Conditions in the Yucatan Monday evening were obviously no good for migration. Overcast skies, 10-15 mph headwinds – no songbird in its right mind would have taken off; and even if it did, headwinds at all altitudes, stretching over the entire Gulf, would have made it change its mind pretty quick. So you could forget about birding the Gulf Coast yesterday, glorious weather notwithstanding.
Fortunately, Chazz Hesselein didn’t get wind of this forecast, and he showed up on Dauphin Island yesterday afternoon to witness a superb fallout. Hundreds or even thousands of Scarlet Tanagers foraged tamely in shrubs and on the ground; thrushes of several species allowed point-blank looks; Orchard Orioles and Indigo Buntings were present in large numbers; and as many as four Black-billed Cuckoos (a species of which most of us feel fortunate to see one) were reported across the island.
Given that anyone at all made the flight Monday night, it stands to reason that they’d be too exhausted by Tuesday to worry about snooping birders. But why would they depart at all? A headwind is a big deal, especially for smaller birds (a headwind of just 10 mph can cut down a hummingbird’s flight range – the distance its fat reserves will last – by more than half). There don’t seem to have been many warblers present on Dauphin yesterday, so there may have been a size bias among Yucatan birds willing to depart. I’m just surprised that there was a flight at all. Migrants are full of surprises.
Meanwhile, the high over the mid-South has been moving along somewhat more quickly than predicted, and we started to see the back side of it last night – allowing considerable migration on light tailwinds as far east as Jackson. Here’s the national animation: