Tuesday, December 4, 2018

2018 Fall Migration Summary

The 2018 fall migration banding season at the Kiawah Island Banding Station (KIBS) ended on Friday, 30 November. We banded at two sites on Kiawah Island again this fall:  Captain Sam's and Little Bear.  This was the 10th consecutive year of fall migration banding at the Captain Sam's site with banding occurring daily during the last 7 years.  This was the 4th season for the Little Bear site which we initiated during the fall of 2015.  The two sites are located at each end of island about 8 miles apart (Captain Sam's on the west end, Little Bear on the east end).  Both sites are situated in coastal scrub/shrub and high marsh habitats, however, the Little Bear site is in an earlier stage of succession. Collectively, we banded 6,744 birds and had 1,857 recaptures of 91 different species at both sites.  This season was substantially slower in terms of the number of birds banded for both sites.  Captain Sam's and Little Bear combined, experienced a 20% decrease in the number of birds banded from last year, and a 9% decrease on average of the last 4 years.  September and October were unseasonably warm, and we lacked any major cold front until mid October.  In a three day period from 12-14 October, 25% of the birds were banded for the entire season.  Typically, cold fronts occur every 7-10 days during the fall season bringing with it new migrants.  But that was not the case this year.  Cold fronts were few and far between resulting in odd weather patterns this fall. 

CAPTAIN SAM'S

Nets were opened for a total of 100 days from 15 August - 30 November.  There were only 8 days in which banding did not occur.  Hurricane Florence shut us down for 7 consecutive days from 11- 17 September.  Hurricane Florence was a strong Category 4 storm that made landfall on 14 September in Wrightsville Beach, NC.  The storm weakened to a Category 1 just prior to making making landfall and then turned to the south, and moved over central South Carolina as a tropical storm.  Even though this storm did not affect the Charleston area to the degree that was predicted, the intensity and unpredictable track of the storm caused mandatory evacuations for the all coastal areas of South Carolina.   This is the third year in a row that a hurricane/tropical storm has affected our banding.  These storms are now becoming more of a trend rather than an exception.

We banded 4,033 new birds of 80 different species.  The most commonly banded species were Gray Catbird (922), Common Yellowthroat (826), and Yellow-rumped Warbler (615).  Those three species combined made up 59% of all the birds banded this season.  For the first time ever, Common Yellowthroats were not the most commonly banded species.  In fact their numbers were down 29% on average over the last 7 years, and 37% from last season.  Alternatively, Gray Catbird numbers were up 26% from the 7-year average, and 35% from last season.  Yellow-rumped Warbler numbers continue to show decreases and were down 9% over the last 7 years, and 20% from last year.   

The overall effort decreased this year from 13,173.5 net-hours in 2017 to 12,559.9 net-hours.  This decrease in effort is essentially a result of banding two less days than last year.  Additionally, because it was so hot in September and October this fall, we had to close down earlier in the day than what we normally would do.  We banded 762 fewer birds this year compared to last year and 511 birds fewer than the average for the previous 7 years.  The capture rate only decreased by 2.9 birds/100 net-hours compared to last year but was 10.1 birds/100 net-hours lower than the 7-year average of 52.7 birds/100 net-hours.  Our capture rate has decreased every year starting in 2012 with exception to last year when we experienced a small increase from 2016.  The capture rate of recaptures is very consistent from year to year, therefore all decreases in the total capture rate can be attributed to new birds. 

We also had 1,326 recaptures which is the most recaptures we have ever had in a season.  Gray Catbirds made up 42% of all recaptures which is a much higher average than in previous seasons.  Because we banded so many of them this year, and the fact that this species winters on site, this increase could be expected.  We recaptured many individuals that were banded in previous years.  It will take a while to sort through all those records to determine how many unique returns we actually had as some of those were undoubtedly captured more than once during the fall.  Two notable recaptures were a Common Yellowthroat and a Tree Swallow that were not banded at KIBS.  Unfortunately, we still do not know the origin of the Tree Swallow as the Bird Banding Laboratory has not received the data from the original bander.  The Common Yellowthroat was banded at the Chester River Field Research Station in Chestertown, Maryland on 5 May 2016.

