Favorable conditions for widespread light to moderate migration featuring Greater White-fronted Goose, Northern Shoveler, Eared Grebe, Red-tailed Hawk, Townsend’s Warbler, Yellow-rumped Warbler, and White-crowned Sparrow come to the West during the first half of the forecast period, while the East experiences several bouts of favorable migration conditions with moderate to locally very heavy flights of Pied-billed Grebe, Turkey Vulture, Franklin’s Gull, Ruby-crowned Kinglet, Gray Catbird, Ovenbird, Tennessee Warbler, Yellow-rumped Warbler, and White-throated Sparrow.
Moderate to heavy movements were the norm for the East this period, featuring Sharp-shinned Hawk, Merlin, Gray-cheeked Thrush, Swainson’s Thrush, Ruby-crownd Kinglet, Rusty Blackbird, Rose-breasted Grosbeak, Harris’s Sparrow, and Nelson’s Sparrow, while the West experienced moderate movements primarily early in the forecast period that featured Cackling Goose, Greater White-fronted Goose, Hooded Merganser, Dunlin, Herring Gull, Varied Thrush, Ruby-crowned Kinglet, Yellow-rumped Warbler, and Golden-crowned Sparrow.
Marginal and locally favorable migration conditions early in the period eventually yield to slightly more widespread favorable migration conditions, featuring Northern Shoveler, Eared Grebe, Belted Kingfisher, Orange-crowned Warbler, Townsend’s Warbler, Savannah Sparrow, and White-crowned Sparrow in the West and Bald Eagle, Chimney Swift, Northern Flicker, Merlin, Blue-headed Vireo, White-eyed Vireo, Magnolia Warbler, Pine Warbler, Common Yellowthroat, and Wilson’s Warbler in the East.
Moderate and even locally heavy flights featuring Sandhill Crane, Dunlin, Merlin, Ruby-crowned Kinglet, American Pipit, White-crowned Sparrow, and Golden-crowned Sparrow punctuated this period in the West, while moderate to heavy flights of Broad-winged Hawk, Yellow-bellied Sapsucker, Gray-cheeked Thrush, Ruby-crowned Kinglet, Magnolia Warbler, Hooded Warbler, Palm Warbler, Lincoln’s Sparrow, and Purple Finch occurred in the East following the passage of a significant cold front.
Favorable conditions for moderate movements featuring Northern Shoveler, Eared Grebe, Belted Kingfisher, Warbling Vireo, Orange-crowned Warbler, Townsend’s Warbler, Common Yellowthroat, and Savannah Sparrow highlight the beginning and end of the work week in the West, while the East experiences two pulses of moderate to heavy flights over the weekend and in the middle of the work week featuring Blue-winged Teal, Northern Flicker, Eastern Wood-Pewee, White-eyed Vireo, Blue-gray Gnatcatcher, American Redstart, and Chestnut-sided Warbler.
Moderate to heavy flights were peppered across the nation and featured Sharp-shinned Hawk, Veery, Swainson’s Thrush, Northern Parula, Orange-crowned Warbler, Mourning Warbler, Fox Sparrow, Golden-crowned Sparrow, and Dark-eyed Junco during this past forecast period, with more widespread and regional movements generally limited by a few extreme weather events in the Desert Southwest and the Atlantic Seaboard.
Marginal migration conditions begin the period, give way to more widespread flights to end the week in the West, and feature Northern Shoveler, Killdeer, Belted Kingfisher, Yellow Warbler, MacGillivray’s Warbler, Wilson’s Warbler, Savannah Sparrow, and Western Tanager, while favorable conditions kicking off the period in the East in many areas of the East, featuring Blue-winged Teal, Bald Eagle, Ruby-throated Hummingbird, Merlin, Least Flycatcher, Warbling Vireo, Red-eyed Vireo, American Redstart, Black-and-white Warbler, and Magnolia Warbler, give way to increasingly unfavorable conditions in part due to a decaying Hermine.
A busy week of migration across the nation featured light to moderate movements in the West and moderate to heavy flights in the East, with Northern Pintail, Caspian Tern, Swanson’s Thrush, Tennessee Warbler, Nashville Warbler, Magnolia Warbler, Baltimore Oriole, and Lincoln’s Sparrow on the move.
Each night, from local sunset to local sunrise in the Eastern time zone, a BirdCast server downloads radar data from 16 stations in the northeastern US. These data are composed of every scan of the atmosphere made by these radars during this time period, with a particular focus in our case on radar reflectivity products representing the magnitude of targets (whether meteorological, like rain and hail, or biological, like birds, bats, and insects) at a given radar. A pipeline of algorithms extracts information from these radar data about birds, and the resulting bird-specific summary imagery is published daily in early afternoon eastern time (give or take).
Locally favorable migration conditions increase in extent over the course of the work week in the East and feature Common Nighthawk, Ruby-throated Hummingbird, Olive-sided Flycatcher, Eastern Wood-Pewee, Great Crested Flycatcher, Prothonotary Warbler, and Northern Waterthrush, while conditions in the west remain largely marginal for migration, with locally favorable patches featuring movements of Greater Yellowlegs, Western Sandpiper, Red-necked Phalarope, Warbling Vireo, Yellow Warbler, MacGillivray’s Warbler, and Western Tanager.
