Forecast and Analysis

Migration Forecast: 24 – 30 March 2012

Andrew Farnsworth The Cornell Lab Mar 24, 2012

We expect the pace of record-early spring arrivals from throughout the eastern two-thirds of the country to slow significantly this week. While a few birds may continue to push north, don’t expect the massive movements of birds from the last two weeks as unsettled conditions will likely predominate across much of the continent. Temperatures are still forecast to be warmer than usual, but winds will be generally poor for migration. There is certainly potential for locally excellent birding conditions if you can find a place where southerly winds meet rainy conditions which may produce localized fallouts of early season migrants.

While migration is likely to be slowed this week, watch for Blue-gray Gnatcatchers which may arrive early in some locales

While migration is likely to be slowed this week, watch for Blue-gray Gnatcatchers which may arrive early in some locales

A Note of Caution

While we are in the midst of one of the earliest springs on record for much of the US and Canada, but it is not affecting all species equally. In order to better understand which species are responding to this warm spring and which ones are not, we need to continue to be rigorous in our data quality standards, which give eBird data credibility and make the data useful for scientific analysis. Check the bar charts for your county or state to determine when species typically return and please document sightings from outside the normal arrival period. Photo documentation is ideal (if it can be obtained). eBird data are increasingly being used to study a variety of large scale questions and we have encouraged our regional editors to take a conservative approach for records that fall significantly outside the normal periods of arrival. Providing strong documentation is the best way to make sure your early records are taken seriously. Note that even if your record is not accepted by regional reviewers, it is never deleted and still shows up in all of your personal records, but are considered unconfirmed in eBird’s public data. Please also be aware, that while many species are arriving early, this does not mean that late migrants like Willow Flycatcher and Black-billed Cuckoo will be next in line. See the Ruby-throated Hummingbird text under the “Upper Midwest and Northeast” below for one cautionary tale.

Forecast for 24 March 2012.

Forecast for 24 March 2012.

Daily forecast maps from NOAA with an overall summary are available here.

Links to species names below take you to the March eBird maps for 2012.

Blue-gray Gnatcatcher

Already on the move, the first Blue-gray Gnatcatchers have been detected as far north as the mid-Atlantic this week, including a notably early bird on this checklist from Prince George’s County, Maryland. While early for the big push, gnatcatchers may become widespread this week at southern and mid-latitudes. New England and Great Lakes observers should keenly search for their first of the year sightings and may set all-time record arrivals. Some of these may be birds that have already arrived and may be more detectable as chillier conditions could force birds to warmer areas along rivers and near wetlands. When watching gnatcatchers, pay particular attention to vocalizations, which differ between Western and Eastern populations. See Nathan Pieplow’s excellent discussion of vocal differences in his article on the blog. eBird does allow you to report your Blue-gray Gnatcatchers at the subspecies level, and your eBird records can help to define the edges of the ranges of the two forms, but please only do so if you feel well-versed in identifying these to subspecies!

Regional Forecasts


Beginning early in the forecast period, favorable conditions will facilitate light migration in the desert Southwest, and these favorable conditions will likely continue through the week. Moreover, as the week continues these conditions are forecast to expand to a broader region including the Central Valley of California, the Four Corners area, and north into the Great Basin and Rockies up to the Canadian border, suggesting that light migration may be more widespread in these areas than in recent weeks. With the onset of another round of storms, the Pacific Northwest will continue to see generally poor conditions for migration; however, early in the forecast period, some light migration will be possible.