There were only 4 days this fall when over 100 birds were banded compared to 12 days last fall.  The best day of the season was on 13 October when we banded 406 birds and had 15 recaptures.  This is the 2nd highest total ever in KIBS history with the biggest day occurring on 6 October 2015 when 436 bird were banded.  The next two busiest days occurred 12 and 14 October when 276 and 248 birds were banded respectively.  That was probably the busiest three-day period in KIBS history when 23% of the birds for the entire season were banded during those days.

We captured one species that have never been banded at the Captain Sam's site during the fall:  Eastern Bluebird. 

Some other rare and notable species that were banded this fall include:  three Red-breasted Nuthatches (8 previous banding records), one Clay-colored Sparrow (6 previous), one Grasshopper Sparrow (3 previous), one Lincoln's Sparrow (1 previous), two Dark-eyed Juncos (1 previous), one Brown-headed Cowbird (1 previous), one Black-throated Green Warbler (4 previous), and one Rose-breasted Grosbeak (8 previous). 

Species notably absent this year included:  Common Ground-Dove, Chuck-will's-widow, Northern Flicker. Yellow-bellied Flycatcher, Marsh Wren, Baltimore Oriole.  There has been a steady decline of Common Ground-Doves since we started banding in 2009.  I didn't see or hear a ground-dove all season which is alarming.  I fear that they may be gone from the site.




Top 10 Species Banded at Captain Sam's
1.  Gray Catbird (922)
2.  Common Yellowthroat (826)
3.  Yellow-rumped Warbler (615)
4.  Painted Bunting (175)
5.  American Redstart (147)
6.  Red-eyed Vireo (124)
7. Palm Warbler (108)
8.  Prairie Warbler (76)
9.  Black-throated Blue Warbler (63)
10.  Ruby-crowned Kinglet (60)

LITTLE BEAR

Nets were opened for a total of 73 days from 22 August - 14 November.  We had 12 days cancelled due to weather including a 7 day stretch from 11-17 September for Hurricane Florence.  Wind also caused Little Bear to shut down for a few days scattered throughout the season.  After three years in a row of tropical storms and hurricanes, the Little Bear site has suffered from saltwater intrusion which has killed many of the wax myrtles, marsh elders, and Baccharis around the site.  Wax myrtles are the dominant plant at Little Bear and the reduced cover around the nets have caused the nets to become much more exposed to the elements - wind and heat being the biggest threats.  Because of this, Little Bear had to close down early many days when the temperature got too warm to safely (for the birds) capture birds.  Additionally, winds with a northerly component to them affected the nets considerably.  The predominant winds in the fall are usually from the north (especially following a cold front) therefore the wind seemed to be a constant factor at Little Bear again this season.

We banded 2,711 new birds of 78 different species.  The most commonly banded species were Gray Catbirds (783), Common Yellowthroats (536), and Palm Warblers (183).    Those three species combined made up 55% of all the birds banded this season.  Similar to Captain Sam's, Gray Catbird numbers exhibited a 21% increase from the 4-year average, and an increase of 25% from last year.  Common Yellowthroats, on the other hand, decreased by 15% from the 4-year average, and 43% from last fall.  Palm Warblers were right in-line with the 4-year average but had a 44% decrease from last fall.  Last year was an unprecedented year for Palm Warblers.  In 2015 and 2016, Yellow-rumped Warblers were in the top three species banded.  In fact they were the most commonly banded bird in 2016 with 659.  This year only 113 Yellow-rumped Warbler were banded and 273 in 2017.  Their numbers have decreased by 69% over the last 4 years and 59% from last year.  This decrease can be attributed to saltwater intrusion in 2015 and 2016 that killed many of the mature wax myrtles.  Yellow-rumped Warblers feed on the berries of wax myrtles and without that resource available a decrease was evident.  There is some good news though.  New wax myrtles are starting to come back and as long as they can get big enough to produce fruit - the yellow-rumps will come back too. 

We logged 5,148.6 net-hours out at Little Bear this fall - an dramatic decrease from the 7,037.5 net-hours in 2017.  The decrease in effort this year was primarily due to the fact that the nets were closed down early most days in September and October due to excessive heat.  We banded 886 fewer birds this year compared to last year and 319 birds fewer than the average for the previous 4 years.  Little Bear had a very good capture rate at 63.0 birds/100 net-hours.  Despite banding substantially fewer birds compared to last fall, the capture rate actually increased by 2.9 birds/100 net-hours.  This increase was due to a combination of factors:  (1) a majority of the birds are normally captured early in the morning, (2)  the nets were closed early many days due to heat. Overall, the capture rate decreased by 9% from the 4-year average this year.

