Tuesday, December 5, 2017

2017 Fall Migration Summary

The 2017 fall migration banding season at the Kiawah Island Banding Station (KIBS) ended on Thursday. We banded at two sites on Kiawah Island again this fall:  Captain Sam's and Little Bear.  This was the 9th consecutive year of fall migration banding at the Captain Sam's site with banding occurring daily during the last 6 years.  This was the 3rd 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 8,393 birds and had 1,845 recaptures of 93 different species at both sites.

CAPTAIN SAM'S

Nets were opened for a total of 102 days from 15 August - 30 November.  We were shut down for only a total of 6 days.  Hurricane Irma, which was down graded to a tropical storm by the time it reached Charleston, shut us down for 4 consecutive days from 9 - 12 September.  This is the second year in a row that a hurricane/tropical storm has affected our banding.  I hope this trend does not continue in the future.     

We banded 4,796 new birds and had 1,216 recaptures of 83 different species.  The most commonly banded species were Common Yellowthroats (1,314), Yellow-rumped Warblers (704), and Gray Catbirds (685).  Those three species combined made up 56% of all the birds banded this season!

We also had a lot of recaptures from birds that were banded in previous seasons.  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.

Because we were open for four additional days than last year, our effort increased from 12,582.5 to 13,173.5 net-hours.  We banded 927 more birds this year compared to last year but only 200 birds more than the average for the previous 5 years.  The capture rate also increase compared to last year but was still 10.4 birds/100 net-hours lower than the 5-year average of 56.2 birds/100 net-hours.  Our capture rate has decreased every year starting in 2012 with the exception to this year however it was still lower than 2015.  The capture rate of recaptures is very consistent from year to year, so therefore all decreases in the total capture rate can be attributed to new birds.     

There were 12 days when over 100 birds were banded with 3 of those with over 200 birds banded. The best day of the season was on 16 September when we banded 237 and had 4 recaptures.  That was closely followed by 28 September when 236 birds were banded along with 16 recaptures.  Interestingly, 8 of the 12 busiest days occurred during the last two weeks of September.  Usually, early October is the busiest time of the season but October was kind of a "dud" this year.   

We banded two species that have never been banded at the Captain Sam's site during the fall:  Yellow-throated Vireo and Saltmarsh Sparrow.

Some other rare and notable species that were banded this fall include:  Eastern Whip-poor-will, Philadelphia Vireo, Clay-colored Sparrow, Louisiana Waterthrush, Mourning Warbler, Black-throated Green Warbler, and Canada Warbler.   


Top 10 Species Banded at Captain Sam's
1.  Common Yellowthroat (1,314)
2.  Yellow-rumped Warbler (704)
3.  Gray Catbird (685)
4.  Red-eyed Vireo (265)
5.  American Redstart (229)
6.  Palm Warbler (192)
7. Northern Waterthrush (146)
8.  Painted Bunting (128)
9.  Ruby-crowned Kinglet (125)
10.  Prairie Warbler (121)

LITTLE BEAR

Nets were opened for a total of 75 days from 22 August - 14 November.  We had 10 days cancelled due to weather including a 6 day stretch from 9-14 September for Hurricane Irma.  Wind also caused Little Bear to shut down for a few days scattered throughout the season.  After two 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 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 this season.

We banded 3,597 new birds and had 629 recaptures of 75 different species.  The most commonly banded species were Common Yellowthroats (948), Gray Catbirds (624), and Palm Warblers (326).    Those three species combined made up 53% of all the birds banded this season!

We logged 7,037.5 net-hours out at Little Bear this fall - an increase from the 6,011.8 net-hours in 2016.  The increase in effort this year was primary due to the fact that overall the nets were open a little longer on average each day compared to last year. 

Little Bear had a very good capture rate at 60.1 birds/100 net-hours.  This was higher than at Captain Sam's but substantially lower compared to 2015 and 2016 when we had a capture rate of 78.2 and 74.4 birds/100 net-hours, respectively.  Little Bear experienced a large decrease in the number of recaptures this year compared to last year (1,035 in 2016 and 629 in 2017).  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 10 days when over 100 birds were banded and no days with over 200 birds banded.  The best day was on 29 September when we banded 180 birds and had 4 recaptures.  The next best day was the previous day (28 September) when 167 birds were banded along with 9 recaptures. 

We banded 2 species never before banded at KIBS during the fall at Little Bear:  Belted Kingfisher and Eastern Bluebird.  This was the first Belted Kingfisher ever banded on Kiawah Island! 


Some other rare and notable species banded include:  Black-billed Cuckoo, Clay-colored Sparrow, Seaside Sparrow, Bobolink, Mourning Warbler, Kentucky Warbler, Blackburnian Warbler, and Black-throated Green Warbler. 

Top 10 Species Banded at Little Bear
1.  Common Yellowthroat (948)
2.  Gray Catbird (624)
3.  Palm Warbler (326)
4.  Yellow-rumped Warbler (273)
5.  Northern Waterthush (132)
6.  Painted Bunting (119)
7.  Prairie Warbler (114)
8.  Red-eyed Vireo (113)
9.  American Redstart (108)
10.  House Wren (83)

From left to right: Paul Carroll, Michael Gamble, Kristen Oliver, Brandon Connare, Hannah Conley, Aaron Given, Mattie VandenBoom

I would like to thank all those that made this season such a great success: a stellar team of banding assistants (Mattie VandenBoom, Michael Gamble, Kristen Oliver, Brandon Connare, Hannah Conley, and Paul Carroll;  the Town of Kiawah Island for proving funding for equipment and banding assistant stipends, and for allowing me to take on an extremely time consuming project;  the Kiawah Island Conservancy for providing funding for the housing of the banding assistants; Kiawah Partners and the Bear Island Holding Trust for allowing access to their property; and finally to all the volunteers that donated their time to either come out and help or just to observe.


