Sunday, September 14, 2014

South Point corrective movement this morning

This morning I made a visit to Point Aux Herbes and South Point in the Bayou Sauvage National Wildlife Refuge.  These are where the Highway 11 bridge and Twin Span leave New Orleans for Slidell, and where the railroad bridge does the same, respectively.  The former can be reached by car simply by taking the Hwy 11 Exit from I-10 shortly before crossing Lake Pontchartrain; the latter can be accessed by a 30 minute walk from the gate on the shell frontage road that runs west from the first site.

These sites are both notable for being departure points from which small land birds participating in "morning flight" head out over the water bound for the North Shore in autumn.  This happens almost exclusively under north or northeast winds, which in turn happen mostly after cold front passages.  Watching such flights is one of my favorite birding activities- a visible spectacle, revelation of the migratory urge.  They are heading northward despite it being fall- when they should be southbound.  I think the most likely interpretation of this is that they have been wind-displaced onto the coastal wetlands (and urban New Orleans) over night as they migrated, and having found themselves in hostile (for these species) terrain are now struggling to regain suitable surroundings again by heading back into the north winds that displaced them to begin with.

At any rate, this morning there was a moderate passage, of perhaps 100 birds/hour.

In 20 minutes (710-730) at Hwy 11, all crossing:  
10 Blue Grosbeak
8 Eastern Kingbird
3 unidentified warblers
3 Barn Swallows
1 Chimney Swift
1 Blue-gray Gnatcatcher

In 30 minutes at the railroad bridge (755-825), all crossing:
20 Eastern Kingbird
25 unidentified small passerine
3 Yellow Warbler
3 Dickcissel
4 probable Bobolink
8 swallows (Barn, Rough-winged among them)

In addition, a Roseate Spoonbill was flying over the marsh near the railroad bridge.  Two flocks of Blue-winged Teal (40,25) appeared to be newly arriving across the lake.


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