Little Bear experienced a large decrease in the number of recaptures this year compared to last year (633 in 2017 and 531 in 2018).  This is the 2nd year in a row where we have seen a substantial decrease in the number of recaptures.  As I stated last year, the only thing I can think of to explain this is that the decrease in cover caused by the wax myrtles dying reduced the quality of the habitat enough to negatively affect the bird's stopover time.   

There were only 5 days when over 100 birds compared to 10 day last fall.  The best day of the season was on 13 October when we banded 400 birds and had 4 recaptures.  This was a record breaking day for Little Bear with the next busiest day coming back on 23 October 2016 when 207 birds were banded .  The next two busiest days occurred 12 and 14 October when 181 and 145 birds were banded respectively.  Another 145 birds were also banded on 19 September.

We captured five species never before banded at Little Bear during the fall:  Kirtland's Warbler, Cassin's Vireo (possible), Red-breasted Nuthatch (2), Dark-eyed Junco, and Rose-breasted Grosbeak.  This was the first Kirtland's Warbler ever banded on Kiawah Island.  In fact, this was the first Kirtland's Warbler to ever have been seen on Kiawah Island!  Cassin's Vireo is a western species that can look similar to its eastern counterpart the Blue-headed Vireo.  Because the two species can look similar, we are using the term "possible" until more research can be done and more resources can be consulted before determining the correct identification.  It is possible that we may never know for sure but the overall dull plumage fits the profile of Cassin's better than Blue-headed.

Some other rare and notable species banded include:  Saltmarsh Sparrow (1 previous banding record), Lincoln's Sparrow (1 previous), Mourning Warbler (1 previous), Black-throated Green Warbler (5 previous), and Chestnut-sided Warbler (6 previous).

Species notably absent: Common Ground-Dove, Blue-gray Gnatcatcher. 

Top 10 Species Banded at Little Bear
1.  Gray Catbird (783)
2.  Common Yellowthroat (536)
3.  Palm Warbler (183)
4.  Yellow-rumped Warbler (113)
5.  Painted Bunting (110)
6.  American Redstart (108)
7.  Red-eyed Vireo (77)
8. Yellow Warbler (64)
9.  Prairie Warbler (64)
10. Indigo Bunting (47)

Without the cooperation of many people and entities, this work would not be possible.  The success of this project relies on their commitment, and I am in a debt of gratitude to everyone involved.  First, I'd like to thank my team of banding assistants (Michael Gamble, Kristen Attinger, Meredith Heather, Danae Mouton, Joel Throckmorton, and Joanne Hamilton).  Their hard work over the course of this long season was outstanding.  Next, I'd like to acknowledge the Town of Kiawah Island for providing funding for equipment and banding assistant stipends, the Kiawah Island Conservancy for providing funding for the housing of the banding assistants, and the Kiawah Partners and the Bear Island Holding Trust for allowing access to their property for banding.  And last but not least, I'd like to thank the many volunteers that donated their time to come out and help.  Chris Snook, Ryan Donnelly, and Nancy Raginski put in many hours volunteering during times when they were needed the most.  I could always count on them to show up and help make those busy days go much more smoothly and efficiently.

The 2018 KIBS Banding Crew
From left to right:  Meredith Heather, Danae Mouton, Michael Gamble, Joel Throckmorton, Aaron Given, Kristen Attinger.  Not pictured: Joanne Hamilton.

