Northern Saw Whet Owl Trapping During Autumn 2008 at

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					Northern Saw-whet Owl Trapping During Autumn 2008 at Big Bald Banding
Station, Cherokee National Forest, Unicoi County, Tennessee

2008 Annual Report to United States Forest Service, Cherokee National Forest

Mark E. Hopey, Southern Appalachian Raptor Research, PO Box 305, Mars Hill, NC 28754
Kathryn A. Gunther, Southern Appalachian Raptor Research, PO Box 1903, Anacortes, WA



Introduction

The 2008 season is the fourth autumn that systematic Northern Saw-whet Owl trapping
has been conducted at Big Bald Banding Station (BBBS). Formal data regarding
migrating passerines using the Big Bald Mountain environment have been collected at
generally the same banding site since 1978. BBBS bands approximately 2000 passerines
every autumn of some 50 species. A limited raptor trapping station was begun in 2003 to
better sample the migrating birds of prey observed on the ridge in conjunction with the
peak of passerine migration. The raptor trap station was fully staffed in 2004 and has
operated each autumn, annually luring and banding approximately 100 birds of prey of 10
different species. The Big Bald Hawk Watch also commenced in 2003, documenting the
passage of 15 different species of raptors annually. From 2003-2008, Big Bald Hawk
Watch has counted a total of 12,644 birds of prey, averaging 2107 migrating raptors each
season.

Northern Saw-whet Owl (NSWO) has been documented at Big Bald through aural
surveys since 2000 and incidental diurnal capture in passerine mist nets since the autumn
of 2003. Big Bald Banding Station conducted nocturnal trapping a minimum of six times
per season starting in 2005. Data gathered by banding NSWO in 2005 led the Cherokee
National Forest to install man-made owl nest boxes on the northern flanks of Big Bald
Mountain.

Location

Big Bald Banding Station (BBBS) is located high on Little Bald Mountain at 5390 feet
above sea level (1643 m), inside the Appalachian Trail corridor in Cherokee National
Forest, Unicoi County, Tennessee. The habitat is an edge transition mix of grassy bald,
invasive annual and perennial shrubs, stunted northern hardwoods, a few scattered
immature spruce-fir trees and native heath shrub thickets. Wide vistas open to the north
towards Erwin, TN and northeast toward Roan Mountain. Mt. Mitchell and the Black
mountain range, with the highest peaks in the eastern U.S., loom ten miles to the
southeast.

Methods

Trapping of NSWO was conducted during appropriate weather windows from sundown
to a variable end time during the night. The BBBS passerine banding station, consisting
of 16 mist nets in permanent locations, was used as traps for migrating owls at night. All
trapping was done following protocols established by the US Bird Banding Lab, North
American Banding Council, and Project Owlnet. Project Owlnet is a national program
designed to improve the knowledge of the migration of NSWO by promoting the
establishment of a network of owl banding stations across the continent.
Playback calls of the NSWO were broadcast as audio lures using a ‘boom box’ with Mp3
recordings as suggested by the Project Owlnet web site. Captured owls were processed in
the accepted manner for small raptors with aging established through flight feather
observations (Pyle, 1997) and more recent information from the Owlnet webpage. Sex
was determined using the wing-mass data chart developed by David F. Brinker available
from Project Owlnet.

Results

Trapping for Northern Saw-whet Owls was attempted on 7 nights at Big Bald Banding
Station beginning in late September and continuing into early November, 2008
(Table 1). A total of 18 owls were captured during 221 net hours of effort. Fourteen
NSWO were new captures, two owls were recaptured twice and two were return captures
banded in past years. Eleven of the 14 new captures were aged as hatch year and three
owls were determined to be after hatch year. The gender of eight hatch year birds was
evenly split. The sex of three hatch year owls was not determined. Of the three new after
hatch year owls captured, one was male, one female and one was of undetermined
gender.


Table 1. Trapping dates, effort, age and sex results for Northern Saw-whet Owls
trapped during autumn 2008. Big Bald Banding Station, Cherokee National Forest,
Unicoi County, Tennessee.

MONTH        DATE      OPEN      CLOSE      NETS      NET      NEW        F    M      M       UKHY      RE       RE
                                                      HRS     NSWO       HY    HY    AHY                CAP     TURN
  SEP          18      2000       2250       15       37.5       1              1
  SEP          23      2100       2200       15        15        0
  OCT           4      2150       2250       15        15        3       2                      1                 1
  OCT          15      2000       2350       15       52.5       5       1      2               2        2        1
  OCT          19      1950       2200       15       37.5       1                              1
  NOV           1      1850       2100       15       37.5       3       1      1               1
  NOV           5      1950       2150       13        26        1                     1

TOTALS                                                221       14       4      4      1        5        2        2
HY=hatch year, AHY=after hatch year, i.e. adult of undetermined years, SY=second year, M=male, F=female, U=undetermined


Two owls were recaptured during the seven trapping sessions, banded during the
previous week at Big Bald. Two owls trapped were ‘returns’ from the 2007 banding
season (Table 2). One second year female bird recaptured as a ‘return’ on October 4th
was originally banded at Big Bald on September 16th, 2007 as a hatch year bird. The
second ‘return’ was a second year male owl recaptured on October 15th and originally
banded on October 29th, 2007 at Big Bald. Both ‘return’ birds were in good health with
no signs of distress or problems associated with their leg bands.
Table 2. Descriptive banding measurements of Northern Saw-whet Owls, autumn
2008. Big Bald Banding Station, Cherokee National Forest, Unicoi County, TN.

