Forecast and Analysis

Regional Migration Analysis: 8-15 September 2017

Andrew Farnsworth The Cornell Lab Sep 15, 2017

Lincoln’s Sparrow. Peter Crosson/Macaulay Library. eBird S39143492.

Continental Summary

Moderate movements were the norm in many areas of the West this period and featured Say’s Phoebe, American Pipit, Ruby-crowned Kinglet, Townsend’s Warbler, Fox Sparrow, and Lincoln’s Sparrow, while moderate to heavy flights featuring Sharp-shinned Hawk, Merlin, Ruby-crowned Kinglet, Swainson’s Thrush, Gray-cheeked Thrush, Magnolia Warbler, Palm Warbler, and Yellow-rumped Warbler dominated the early and late days of the period in the East. Hurricane Irma brought a nasty dose of devastation to portions of the Southeast, while carrying a large array of storm-borne vagrants.

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BirdCast West Region

Upper Midwest and Northeast

Moderate to heavy flights kicked off the period, gradually decreasing to more coastal distributions by the end of the weekend. As Irma moved into the southern reaches of the region by Monday night, moderate flights continued to its north while primarily light flights occurred in closer proximity to the storm’s remnants. Note that numerous storm-displaced birds appeared in the southern reaches of the region (see this for a map). Moderate flights continued on Tuesday and Wednesday in many areas west of the Appalachians. But it was on Thursday night that moderate and locally heavy flights returned to more eastern portions of the region. Specifically, birds were aloft from the Ohio River Valley east and north into Maine, with lesser intensities close to the immediate coast.

Top Movers

Increasing

Species Increase from Last Week % of Checklists Reporting
Swainson's Thrush 298% 11.8
Palm Warbler 769% 7.6
Blackpoll Warbler 280% 9
Northern Parula 201% 9.2
Magnolia Warbler 93% 18.3
Black-throated Green Warbler 131% 11.8
Bay-breasted Warbler 173% 7.3
Northern Flicker 52% 31.1
Cape May Warbler 150% 6.4
Blue Jay 34% 63.2
Gray-cheeked Thrush 759% 2.2
Red-bellied Woodpecker 40% 32.6
Lincoln's Sparrow 969% 2
Philadelphia Vireo 200% 3.8
Common Yellowthroat 52% 25
Yellow-rumped Warbler 141% 4.6
Tennessee Warbler 79% 10.3
Black-throated Blue Warbler 139% 4.8
Nashville Warbler 84% 7
Eastern Phoebe 36% 21.4
Scarlet Tanager 92% 5.7
Sharp-shinned Hawk 148% 3.3
Merlin 101% 4.2
White-throated Sparrow 150% 2.3
Ruby-crowned Kinglet 455% 1.6

Decreasing

Species Decrease from Last Week % of Checklists Reporting
Barn Swallow -80% 4.6
Baltimore Oriole -81% 1.5
Least Sandpiper -69% 3.2
Semipalmated Sandpiper -62% 3.8
Tree Swallow -56% 6
Eastern Kingbird -73% 2
Lesser Yellowlegs -53% 4.4
Bank Swallow -96% 0.1
Semipalmated Plover -52% 4.6
Stilt Sandpiper -74% 0.8
Purple Martin -82% 0.5
Pectoral Sandpiper -59% 2.1
Spotted Sandpiper -55% 3.2
Great Crested Flycatcher -51% 3.3
Blue-gray Gnatcatcher -42% 6
Baird's Sandpiper -80% 0.4
Solitary Sandpiper -51% 2.3
Short-billed Dowitcher -69% 0.9
Buff-breasted Sandpiper -92% 0.1
Cliff Swallow -88% 0.2
Killdeer -27% 12.1
Green Heron -30% 6.9
Osprey -24% 10.8
Northern Rough-winged Swallow -57% 1.4
Olive-sided Flycatcher -61% 0.8

Brown Thrasher. Susan Young/Macaulay Library. eBird S38979075.

Gulf Coast and Southeast

Light to moderate flights occurred in many areas of the region away from Florida on Friday and Saturday nights. Irma’s arrival on Sunday and continued battering through Monday as it moved northwest shut down movements in its path. Moderate movements returned with its dissociation, with many areas of the region experiencing scattered moderate flights. The end of the period saw most of these flights occurring east of the Mississippi River Valley, with some being more intense in coastal areas.

Top Movers

Increasing

Species Increase from Last Week % of Checklists Reporting
Magnolia Warbler 879% 6.4
Common Yellowthroat 168% 8.2
American Redstart 70% 12.4
Tennessee Warbler 427% 3.1
Chestnut-sided Warbler 144% 4.8
Baltimore Oriole 139% 5.5
Brown Thrasher 51% 11.5
Swainson's Thrush 1062% 1.7
Gray Catbird 61% 8.4
Scarlet Tanager 203% 3
American Crow 24% 37.2
Eastern Phoebe 42% 13.1
Wilson's Warbler 140% 3.5
Chimney Swift 29% 16.1
Nashville Warbler 418% 1.4
Blue Jay 20% 49
Merlin 848% 0.9
Black-throated Green Warbler 116% 2.8
White-eyed Vireo 28% 18.3
Pied-billed Grebe 61% 5.3
Canada Goose 32% 10.7
Mallard 39% 8.9
Ruby-throated Hummingbird 17% 28.9

Decreasing

Species Decrease from Last Week % of Checklists Reporting
Spotted Sandpiper -46% 4.4
Purple Martin -68% 1.4
Prothonotary Warbler -88% 0.3
Green Heron -45% 6.1
Short-billed Dowitcher -71% 1.1
Least Tern -83% 0.5
Mississippi Kite -77% 0.8
Barn Swallow -30% 15.2
Eastern Kingbird -39% 4.6
Mourning Dove -19% 40.4
Gray Kingbird -84% 0.2
Blue Grosbeak -41% 3.6
Little Blue Heron -27% 9.4
White Ibis -25% 9.5
Semipalmated Plover -33% 4
Bell's Vireo -83% 0.2
Magnificent Frigatebird -104% -0.1
Solitary Sandpiper -39% 1.9
Black-bellied Plover -34% 2.7

Common Yellowthroat. Larry Therrien/Macaulay Library. eBird S39159367.

