Tuesday, August 13, 2013
Fall migration preview- what to expect
We are now in mid-August, and the fall migration is beginning to gain momentum. Here is what to expect, and what to watch out for in the realm of land birds.
In August the most conspicuous migrant is Yellow Warbler, which is far more in evidence now than in any other month. They are especially fond of willows and tall ragweed thickets. Listen for their sharp, sweet chip note. By month's end, Purple Martins and Mississippi Kites will be almost entirely gone from our skies.
The next migrant to become especially conspicuous will be Eastern Kingbird, which peaks in numbers in a narrow window around the first week of September. These birds often occur in flocks, on the move in daylight in relatively open environments- often right through residential neighborhoods. Keep your eyes on the sky.
Early September begins the flood of species coming through headed for the tropics. Although a few have already reached peak numbers in August, such as Orchard Orioles and Ruby-throated Hummingbirds, most will peak this month- including most warblers. Most male warblers lack their striking spring dress, but some look essentially the same as in spring- such as Black-and-White and Hooded. From mid-September to mid-October is the best time of the entire year for finding American Redstart, Magnolia Warbler, Common Yellowthroat, and Northern Watherthrush- four of the most common warblers this time of year. The same is true of Eastern Wood-Pewee, which takes up territories in fall migration and can often be heard making short whistles and hefty chip notes from an open branch. Summer and Scarlet Tanagers and Rose-breasted Grosbeaks are also frequently seen. Male Scarlets are now greenish, but male Summers are still bright red. All of these turn up in urban yards with shade trees and (ideally) some understory. City Park (Couturie Forest) and Audubon Park (along the bayou, or the west side, and in the live oaks everywhere) are also good places to look.
The last prominent tropic-bound migrants to peak are Gray Catbird and Indigo Bunting, in mid October. Both bunting sexes are in their subtle brown winter garb. The ragweed thickets that teemed with Yellow Warblers in August will be taken over by this species, often in flocks. Often a few Blue Grosbeaks are mixed in (their males stay blue).Catbirds are in these thickets, and also in wooded understory. They are often revealed by their cat-like mew.
As the Indigos are peaking, the first of the waves of species that will winter here begin to arrive. Eastern Phoebes often put on a show, fussing at each other as they establish winter territories. They are in open marsh, field, and edge habitats outside the city, and in some open areas within it as well. Swamp Sparrows arrive and settle into the marshes, but often turn up in the ragweed thickets or even any empty weedy urban lot (often with Common Yellowthroat and sometimes Marsh Wren) when they first arrive. These same weedy areas will attract other sparrows in late October and November.
Yellow-rumped Warblers build in numbers through November, accompanied by smaller numbers of Ruby-crowned Kinglets and Orange-crowned Warblers. These species will spend the winter, but are often more numerous in November than later. This may also be the best time to see Yellow-bellied Sapsuckers in our urban neighborhoods, since they also carry on vocally and with chase as they set up their winter territories.
Migrants are around more consistently from day to day in New Orleans in fall than in spring, when they have a more severely weather-dependent boom and bust pattern. Nevertheless, the first morning after a cold front passage is often the time when the most migrants are around; these increase in frequency as the fall progresses and the jet stream shifts closer to us.
Its going to be a fun next few months!
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