  • Watch for an influx in the number of grebes in the Interior West including Horned,EaredWestern and Clark’s.
  • Expect a continued arrival of vireos in the West. Note how much earlier the southwestern populations of Bell’s Vireo arrive compared to those in the East.  The same is also true for Warbling Vireo, which should continue to appear in good numbers in California.
  • A number of songbirds arrive much earlier in California than in other portions of their range. Hooded and Bullock’s Orioles are two colorful ones to watch for as they fill in their breeding range west of the Sierra Nevada this week, well before their arrival in points east, like Arizona. In California, Hooded Orioles are palm specialists, so can be regularly seen in residential areas where planted palms are common. See if you can find one this week.
  • Swallows will continue to increase with good numbers of Northern Rough-winged,Cliff and Barn Swallows in the southwest and extending up the coast. The first few individuals may appear farther inland — watch for them particularly during inclement weather when large numbers of swallows may gather at lakes and wetlands.
  • We expect fair movements of raptors including small numbers of Cooper’s and Sharp-shinned Hawks. The first Swainson’s Hawks are already appearing from California though New Mexico and by the first of April, should reach Colorado and Utah in fair numbers.

Great Plains

Light migration will be possible in light forecast winds at the beginning of the weekend, though it is not likely to be extensive given the cooler temperatures and less favorable wind conditions. By Sunday, western Plains states should see light movements, expanding farther to the east and south as the week progresses.  Toward the middle of the week, the potential for precipitation and variable winds may shut down most movements, with only scattered light movements apparent. By the end of the forecast period, any migration will likely be in the northern Plains states, where light migration should occur.

  • Both species of kinglets should be on the move this week in the Great Plains and beyond. Ruby-crowned Kinglet numbers will build in Kansas and Oklahoma. Ruby-crowned is currently unreported during March in eBird from the North Dakota and has only one record from South Dakota. While weather conditions are no longer optimal, this may be one of the best years for a March record and for early arrivals elsewhere. There were not large numbers of Golden-crowned Kinglets wintering in the southern Great Plains this year, but some migrants should be found throughout this region this week, perhaps into Saskatchewan.
  • While Vesper Sparrows winter in portions of the southern Great Plains, expect influxes into Kansas and Colorado with scattered individuals farther north into Nebraska. This is another species that hasn’t yet been recorded in eBird in the Dakotas, but this species could be found this week (if effort is made to find it!). Vespers are sometimes found in very large numbers under optimal conditions (when southerly winds hit rain, snow or other precipitation), so there could be localized high counts this week.
  • Continue to watch for swallows, with increasing number of Tree Swallows in Kansas, Oklahoma and Nebraska. We still expect them to show up in North Dakota and South Dakota. Will there be enough coverage to find one? The firstBarn Swallows and Northern Rough-winged Swallows should arrive in Kansas and perhaps farther north.
  • While not migrants, we would be remiss in not highlighting some of the most fabulous displays of early spring: the marvelous courtship displays of Greater Prairie-ChickenLesser Prairie-Chicken and Sharp-tailed Grouse. While males can often be found on leks into June, displays and activity are at the peak from mid-March through mid-April. Looking at the eBird bar charts would suggest these birds are migrants. While many grouse do make short movements, the differences here are a result of changes in detectability, as well as strong biases as to when birders go seeking these prairie performers.
  • Watch for movements of American Golden-Plover and Smith’s Longspur to continue from Kansas to Indiana.

Upper Midwest and Northeast

With the northerly flow in the Upper Midwest and Northeast for much of the week, the fast-paced migration to date is likely to slow substantially, and new arrivals will be comparatively few in the coming week. It may be that a few more birds trickle in, but the next significant push of migrants is not likely until the next blast of warm southern air, which may not happen until after 30 March. One interesting thing to watch for will be whether species like Blue-gray Gnatcatcher and Louisiana Waterthrush continue to push northwards despite the less than perfect conditions. Even in inclement weather, the urge to migrate could drive a continued northward march. These two species have arrived very early back on territory as far north as New Jersey, Tennessee, and Missouri (southern Illinois, southern Indiana, Pennsylvania, and New Jersey for the waterthrush), so we’ll be watching this week to see if they advance even farther north.

