The enigma of species missing south of Lake Pontchartrain

Yesterday, Fox 8 posted this video of a beautiful male American Kestrel on one of their cams:

https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.facebook.com%2FFOX8NOLA%2Fvideos%2F10155849050679610%2F&data=01%7C01%7CPYAUKEY%40UNO.EDU%7C8956ab8c8d14495c605508d4e687fc01%7C31d4dbf540044469bfeedf294a9de150%7C0&sdata=TR3TwqrpUx6V%2Fct%2B%2FP5YU25l1zokjgMXo5lXqA2RbG8%3D&reserved=0


Apart from being a real looker, this bird is also of interest because it is here at a curiously early date-  the species nests on the North Shore, but is normally absent on the South Shore in the nesting season.  Being here before the normal fall migration period suggests it may have wandered down here after it finished breeding.  Such post-breeding dispersal in late summer is pretty widespread in North American birds.

But back up a bit.  Why would Kestrels nest on the north side of Lake Pontchartrain, but not the south side?  Isn't there plenty of acceptable habitat down here?  There does appear to be.  However, fully seventeen other species of North Shore nesters are also absent down here despite apparently suitable habitat:
Bobwhite
Wild Turkey
Swallow-tailed Kite
Broad-winged Hawk
Red-tailed Hawk
Belted Kingfisher
Red-headed Woodpecker
Yellow-throated Vireo
Eastern Wood-Pewee
Wood Thrush
Swainson's Warbler
Kentucky Warbler
American Redstart
Yellow-breasted Chat
Summer Tanager
Eastern Towhee
Blue Grosbeak
This used to be true of Eastern Bluebird and Northern Rough-winged Swallow as well, but they have become more regular nesters on the South Shore in recent years (or so it seems to me).  In reverse, the Bobwhite and Kentucky Warbler were more regular as nesters on the south side decades ago than they are today.

Why aren't all these species on the South Shore?  I and others have pondered this for many years, without a really plausible explanation yet emerging.  A biogeographical mystery under our noses!

Peter