4/15 IL Migration Report

Today was a fantastic day. Southerly flow continued through much of this morning, allowing for diurnal migrants to move en masse in addition to the night migrants.  All over the state, birders are reporting arrivals and influxes of BROWN THRASHERS, VESPER SPARROWS, SAVANNAH SPARROWS, CHIPPING SPARROWS, LE CONTE'S SPARROWS, WHITE-THROATED SPARROWS, SWAMPS SPARROWS, EASTERN TOWHEES, both KINGLETS, BLUE-GRAY GNATCATCHERS, YELLOW-BELLIED SAPSUCKERS, PURPLE MARTINS, BARN, BANK, NORTHERN ROUGH-WINGED, and TREE SWALLOWS, and HERMIT THRUSHES. Other arrivals/influxes include OSPREYS, FORSTER'S TERNS, SPOTTED SANDPIPERS, VIRGINIA RAIL, AMERICAN GOLDEN-PLOVERS, LAPLAND AND SMITH'S LONGSPURS, TUNDRA SWANS, and AMERICAN WHITE PELICANS.

Notice the cold front moving in the from the NW, and how it

cuts off in southern IL.

One piece of information I'm missing is any reports from the lakefront in Lake and Cook counties. It seems that throughout the state, RED-BREASTED MERGANSERS, both SCAUP, and REDHEADS remain as the most abundant overwintering ducks here, but they are declining in numbers. Most of the other ducks seem to have filed out for the most part, leaving these species and those that breed in the state. It would be interesting to see what was moving north on the lakefront, so if anyone did any lakewatches, this would be a great thing to report. As always, it is the beginning of the work week today, and thus there just aren't as many birders out there.

So how about moving forward from today? Most of the east retains yesterday's southerly flow, but a cold front has zipped in from the northwest, effectively cutting the northern half of Illinois, all of Wisconsin, Iowa, and Missouri out of the zone of favorable wind direction (See here: http://bit.ly/ZmucFO). In the north half of IL, we are now experiencing west/northwesterly winds in opposition to migratory birds...BUT...there's still hope for those in southern IL: the front is moving southeast through the center of the state right now, and bringing thunderstorms with it. The southern half of the state is still experiencing southerly winds favorable for migration, so birds will continue moving north. But when these birds come into contact with the front, migratory fallout will occur as the birds stall and are forced down by storms and unfavorable winds (the radar depicts this well; check out Illinois on the map, and see where the diffuse blue of migrating birds cuts off in southern IL). If you have a chance to check your local patch in southern IL, take it. There may be some decent influx. Higher altitude winds seem to be mostly west/southwest, so after the front passes, there may be some very light migration, consisting mostly of stronger flyers. Tomorrow, the West winds may be good for raptor and crane movement, so keep an eye out for that as well.

The east is lit up by birds, but the radar cuts off where the

cold front stalls migration in southern IL

Regardless of the conditions, like yesterday, keep an eye out for GREEN HERONS, early SORAS, CHIMNEY SWIFTS, EASTERN KINGBIRDS, BLUE-HEADED and RED-EYED VIREOS, HOUSE WRENS, OVENBIRDS, NORTHERN WATERTHRUSHES, NORTHERN PARULA, YELLOW WARBLER, maybe some Oreothlypis warblers, all the expected sparrows, and maybe some BALTIMORE ORIOLES. Early arrivals and spring overshoots could include these species, but mass influxes/passages of these birds will be happening soon if not right now.

Birds moving north in S IL at 30 to 40 knots (35-45 mph)