Swallow tornado

Tonight I tried to track down a Tree Swallow roost that has appeared to be visible on radar on the West Bank near the St. John/St. Charles parish line.

These annual November roosts are one of the great wildlife spectacles of Louisiana, with hundreds of thousands of swallows gathering in a massive flock before descending into the cane in the gathering dusk.   The roost entry is in the form of a strange tornado-like funnel (made of birds) that extends from the swallow cloud down into the cane.  The birds "drain" through it as darkness falls.

I had never visited this site before, but located it on radar- an expanding donut ring (or one side of a donut) visible at dawn on rap.ucar.edu, a site that does not filter out bird echos.  When I arrived tonight I found birds streaming over the fields toward the river, and so I followed them and climbed up on the levee to find hundreds drinking (or catching bugs?) on the surface of a pond in the batture.  Large numbers seemed to be gathering higher in the air upstream from there, so I drove a ways in that direction on the River Rd.  I ended up going too far, passing the birds, but could see 100,000 (very rough estimate) high up in the air with binoculars (beyond unaided vision) back in the direction from whence I had come (see photo below).  A falcon of some sort was now maneuvering within the flock, very high in the air, but I could not afford the time to try to identify it to species. 

I returned a bit downstream and could not relocate the flock (how can it be hard to relocate that many birds?!?), until I saw their entry funnel coming down out of the then fairly dark sky a bit farther back downstream toward their drinking pond, blocked from view somewhat by a woodlot.   I moved farther downstream to get closer and saw the last minute or so of the roost entry, the final pulse of birds swirling down through the "funnel" into the cane.  It was surprising how short a time it took for the whole entry to be completed for so many birds.

A local resident came out and couldn't stop talking about how she and her husband had watched these birds in awe for the last couple of weeks and wondered who she should call to report them to.  Blackened the sky, she said.  I told her the roost in Vacherie had been reported at a million in years past and she said she thought that was a low estimate for what she had been seeing.

She said that earlier in the month the birds were streaming overhead toward cane fields upstream at dusk, and only in the last couple weeks had relocated to the cane just off the end of her street.  The street is private, so viewing might only be from the river levee across from it around 350 yards away.  I am not sure the attitude of the St. Charles Parish levee board toward people being up on the levee.

The exact coordinates of tonight's funnel entry point are 30 deg 1 min 10.5 sec N, 90 deg 29 min 48.2 sec W.  This is in the town of Killona.

I managed to snap one picture of the gathering flock, from a great distance (still beyond naked eye detection), posted below.  I felt there were probably 100,000 in an initial count (the picture only includes a part of it), but it seemed it grew afterwards- maybe several fold- but I would hesitate to hazard a guess until I get more optimal viewing conditions.  Unfortunately, this roost location will probably only persist till the cane is cut, which is ongoing.

Peter