[Bristol-Birds] Shady Valley Swainson's Warbler habitat hemlocks devastated

From: "Wallace Coffey" <jwcoffey@xxxxxxxxxx>
To: "Bristol-birds" <bristol-birds@xxxxxxxxxxxxx>
Date: Thu, 3 Jun 2010 22:01:17 -0400
I was back in Shady Valley, Johnson Co., TN, today 
for a preliminary site survey where Chris O'Bryan and I
began five years ago to photograph eastern hemlock 
trees in order to assess changes as the hemlock 
woolly-adelgid infestation was gaining momentum.

It was the same year that
 we did a survey to find
infested Steele Creek Park 
hemlocks. Park naturalists 
Kevin Elam, Chris O'Bryan 
and I found the insect 
present in an estimated 
20 percent of the trees 
surveyed along Steele 
Creek Lake on Monday, 
June 27.  It was discovered
in many of the graceful and 
beautiful hemlocks along the lake. We were pleased to 
know the park staff would get a running headstart to 
quickly treat and save the trees and preserve the scenic
beauty of the lakeshore.

Today, I wanted to visit our Swainson's Warbler sites
where John Shumate and I began monitoring this species 
and its breeding territories in Jun 1993 on Cherokee 
National Forest lands along Rt. 133 and Beaverdam Cr. 
to Backbone Rock.  By 1999, eight territories had been 
located.
Now, 10 years after those 
eight territories had been
mapped and documented, 
a study by the U.S. Forest
Service, last year,  suggests 
the insect is killing hemlocks 
in the southern Appalachians 
faster than expected. The
Swainson's Warbler is a 
"Tennessee In Need of 
Management " species and
has been found irregularly
during the breeding season 
over the state's mountain region.

All Shady locations were in wide flood plains with moist, cool 
areas which often had small pools of water.  Two additional 
territories were located at The Nature Conservancy's John R. 
Dickey Birch Branch Sanctuary just above 2600 ft.,  22 Jun 
1997, by a Bristol Bird Club mini-foray which did the first 
ever bird survey of that site.  Many of you remember taking
part in that survey since we had a large turnout of members.

Hemlocks are believed to be an important overstory species
where Swainson's Warbler habitat is prime.  A 2002 Harvard
University study found eastern hemlock has unique structural 
characteristics that provide important habitat for numerous 
bird species in the north-eastern US. As a result, removal of 
hemlock by the infestation has profound effects on avian 
communities.
It was devastating to
see the dead hemlocks
at our primary Swainson's
study site where we 
monitored the species
every year for more than
a decade. 

The loss of our hemlocks 
has been compared to past 
man-made eastern forest 
eco-disasters on the scale 
of the Chestnut blight, 
the gypsy moth infestation and 
Dutch Elm disease but little is
certain about what will happen, 
especially to our cold mountain 
streams, rivers and warbler
habitat which hemlocks benefit
with their cool shade.

 On 12 May 2010, I found two Swainson's Warblers back on our
 survey areas and one on our study site but that was well before
 the hot days of June and now the breeding season.  It will be of
 great interest to follow the species along this route on a year-to-year
 basis as the hemlocks die out.

Not enough is known about the importance of hemlock to
Swainson's Warbler breeding habitat in the Appalachians.
Surveys for nesting Swainson's conducted in the Appalachian 
mountains of northwestern South Carolina (Pickens County) 
during the breeding seasons from 1999 to 2003 were conducted
by Clemson University researchers.  A total of 74 nests were 
located, of which 60 (81%) were found in young (small) eastern 
hemlock. This nest-site selection tendency in montane populations 
had not been described. Habitat data collected in 1999 revealed 
trends of nests placed low, supported by multiple stems, close 
to the main tree stem, well concealed from above with leaf litter, 
poorly concealed from below and relatively close to streams. 
They  suggested that conservation of areas in the Southern 
Appalachians where eastern hemlock is a component of the 
forest may play an important role in Swainson's Warbler 
conservation.

Swainson's Warbler have been a fairly common summer 
resident, Apr - Jul. in Shady Valley.  It is primarily associated 
with the moist lower slopes of mountain ravines where the 
proportion of hemlock increases and rhododendron is often 
the main understory species.

Let's go birding . . . .

Wallace Coffey
Bristol, TN
[Bristol-Birds] Shady Valley Swainson's Warbler habitat hemlocks devastated

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