SPECIES
CAPTAIN SAM’S
LITTLE BEAR
New
Recapture
New
Recapture
Mourning Dove
2
1
-
-
Yellow-billed Cuckoo
34
4
38
10
Sharp-shinned Hawk
2
-
1
-
Cooper's Hawk
1
-
-
-
Eastern Screech-Owl
2
1
2
-
Yellow-bellied Sapsucker
7
-
6
-
Downy Woodpecker
9
19
2
1
Eastern Wood-Pewee
6
-
2
-
Acadian Flycatcher 
3
-
1
-
"Traill's" Flycatcher
15
-
20
3
Least Flycatcher
1
-
1
1
Eastern Phoebe
42
5
33
-
Great Crested Flycatcher
10
6
-
-
Eastern Kingbird
5-1-
White-eyed Vireo
42
8
39
18
Blue-headed Vireo
4
-
1
-
Cassin's Vireo (possible)
-
-
1
-
Red-eyed Vireo
124
12
77
4
Tree Swallow
48
1
-
-
Carolina Chickadee
14
34
7
17
Red-breasted Nuthatch
3
-
2
1
House Wren
52
21
35
7
Carolina Wren
11
55
13
46
Blue-gray Gnatcatcher
3
-
-
-
Golden-crowned Kinglet
2
-
3
-
Ruby-crowned Kinglet
60
17
15
-
Eastern Bluebird
1
-
-
-
Veery
8
-
4
-
Gray-cheeked Thrush
7
-
4
-
Gray-cheeked/Bicknell's Thrush
1
-
1
-
Swainson's Thrush
50
-
22
-
Hermit Thrush
16
20
6
-
Wood Thrush
3
-
7
-
American Robin
9
-
1
-
Gray Catbird
922
551
783
229
Brown Thrasher
9
9
5
2
Northern Mockingbird
31
23
19
4
House Finch
14
-
4
-
American Goldfinch
19
-
-
-
Eastern Towhee
17
22
6
5
Chipping Sparrow
-
-
1
-
Clay-colored Sparrow
1
-
-
-
Field Sparrow
3
-
1
-
Savannah Sparrow
2
-
1
-
Grasshopper Sparrow
1
-
-
-
Saltmarsh Sparrow
-
-
1
-
Song Sparrow
33
13
32
2
Lincoln's Sparrow
1
-
1
-
Swamp Sparrow
33
19
38
9
White-throated Sparrow
10
2
1
-
White-crowned Sparrow
-
-
2
-
Dark-eyed Junco
2
-
1
-
Yellow-breasted Chat
4
3
5
1
Baltimore Oriole
-
-
1
-
Brown-headed Cowbird
1
-
-
-
Ovenbird
17
2
13
-
Worm-eating Warbler
2
-
-
-
Louisiana Warbler
1
-
-
-
Northern Waterthrush
59
-
29
3
Black-and-white Warbler
18
-
5
-
Prothonotary Warbler
1
1
3
-
Swainson's Warbler
1
1
-
-
Tennessee Warbler
7
3
1
-
Orange-crowned Warbler
17
9
14
3
Nashville Warbler
-
-
2
-
Mourning Warbler
-
-
1
-
Common Yellowthroat
826
59
536
20
Hooded Warbler
2
-
4
-
American Redstart
147
3
108
1
Kirtland's Warbler
-
-
1
-
Cape May Warbler
20
1
44
11
Northern Parula
30
-
15
-
Magnolia Warbler
17
-
12
-
Bay-breasted Warbler
2
-
1
-
Yellow Warbler
27
-
64
3
Chestnut-sided Warbler
-
-
1
-
Blackpoll Warbler
6
6
12
5
Black-throated Blue Warbler
63
2
39
-
Palm Warbler (Western)
107
-
180
-
Palm Warbler (Yellow)
1
-
3
-
Pine Warbler
-
-
2
-
Yellow-rumped Warbler (Myrtle)
615
187
113
5
Yellow-throated Warbler
-
-
1
-
Prairie Warbler
76
9
64
6
Black-throated Green Warbler
1
-
1
-
Wilson's Warbler
1
4
1
-
Summer Tanager
4
-
-
-
Scarlet Tanager
6
-
1
-
Northern Cardinal
37
85
32
32
Rose-breasted Grosbeak
1
-
1
-
Blue Grosbeak
4
-
3
-
Indigo Bunting 
42
-
47
-
Painted Bunting
175
108
110
82
Blackburnian Warbler
-
-1-
 

BANDING STATISTICS
CAPTAIN SAM’S
LITTLE BEAR
TOTAL
# of Birds Banded
4,033
2,711
6,744
# of Recaptures
1,326
531
1,857
# of Species
80
78
91
Effort (net-hours)
12,559.9
5148.6
17,708.5
Capture Rate (birds/100 net-hours
42.6
63.0
48.6
# of Nets
28
20
48
# of Days Operated
100
73
-
Dates of Operation
8/15-11/30
8/22-11/14
-
Please note that these number are still preliminary and may change after the data is thoroughly proofed.