FreeLists / bristol-birds / [Bristol-Birds] rare Great Blue Heron nest (S.F. Holston) !!

["Wallace Coffey" <jwcoffey@xxxxxxxxxx>]

A pair of Great Blue Herons have built an isolated nest on the South Fork 
Holston River in
eastern Sullivan County, TN.  To the best of my knowledge, this may be the 
region's only
nesting record for a solitary nest not in a rookery.  I saw it for the first 
time
today (Mar. 27).

The location is on the left down stream bank of the river from the Webb Bridge, 
located on
the Old Weaver Pike at what is known as Riverside.  This is not far from the 
Paddle Creek
Pond location where we have had such good waterfowl this spring.  The nest is 
about a half 
mile north of TN Rt. 44.

The nest is on an outer branch of a tall sycamore tree located on a north 
facing river cliff
and maybe 100+ feet above the river.  It is easy to spot with the naked eye.

These birds may be nesting in marginal habitat and it will be interesting to 
see if they are
successful at this location.  I am not sure how efficient they may be at 
fending against
a predator (Great Horned Owl, Raccoon and such) without the support of large 
numbers of
fellow Great Blues to help mob.  Since this species is also nocturnal, being 
away from the nest
hunting at night may expose the young to the owl.

Solitary nesting of the species is reported in literature and believed to be 
more common
in northern portions of the breeding range.
                                                                                
                   The least number of nests
I have seen at any Northeast
Tennessee or regional nest
location has been two (2).

Larry McDaniel and myself
found the first Sullivan County 
nesting and first Northeast
Tennessee nesting of the 
Great Blue Heron 10 Apr 1996
near the South Fork Holston
River just up stream of the TN Rt. 44
bridge at Central Holston.  It
had two nests with four adults
standing on the nests.  A 
storm blew one of the nests
out of the tree and the site
was quickly abandoned.

The current nesting of a single
pair on the South Fork Holston River begs the question as to whether these 
birds wintered in
the area or even along the river.  This might suggest that at least some of our 
Great Blue Herons
are "permanent residents" as individuals or pairs.  The species is recognized 
as permanent 
residents based on seasonal occurrence.  

The possibility of permanent residency for this pair might be argued on the 
basis that the 
Great Blue Heron, as with most predators, is a very solitary species except 
when migrating 
north in spring, at rookeries and during fall migration.  Some birds in the 
south are sedentary 
and do not leave the breeding ground.  The species is known to migrate north as 
a group in 
February until they establish a rookery site or return to a previous rookery 
site.  This is 
based on the very short arrival period at rookeries.  Usually one or a few 
birds come early
and then many birds arrive very shortly.

Many breeding birds from at least our area and to the south are known to 
migrate north in
late summer in what is termed post season dispersal.  This complicates the 
possibility of 
a few of our birds actually nesting and staying year around in our area.  But, 
if our region
could be considered as a forward breeding area of the southern population it 
might be that 
some of our Great Blues (at least in some years) are sedentary here year 
around.  Food
fluctuation and harsh winters might negate this in some years.  But Great Blue 
Herons have
been present on every Bristol Christmas Bird Count since 1960 (47 years) and 
average 22.6
birds/years for past 10 years and 19.1 per year for the past 20 years. 

It has been curious speculation whether birds might come together from over a 
small
region of a few counties or along certain rivers and fly in as individuals to a 
roost site.  This is 
not generally supported because they suddenly show up in late winter or early 
spring at local
rookeries and nesting behavior begins.

So the question would be why would a pair  migrate north in spring to
nest alone, away from an established rookery.  It could be argued that if two 
birds were
frequenting a mile or two stretch of river throughout the winter they might 
pair and 
simply build a nest nearby and no migration would take place. 

This single nest at Riverside was reported to me today (3/27/07) by former 
Bristol Bird Club
member Bob Cheers who has a riverside cabin near the nest.  He said residents
along the river had watched a bird break twigs and rather large branches out of 
the top of 
a tall sycamore tree in their yard and take it to build the nest.  It is known 
that the male
does this and relays the nest material to the female who places the material in 
the nest
construction.  A neighbor told Cheers one of the adults has been sitting on the 
nest for
two weeks.  Incubation may have started in mid-March.

Fascinating.

Let's go birding.....

Wallace Coffey
Bristol, TN