Great Plains

The region was mostly quiet on Friday and Saturday nights. Sunday saw the first pulses of moderate flights in the northern Plains, with light to moderate flights following suite in the days that followed in the central and southern Plains. Never was migration widespread across the region during the period, with more marginal conditions keeping the extent of flights more local. Locally heavy flights ended the period, though with similarly local extents in the northern and central Plains.

Top Movers

Increasing

Species Increase from Last Week % of Checklists Reporting
Ruby-crowned Kinglet 921% 6.9
Orange-crowned Warbler 362% 7.5
Yellow-rumped Warbler 432% 5.2
Lincoln's Sparrow 293% 5.8
White-crowned Sparrow -9867% 3.5
Red-breasted Nuthatch 145% 9.2
Northern Flicker 83% 25.9
Clay-colored Sparrow 167% 7.4
White-throated Sparrow 412% 3.4
Pine Siskin 169% 6
Franklin's Gull 74% 11.5
Blue Jay 34% 49.4
Sharp-shinned Hawk 421% 2.9
Vesper Sparrow 227% 4
American Robin 20% 38.5
Savannah Sparrow 189% 3.3
Osprey 115% 4.5
Belted Kingfisher 41% 12.5
Gray Catbird 37% 15.2
Eastern Bluebird 35% 17
Swainson's Thrush 91% 4.9
Horned Lark 94% 5.6
Palm Warbler 372% 1.4
Cassin's Kingbird 330% 1.7

Decreasing

Species Decrease from Last Week % of Checklists Reporting
Baltimore Oriole -96% 0.6
Great Crested Flycatcher -74% 2.4
Eastern Kingbird -69% 5
Mississippi Kite -71% 3.4
Little Blue Heron -79% 0.9
Red-eyed Vireo -57% 5.5
Black-and-white Warbler -76% 1
Chestnut-sided Warbler -92% 0.2
Bell's Vireo -76% 0.9
Cliff Swallow -72% 1.4
Bald Eagle -60% 2.5
Spotted Sandpiper -65% 1.8
Dickcissel -77% 0.9
American Redstart -55% 3.2
Eastern Wood-Pewee -47% 6.2
Olive-sided Flycatcher -56% 2.4
Barn Swallow -36% 20.7
White-faced Ibis -57% 2
American Goldfinch -30% 23.9
Magnolia Warbler -81% 0.4
Purple Martin -90% 0.2
Ruby-throated Hummingbird -34% 10.8
Least Flycatcher -45% 4.6
Black-necked Stilt -77% 0.5
Red-headed Woodpecker -35% 9.9

Lincoln’s Sparrow. DigiBirdTrek CA/Macaulay Library. eBird S39176273.

West

Light and moderate flights were the norm to begin the period. These flight increased in extent by Sunday and Monday nights, even intensifying locally in Utah and the Rockies. Tuesday and Wednesday saw these flights continue, especially in the southern Rockies and portions of the Desert Southwest. But other areas of the region were also active, albeit with lower intensity flights. By the end of the period, with precipitation becoming increasingly more widespread, migration extents became more restricted. However, intensities where migration did occur remained in the light to moderate ranges, particularly along the Pacific Coast and east along the Mexico border.

Top Movers

Increasing

Species Increase from Last Week % of Checklists Reporting
Lincoln's Sparrow 226% 6.1
White-crowned Sparrow 73% 12.8
Say's Phoebe 72% 7.5
Black Phoebe 34% 24.2
Orange-crowned Warbler 48% 12.9
Yellow-rumped Warbler 48% 10.5
Spotted Towhee 35% 17
Red-shouldered Hawk 61% 6.4
Turkey Vulture 27% 24.4
American Pipit 215% 2.7
Townsend's Warbler 82% 4.8
Western Bluebird 42% 7.9
Ruby-crowned Kinglet 99% 3.9
Savannah Sparrow 41% 9
Red-tailed Hawk 19% 19.6
Northern Flicker 16% 21.7
American Coot 25% 12.9
Fox Sparrow 129% 1.1
Northern Mockingbird 28% 8.8
Vaux's Swift 41% 3.4

Decreasing

Species,Decrease from Last Week,% of Checklists Reporting

Western Kingbird,-58%,2.6
Black-headed Grosbeak,-48%,3.1
Least Sandpiper,-35%,6.1
Western Sandpiper,-35%,5.3
Lesser Yellowlegs,-45%,2.2
Nashville Warbler,-50%,1.4
Purple Martin,-70%,0.4
Common Nighthawk,-70%,0.4
Rufous Hummingbird,-37%,3.4
Northern Rough-winged Swallow,-47%,1.4
Cliff Swallow,-49%,1.5
Barn Swallow,-19%,18.9
Black-chinned Hummingbird,-30%,4.6
Osprey,-22%,7.6
Baird’s Sandpiper,-38%,1.7
Caspian Tern,-26%,5.9
Spotted Sandpiper,-27%,4.9
Western Wood-Pewee,-26%,5.9
Ash-throated Flycatcher,-60%,0.4
Hooded Oriole,-38%,1.5
Pigeon Guillemot,-42%,1.1
Short-billed Dowitcher,-38%,1.1
Long-billed Dowitcher,-32%,2

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