinglets streaming from the open water of the lake into their lone Sycamore, clearly birds that had overshot during the night migration and then turned back towards land as day broke.
  • A record-early American Golden-Plover highlighted a migration watch at Cape May, NJ, on 18 May. Check out the super-cool embedded photos!
  • Lots of Ring-necked Ducks at Sanford, Maine, at least!

In addition we had a special mid-week alert about fallout conditions on the Gulf coast.

Posted 23 March 2012 by Marshall Iliff, Christopher Wood, and Brian Sullivan of the Cornell Lab of Ornithology on behalf of Team eBird and BirdCast. Special thanks to David Nicosia, our partner at NOAA, for the weather maps and analysis in our BirdCast predictions.