[Bristol-Birds] absence of Cliff Swallows in much of North Fork Holston area.

I am beginning to wonder if there is a fundamental bridge 
structure design difference used by the Virginia Department 
of Transportation than that used by the Tennessee Department 
of Transportation.  

A significant number of bridges in NET have Cliff Swallow colonies.  
That is almost non existent in SWVA.

I went birding west of Bristol Virginia in Washington Co. today (5/26),
well before the rain.  This area is mostly in the North Fork Holston
River watershed.

One objective was to check bridges over the North Fork Holston River
for nesting colonies of Cliff Swallows.  Nothing found !  Did not even
see the species.  Cliff Swallows along the North Fork have been a
really tough nut to crack.  Why so ?  This is a fairly rare and much more 
local summer visitor/resident in the southern portion of the Mountains 
and Valleys region of Virginia.  It is a much more common bird in
Northeast Tennessee, even in the upper Holston watershed counties.

Two target bridges checked today where the Phillips Bridge over the
river at Rt. 615 at the edge of the village of Mendota. A second target 
was the Rt. 622 bridge on Nordyke Rd. which is 7.4 river miles up stream.  

The large I-beams which hold the bridges and extend their length on 
either side are not suitable because of the way the swallow hangs its 
gourd-shaped nest.  I found no indication of old nests or even mud where 
nesting attempts have been made.

As early as early as 11 June 1966, Coffey and Dr. J.J. Murray of the
VSO, found a pair of nests under the old U.S. 19 bridge over the North
Fork (1525 ft. elevation) just west of Abingdon.  Several other birders
saw the nest the next day since that was part of the VSO-sponsored
Abingdon Foray.  That bridge has been rebuilt or altered in recent
years.

In Southwest Virginia, Roger Clapp of the U.S. National Museum,
had seven nest 20 June 1989 under the bridge over Fifteenmile
Creek at the junction of Va. Rts 676 & 672  3 miles north of 
Avens Bridge which is on South Holston Lake in Washington Co., VA.
It was a good ways from South Holston Lake and the river channel. 


15 May 2005, while birding at South Holston Lake,  I counted 201 
nests of the Cliff Swallows under Avens Bridge in Washington County, 
VA.  This made that colony one of the largest in the state and the
largest in Southwest Virginia.

There is much to be learned about the how and why of Cliff Swallow
nesting dynamics in Southwest Virginia.

Let's go birding . . . .

Wallace Coffey
Bristol, TN

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