  • With some rain forecast for the coming week, watch for concentrations of swallows. We know that thousands of Tree Swallows are back in the north, but are probably spread widely across the landscape. Cooler weather and rain could concentrate them over ponds, and in these situations be sure to watch for other early swallows like Barn, Northern Rough-winged, or Purple Martin.
  • Some waterbirds are stronger fliers and are due to arrive this week regardless of the weather. Watch for Double-crested Cormorant to push into their Northeastern nesting areas and for herons and egrets to arrive back in saltmarshes as far north as Maine. Forster’s Terns and Laughing Gulls will continue to move northward along the coast too.
  • The first migrant Eastern Willets, the coastal saltmarsh nesting form that winters in South America, might reach the mid-Atlantic late this week. We are still learning what route they take to get here. Is it, at least partly, directly over the ocean from the eastern Caribbean islands?
  • Watch for many wintering waterfowl to get significantly scarcer in their wintering areas this week as they continue to move northward. Are they leaving early in this warm year? It certainly seems that Common MergansersCommon Goldeneyes, and Snow Geese in the mid-Atlantic (where they generally don’t nest) have vacated the area earlier than normal.
  • Even mid-Atlantic American Tree Sparrows seem to be leaving early, hitting a five-year low for late March, with the next lowest year also being the next warmest (2010). Watch for the last birds in the mid-Atlantic this week and an early departure in the couple weeks from New England and the Upper Midwest.
  • There have been some internet reports of Ruby-throated Hummingbirds returning as early as mid-March to points as far north as New England, northern New York, Michigan, and Wisconsin. Since eBird is detecting no such movement this early, and since no corroborating documentation has been provided for these early reports, these reports could be typographical errors or even misidentified bumblebees. We do encourage eBirders to carefully note their hummingbird arrival dates and provide documentation when they find the first one in their region, so that eBird can provide useful, scientifically-defensible data on the return of hummingbirds in this exceptionally warm year. Better yet, try putting your feeders out early and see if you can help prove that hummingbirds DO move early!

Gulf Coast and Southeast

Early in the weekend, areas of Texas, Florida and the Southeast coast will experience light to moderate migration, especially in areas where winds are southwesterly. In the Southeast and Florida, watch migrant traps along the immediate coast for evidence of new arrivals. Additionally, there is potential for a small Caribbean influenced trans-Gulf migrant fallout from the panhandle of Florida and perhaps in portions of the Southeast depending on the distribution of rain during exodus of migrants from the Caribbean and upon arrival in the US. Sunday and Monday will see more prevalent northerly and westerly wind flow and precipitation may shut down movements in many areas, although moderate migration (trans-Gulf and circum-Gulf) may occur along the southern Texas coast with some local fallouts given potential precipitation meeting favorable winds for migration. By Tuesday the likelihood of trans-Gulf flights increase farther to the east along the Gulf coast, and by week’s end, Florida and the Southeast may see light to moderate migration along the Atlantic coast as southwesterly winds push birds into these areas. Good conditions for sea-watching could occur along the east coast of Florida on Tuesday. The Florida Keys should see mid- to late week inputs of migrants, and by Friday there is potential for fallout in the Keys if forecast precipitation intersects southerly winds.

  • While many waterfowl have departed the region, numbers of Fulvous Whistling-Ducks are on the rise as they return northward. Expect a continued influx this week in Texas and Louisiana, mostly near the coast. Look for this species flying just offshore, at times with flocks of Blue-winged Teal (a species whose numbers are increasing throughout much of North America).
  • Watch for increasing diversity of wood-warblers throughout the Southeast.  Black-and-white Warbler and Northern Parula should be widespread throughout the region. Prairie Warblers will be common in much of Florida with some pushing into the Carolinas; Mid-Atlantic observers might have their best chance ever to get a record-early one in March and should actively check for them towards the end of  the week. The arrival of Worm-eating Warbler will likely be more confined to the Gulf Coast states.
  • Watch for the first push of Upland Sandpipers this week. Most are likely to be found in Texas but small numbers could also be seen in Louisiana and perhaps into the southern Great Plains. They are best looked for on sod farms, short grassy fields, or detected by their bubbling call either in flight or when perched.

Posted 23 March 2012 by Christopher Wood, Andrew Farnsworth, Marshall Iliff, and Brian Sullivan of the Cornell Lab of Ornithology and David Nicosia of NOAA, on behalf of Team eBird and BirdCast.