Tuesday, November 7, 2017

Apparent Tree Swallow roosts in the River Parishes, visible on radar

One highlight of each November is the formation of Tree Swallow mega-roosts in the cane fields of the River Parishes.   A roost in Vaccherie has been estimated at a million birds in years past, but locations change somewhat from year to year.  I have seen them as far downstream as Luling.  They last only until the cane is cut, generally around early December.

The roosts are impressive at dusk, when huge clouds of swallows cover the sky.  Their roost entry is very strange, as the birds do not descend into the cane over a broad area, but instead "drain" from the cloud through a small funnel-shaped pathway they create.  For this reason, this phenomenon is often referred to by local birders as a "swallow tornado."

Cane fields are generally private property, so viewing options may be limited.   Sometimes a nearby river levee provides the best viewing, but sometimes engaging a farmer in conversation can open a door to driving out into the heart of the event and standing next to the funnel.  

The roosts are generally visible on the Slidell radar, when accessed online at a site that does not filter out birds.  The image below is from rap.ucar.edu, taken this morning (the 12:29 UTC on its label indicates 6:30 local time).  There are two obvious donut echos, one of which appears to be between Paincourtville and Belle Rose along (east of) Bayou Lafourche, and the other just east of Laplace, perhaps visible from Hwy 61.  Hidden between them (partially covered by the Belle Rose echo- only the southeast edge of the donut is visible) is  a third one, seemingly near Vaccherie or St. James.


Saturday, September 30, 2017

Roseate Spoonbill among waterbirds at Shrewsbury Flats

Just made a brief swing through the Shrewsbury Flats- the water retention ponds beneath Causeway Boulevard, adjacent to the Earhardt Expressway. 

An immature Roseate Spoonbill was nice, hanging with the 25 or so White Ibis and a scattering of other large waders.

The most surprising bird was a female/immature Hooded Merganser- not a species that was on my radar to turn up here.

The muddy edges are extensive, and shorebird numbers have grown to 80 Least Sandpipers, 35 Black-necked Stilts, and 4 Lesser Yellowlegs.

An adult Common Gallinule was present, which makes it easier to explain the presence of three juveniles that I saw there a few weeks back.  Looks like they nested.

Good birding,

Peter

Wednesday, August 30, 2017

Mississippi River skywatch- no tropical cyclone waifs

After leaving Holy Cross this afternoon, I took a short detour to scan the river from the levee adjacent to Tulane's Hebert Center.  Because a load of frigatebirds had come inland not far from this spot during Cindy in June, and Harvey had made landfall in approximately the same location as Cindy near the Texas border, I figured what can happen once can happen twice.

Winds were strong in my face from the (more or less) south- making whitecaps on the water and causing my pant legs to flap vigorously.   I only had binoculars, but a scope would have been useless.  The weather service reported gusts to 35 mph at nearby Alvin Calendar Field while I was there, but it sure felt more like a sustained 30-35 to me!

For the entire half hour I was there (1:40-2:10 pm) there were a dozen or so Black Vultures kiting at various heights along the shoreline to my east, evidently buoyed by winds blowing up river and deflecting up the levee there, where the river makes its sharp turn.  I kept scanning them thinking a frigatebird might be coaxed into enjoying the same updrafts (I have seen this in storm-waif frigates before), but none appeared.

An Anhinga came northwest across the river fairly high up, scarcely making any effort to do anything but let the wind carry it.  Ten on so Chimney Swifts also came across riding the gale, one seemingly on the verge of losing control as the wind bullied it forward.

Several Barn Swallows fought the wind to cross the river southward.  A buffeted Spotted Sandpiper flew by along the shore.   A handful of Laughing Gulls glided up and downstream.  One Caspian Tern flew downstream.  It was the only surprise of the visit- though only mildly unexpected.




Saturday, August 19, 2017

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


Sunday, July 23, 2017

Fall migration milestone: first Yellow Warbler reported

Although some migratory shorebirds are usually reported back weeks earlier (see my late June post), to me one of the pivotal moments of each fall migration is the first report of a Yellow Warbler.

One was reported in St. Tammany yesterday, by Jane Patterson in her back yard.

I normally expect to hear of a Yellow somewhere in the state at the very tail end of  July, but this one was a few days earlier than I anticipated.   It is the onset of a larger movement-Yellow Warbler normally seems to me the most numerous August migrant in the New Orleans area.  Because it is also one of our migrant species with the greatest propensity for "morning flight" (active migration in the early AM), it is not unusual to hear one giving its seet note overhead on any morning during the month.  I have spent many hours listening for these birds in many locations on August mornings, and have on occasion observed movements of up to 100/hour both on the lakefront and in Old Jefferson.  Most such birds appear to be westbound, and presumably are bound to circumnavigate the Gulf.  They do also stage larger corrective flights at South Point on August mornings with northeast winds, but such winds are hard to come by so early in the season, since we are generally still out of range of the cool fronts that create them.  I have long tried to figure out when during August the peak of Yellow Warbler numbers occurs; my best guess is that it is in the last few days of the month, but because substantial flights can occur earlier, I am still wondering.


Friday, June 30, 2017

First fall migrants have returned!

What?  Fall migrants?

Yes, three Lesser Yellowlegs have been reported together in the northwestern corner of the state, fresh down from their nesting grounds in Canada.

Although it seems crazy, since we are barely past the solstice and into "summer," this is actually a pretty typical time for our first fall migrants to show up.   And it is quite typically a shorebird species that leads the pack.

What happens now?  Purple Martins are at peak numbers right about now in their pre-departure roosts (including under the Causeway bridge), and will be among the first breeders to disappear.  However, things get started slowly- some martins will be around until the end of August, about the same time our Mississippi Kites vanish.  At that point fall migration as a whole will just be getting up steam.  The waves of Neotropical migrants (i.e., species that winter in the tropics in our hemisphere) will build in size  through September.  Around mid-October, movements will become dominated by species that winter in our area.   Finally, major flights will end at the close of November, with just a small variety of species with atypical migratory patterns actively migrating afterwards, such as Yellow-rumped Warblers and Cedar Waxwings. 

Changes are on the way!


Peter

Monday, June 26, 2017

Brown Booby on the Causeway Bridge


Today as I was driving southbound on the Causeway at 7:25 PM, I was treated to a Brown Booby at mile marker 16.3.  It was just off the bridge, and turned in such a way as to approach the side just as we passed.

This is the exact spot where a roost of this species has been located for the last few years.  Birders crossing the bridge had been seeing small numbers occasionally, but it wasn't until a boat trip in June 2015 that allowed better viewing of the bridge structure that we discovered that there were many more there than suspected.  The peak count I know of was of 37 on one boat visit last October.   To my knowledge, there have not been any recent boat trips- a similarly large number could still be roosting on the bridge there every day.

How crazy- this species was an extreme rarity in Louisiana waters up until a few years ago.  Then they inexplicably started appearing with greater frequency- including on near-coastal lakes and even once flying with geese over the rice country!  This tropical species has been turning up in other parts of the country- and even Canada- with increased frequency at the same time as this has been happening in our own state.  These odd appearances out of range and out of habitat together pose one of the most fascinating and enigmatic ornithological mysteries I have ever heard of, and I have yet to hear an explanation that is even remotely convincing.

So the next time you cross the Causeway, keep alert!  These birds can turn up anywhere along it, but are most likely to be seen near mile marker 16.3 on the west side.  When roosting, they are invisible from the roadway- thousands of cars pass these rare birds every day, completely unaware of their presence!

Good birding, Peter