-Aaron


SPECIES
CAPTAIN SAM’S
LITTLE BEAR
New
Recapture
New
Recapture
Common Ground-Dove
5
7
8
3
Black-billed Cuckoo
-
-
1
1
Yellow-billed Cuckoo
11
1
7
1
Chuck-will's-widow
1
-
-
-
Eastern Whip-poor-will
1
-
-
-
Sharp-shinned Hawk
3
-
1
1
Cooper's Hawk
-
-
1
-
Eastern Screech-owl
2
1
2
1
Belted Kingfisher
-
-
1
-
Yellow-bellied Sapsucker
9
-
1
-
Downy Woodpecker
7
14
3
3
Northern Flicker
3
-
-
-
Eastern Wood-Pewee
3
-
2
-
Acadian Flycatcher
2---
"Traill's" Flycatcher
27
-
32
3
Least Flycatcher
2
-
1
-
Eastern Phoebe
31
-
15
-
Great Crested Flycatcher
7
1
-
-
Eastern Kingbird
-
-
4
-
White-eyed Vireo
46
14
54
13
Yellow-throated Vireo
1
-
-
-
Blue-headed Vireo
9
-
4
-
Philadelphia Vireo
1
-
-
-
Red-eyed Vireo
265
22
113
4
Tree Swallow
2
-
-
-
Carolina Chickadee
11
65
8
18
Tufted Titmouse
3
-
23
-
House Wren
54
28
83
18
Marsh Wren
2
-
1
-
Carolina Wren
7
27
21
72
Blue-gray Gnatcatcher
1
-
4
-
Golden-crowned Kinglet
12
2
3
-
Ruby-crowned Kinglet
125
35
68
8
Eastern Bluebird
-
-
1
-
Veery
30
-
8
-
Gray-cheeked Thrush
4
-
1
-
Swainson's Thrush
43
-
30
1
Hermit Thrush
35
19
15
1
Wood Thrush
1
-
1
-
American Robin
1
-
1
-
Gray Catbird
685
416
624
252
Brown Thrasher
10
16
8
7
Northern Mockingbird
13
21
10
8
Eastern Towhee
9
16
38
7
Chipping Sparrow
1
-
-
-
Clay-colored Sparrow
1
-
2
-
Field Sparrow
1
-
-
-
Savannah Sparrow
3
-
-
-
Seaside Sparrow
-
-
1
-
Saltmarsh Sparrow
1
-
-
-
Song Sparrow
33
13
28
6
Swamp Sparrow
53
37
51
11
White-throated Sparrow
17
1
5
1
White-crowned Sparrow
3
-
4
1
Yellow-breasted Chat
5
1
13
2
Baltimore Oriole
6
-
5
-
Bobolink
-
-
1
-
Ovenbird
40
9
27
2
Worm-eating Warbler
4
-
3
-
Northern Waterthrush
146
-
132
25
Louisiana Waterthrush
1
-
-
-
Swainson's Warbler
2
1
1
-
Tennessee Warbler
4
-
5
-
Black-And-White Warbler
29
-
18
4
Prothonotary Warbler
7
-
4
-
Orange-crowned Warbler
18
10
7
2
Nashville Warbler
1
-
1
-
Mourning Warbler
1
-
1
-
Kentucky Warbler
-
-
1
-
Common Yellowthroat
1314
84
948
47
Hooded Warbler
6
-
6
-
American Redstart
229
29
108
2
Cape May Warbler
7
-
19
1
Northern Parula
27
-
19
1
Magnolia Warbler
14
-
7
-
Blackburnian Warbler
-
-
1
-
Yellow Warbler
52
9
57
1
Chestnut-sided Warbler
2
-
4
-
Blackpoll Warbler
-
-
1
-
Black-throated Blue Warbler
79
2
69
-
Palm Warbler (Western)
188
-
326
1
Palm Warbler (Yellow)
4
-
-
-
Yellow-rumped Warbler (Myrtle)
704
159
273
15
Yellow-throated Warbler
2
-
-
-
Prairie Warbler
121
11
114
11
Black-throated Green Warbler
2
-
3
-
Canada Warbler
1
-
-
-
Wilson's Warbler
1
-
-
-
Scarlet Tanager
2
-
1
-
Summer Tanager
4
1
-
-
Northern Cardinal
22
60
30
41
Blue Grosbeak
1
-
-
-
Indigo Bunting
24
-
19
-
Painted Bunting
128
63
119
36




BANDING STATISTICS
CAPTAIN SAM’S
LITTLE BEAR
TOTAL
# of Birds Banded
4,796
3,597
8,393
# of Recaptures
1,216
629
1,845
# of Species
83
75
93
Effort (net-hours)
13,173.5
7,037.5
20,211.0
Capture Rate (birds/100 net-hours
45.8
60.1
50.7
# of Nets
26-27
20
46-47
# of Days Operated
102
75
-
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.