Monday, April 21, 2014

Migration Forecast: April 22 - 26

A Yellow-rumped Warbler helpfully shows off its namesake field mark - as well as the yellow crown spot responsible for the second part of its scientific name, Setophaga coronata
Monday, April 21, 2014: Although last night's radar picture showed a lot of movement to the south of us, today there were only modest numbers of migrants at stopover habitats along Lake Erie. Southerly winds during the night were not as strong or consistent as had been predicted, and no big concentrations of migrants piled up along the immediate lake shore. 

Looking ahead, conditions don't look good for bringing in major numbers during the next couple of days. But a low-pressure system is approaching from the west, and at some point on Thursday, April 24, we should have a low-pressure center to the west and a mild high-pressure center to the east, setting up a strong northward air flow all the way from the Gulf of Mexico - and in conjunction with that, a warm front should pass through. These conditions would be ideal for bringing in a major wave of migrants. 

The timing of this is still uncertain, with some disagreement among weather forecasts. If the winds turn southerly as early as Wednesday night, we could see a lot of new migrants on Thursday morning. But based on most forecasts, I expect the southerly winds to arrive Thursday, followed by the warm front later in the day, and for southerly winds to persist through Thursday night and much of Friday. 

If the timing works out that way, Friday the 25th could see the next real push of migrants. If so, that would be classic timing. Looking at results from BSBO's long-term banding research, Mark Shieldcastle has found that the average date for the "first wave" of migrants is around April 24-25. 

Currently the dominant migrants in the woods are Yellow-rumped Warbler, Blue-gray Gnatcatcher, Ruby-crowned Kinglet, and Hermit Thrush, with lesser numbers of Eastern Towhee, Yellow-bellied Sapsucker, Blue-headed Vireo, Winter Wren, White-throated Sparrow, and others. Warblers present in small numbers include Pine, Palm, Black-and-white, Black-throated Green, Prothonotary, and Northern Parula. Numbers of most of these should pick up when the next wave arrives, along with Nashville Warbler and a scattering of additional species. 

To summarize, based on current weather forecasts: modest numbers of migrants continuing for the next couple of days, Tuesday and Wednesday, April 22-23; wind shift on Thursday, April 24, may bring some daytime migration (hawks and others) along the lakeshore; Thursday night may produce a migratory movement, making Friday, April 25, a good day (or possibly a very good day) for new arrivals. If many birds arrive on Friday, shifting winds should keep most of them around through the weekend, April 26 and 27. Of course the weather forecast can change, so I may be updating this. But at the moment, Friday April 25 looks like the best day in the next week. 


Anonymous said...

I find your information very helpful please keep up the good work.

Beaks Wings and Backyard Things said...

We have been looking forward to your updates on the blog! We love following you and would like to thank you and Kim for all of the work you do. Thanks for keeping us informed.

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