As spring migration winds down, light flights featuring late shorebirds, Eastern Kingbird, Cedar Waxwing, and Grasshopper Sparrow continue in the West early and late in the period primarily in montane areas, while the last vestiges of moderate to locally heavy flights featuring late shorebirds, Yellow-billed Cuckoo, Cedar Waxwing, Sedge Wren, and Henslow’s Sparrow grace the East during the second half of the forecast period.
As the peak of migration in most areas recedes with another spring season passing, portions of the West experience light to moderate flights featuring White-throated Swift, Western Wood-Pewee, Warbling Vireo, Swanson’s Thrush, Cedar Waxwing, and Gray Catbird primarily mid and late period and patchily distributed moderate to heavy flights featuring Yellow-billed Cuckoo, Eastern Kingbird, Eastern Wood-Pewee, Cedar Waxwing, Orchard Oriole, and Bobolink occur in the East against a backdrop of a dynamic weather scene.
A period of generally favorable migration conditions featuring light to moderate flights of Common Nighthawk, Broad-tailed Hummingbird, Willow Flycatcher, Common Yellowthroat, Grasshopper Sparrow, and Western Tanager is in store for much of the West, particularly in the Rockies, while an unfavorable cool and wet start to the East gives way to later week moderate to heavy flights of White-rumped Sandpiper, Dunlin, Red-necked Phalarope, Black Tern, Black-billed Cuckoo, Red-eyed Vireo, Mourning Warbler, and Scarlet Tanager.
Light to moderate flights graced many areas from California east through the Rockies and featured Black Tern, Willow Flycatcher, Cordilleran Flycatcher, Gray Catbird, and Bobolink, while pulses of moderate and heavy flights featuring White-rumped Sandpiper, Common Nighthawk, Black-billed Cuckoo, Alder Flycatcher, Bay-breasted Warbler, and Canada Warbler were scattered across the East.
IMPORTANT NOTE: Team Birdcast is focusing on preparing for tomorrow’s Global Big Day, and as a result we haven’t been able to write a thorough forecast and analysis by our usual Friday deadline. Here is an abbreviated forecast, with weather maps and species lists; the analysis for the past week and potentially a supplemental forecast […]
Migration conditions will be generally more favorable across southern half of the West this week where moderate flights will feature Wilson’s Phalarope, Red-necked Phalarope, Black Tern, Willow Flycatcher, Yellow Warbler, MacGillivray’s Warbler, and Green-tailed Towhee, while midweek in the East will see the most extensive moderate to heavy flights of Black-crowned Night-Heron, Semipalmated Plover, Short-billed Dowitcher, Black Skimmer, Common Nighthawk, Black-billed Cuckoo, Acadian Flycatcher, Eastern Wood-Pewee, Canada Warbler, Blackpoll Warbler, and American Redstart in a pulse of significantly warmer air.
Moderate movements, particularly from California east through the central and southern Rockies, featured Black Tern, Cordilleran Flycatcher, Plumbeous Vireo, Swainson’s Thrush, Black-headed Grosbeak, and Western Tanager and highlighted the period in the West, while moderate to heavy flights, particularly in the central and southern US, featured Common Nighthawk, Yellow-bellied Flycatcher, Least Flycatcher, Philadelphia Vireo, Veery, Magnolia Warbler, and American Redstart and highlighted the period in the East.
When birders in Cape May awoke on Monday morning, an interesting pattern was emerging (interesting is the norm in Cape May!). Numerous observers reported that numbers of migrants had arrived during and after the night and were still coming ashore from the Atlantic Ocean. The first real pulse of arrivals of this spring for a number of species had clearly occurred in Cape May. The combination of on the ground reports from eBird, nightly northeastern US radar data processing with BirdCast algorithms, and the excitement of spring arrivals inspired Team BirdCast to look a bit more closely at the events leading up to this movement.
Favorable migration conditions in the latter half of the period for the West will bring extensive light to moderate movements of Spotted Sandpiper, Olive-sided Flycatcher, Dusky Flycatcher, Warbling Vireo, MacGillivray’ Warbler, Lark Bunting, Clay-colored Sparrow, and Chipping Sparrow, while a highly variable period for weather in the East will bring similarly variable and patchily distributed moderate to heavy movements featuring Least Sandpiper, Forster’s Tern, Olive-sided Flycatcher, Least Flycatcher, Acadian Flycatcher, Wood Thrush, Swainson’s Thrush, Golden-winged Warbler, Nashville Warbler, Cape May Warbler, Blackburnian Warbler, and Baltimore Oriole.
Light to moderate flights, primarily in the Desert Southwest and the eastern Rockies, were the highlights of the week in the West and featured Wilson’s Phalarope, Vaux’s Swift, Western Wood-Pewee, Hammond’s Flycatcher, Brown-crested Flycatcher, Warbling Vireo, Yellow Warbler, Hermit Warbler, Summer Tanager, Western Tanager, and Lark Sparrow, while moderate to heavy flights featuring Mississippi Kite, Willet, Ruby-throated Hummingbird, Western Kingbird, Gray Catbird, Bay-breasted Warbler, Black-throated Blue Warbler, Rose-breasted Grosbeak, Blue Grosbeak, Dickcissel, and Baltimore Oriole were extensive in many areas of the East.