BIRD     MONTH      DATE       SPP      AGE     SEX      WT     TAIL   HAL     WING     CUL       TRAP         STATUS
  #                                                                                               TIME
  1       SEPT        18     NSWO        H       M       83      70     7.7     128     12.5      2213
  2       OCT         04     NSWO        H       F       89      66     8.2     137     11.8      2245
  3       OCT         04     NSWO        SY      F       94      69     8.9     140     12.9      2300         RETURN
  4       OCT         04     NSWO        H       U       84      65     8       132     10.8      2310
  5       OCT         04     NSWO        H       F       93      78     9.2     146     13.5      2315
  6       OCT         15     NSWO        SY      M       79      60     7.8     133     12.2      2046         RETURN
  7       OCT         15     NSWO        A       F       89      62     8.5     134     12.9      2120
  8       OCT         15     NSWO        H       M       72      68     8.5     133     10.8      2145
  9       OCT         15     NSWO        H       U       88      65     7.7     130     11.6      2155         RECAP
 10       OCT         15     NSWO        H       U       86      72     8.4     139     12.2      2245
 11       OCT         15     NSWO        H       F       94      77     9.6     144     12.6      2250         RECAP
 12       OCT         15     NSWO        H       F       93      76     8.7     144     11.8      2300
 13       OCT         15     NSWO        H       M       75      66     7.7     130     12.3      2306
 14       OCT         19     NSWO        H       U       87      67     8.5     137        13     2100
 15       NOV         01     NSWO        H       M       74      72     7.7     134     12.5      1945
 16       NOV         01     NSWO        A       U       86      65     8       139        12     2040
 17       NOV         01     NSWO        H       F       91      57     7.7     136     13.7      2100
 18       NOV         05     NSWO        A       M       77      72     7.8     132     12.6      2030




Discussion

This is the fourth consecutive autumn that systematic owl trapping has been conducted at
the Big Bald Banding Station with a total of 57 NSWO banded (Table 3). Data collected
at Big Bald increasingly points to the possibility of resident NSWO nesting in the
immediate area.

Nest boxes placed on the northern flanks of Little Bald in 2006, approximately 0.2 km
from the Big Bald Banding Station, were periodically checked during the breeding
seasons for NSWO use. One box during the 2008 season held NSWO eggs that were
depredated by an unknown predator (USFS personal communication).

Table 3. Age and Gender of Northern Saw-whet Owl trapped at Big Bald
Banding Station, Cherokee National Forest, Tennessee. 2005-2008.

 YEAR       HY-M     HY-F    HY-U     AHY-U      AHY-M        AHY-F    TOTALS     RETURNS       SY-M     SY-F
  2005        5        2        5                                        12
  2006        1        1        3                               3         8            2           2
  2007        3       11        8                    1                   23
  2008        4        4        3        1           1          1        14            2           1       1
TOTALS        13      18       19        1           2          4        57            4           3       1

HY=hatch year, AHY=after hatch year, i.e. adult of undetermined years, SY=second year, M=male, F=female, U=undetermined
The capture of a pin feathered, fledgling NSWO, still in partial nestling plumage on
07-September 2006 also helps to support the possibility of nesting NSWO in the Big Bald
local area. According to personal communication with Project Owlnet, it would be
unlikely that juvenile fledgling owls would be migrating through the southern
Appalachian Mountains from northern nesting regions at such an early time in the
migration season. More likely, local fledgling birds might be dispersing from nearby
nesting sites at that time of year.

Returning second year owls, originally banded at Big Bald and recaptured in 2006 and in
2008, also indicate that adult birds have remained or returned to their natal area.

Efforts and recommendations for the 2009 season at Big Bald include:
    Continue trapping and banding during the autumn migration season
    Expand monitoring to the shoulder month of August
    Monitor for adult NSWO presence or absence during the early nesting season
    Monitor USFS nest boxes regularly for nesting activity
    Trap summer residents and use radio tracking to locate nests
    Radio track autumn hatch year captures to determine dispersal and survivorship


Acknowledgments

Northern Saw-whet Owl trapping at Big Bald Banding Station is supported by generous
donations to Southern Appalachian Raptor Research, a non-profit 501(3)c, formed by
private individuals passionate about raptors and their environment Many thanks to all the
volunteers that keep the station operating safely. The Big Bald Banding Station operates
with the cooperation and permission of the US Forest Service, Cherokee National Forest
and the Falcon Research Group, Bow, Washington. Big Bald Banding Station also
receives support for its work from Pisgah National Forest, Tennessee Wildlife Resources
Agency, North Carolina Wildlife Resources Commission, the US Bird Banding Lab, and
the Appalachian Trail Council.




References

Project Owlnet. http://www.projectowlnet.org/df.htm

Pyle, P. 1997. Identification Guide to North American Birds. Part 1. Columbidae to
Ploceidae. Slate River Press, Bolinas, CA.