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Electronic Supplementary Materials:
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Table S1. Geolocator deployment locations, year, type, number of units deployed,
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geolocators retrieved (does not include birds who lost tags) and total sample size for winter
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roosts (excludes tags that failed prior to spring migration).
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Year(s)
deployed
Latitude
Longitude
Weight (g),
stalk length
(mm), model
Number
deployed
Geolocators
retrieved
Sample
size
with
tracking
data
2007-8
41° 53’ 08”N
80° 07’ 46”W
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5
5
2009-10
41° 53’ 08”N
42° 08’ 59”N
42° 08’ 59”N
80° 07’ 46”W
80° 07’ 58”W
80° 07’ 58”W
1.1-1.5, 20, MK
10S/14S
0.6-1.1, 0-8, MK
20/10S
1.2, 9, MK10S
47
18
14
54
19
15
27° 41’ N
97° 24’ W
1.1, 5-10,MK10S
30
10
8
38° 36’ 47”N
38° 36’ 47”N
77° 15’ 46” W
77° 15’ 46” W
0.9-1.1, 0-8, MK12
1.2, 9, MK10S
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50
19
12
9
10
49° 21’ 0”N
48° 59’ 46”N
124° 21’ 25”W
123° 48’ 50”W
1.0-1.2, 5-10,
MK10S/12S/20S
50
8
6
45° 36’ 00”N
45° 36’ 59”N
96° 42’ 00”W
98° 17’ 59”W
1.2, 9, MK10S
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10
9
45° 23’ 59”N
46° 08’ 59”N
45° 15’ 36”N
45° 16’ 43”N
94° 12’ 00”W
93° 43’ 11”W
92° 57’ 22”W
92° 59’ 6”W
1.2, 9, MK10S
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5
5
40° 23’ 59”N
74° 00’ 00”W
1.2, 9, MK10S
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11
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33° 52’ 51”N
96° 48’ 1”W
OU/Cornell
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3
3
421
120
95
Pennsylvania
2011
Texas
2009-10
Virginia
2010
2011
British Columbia
2009-11
South Dakota
2011
Minnesota
2011
New Jersey
2011
Oklahoma
2011
TOTAL
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9
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Table S2. Return rate (number re-sighted in subsequent years) of geolocator versus non-
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geolocator purple martins from deployments in Pennsylvania (2009-2012), our most
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intensively monitored and long-term study site. Data are reported only for birds at least
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two years old at time of deployment and/or banding. Band re-sighting was conducted at
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focal colonies where geolocators were deployed, nearby breeding colonies and a pre-
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migratory roost. Return rate of geolocator birds was not lower than non-geolocator birds,
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and in one year was significantly higher.
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Deploy
Geo-
Number
No
Number
-ment
locators
Resighted
Geolocators
Resighted
Year
Deployed
(%)
(leg bands
(%)
X2
P value
only)
2009
26
16 (61%)
144
46 (32%)
7.097
0.008
2010
17
5 (29%)
164
42 (25%)
0.003
0.96
2011
44
18 (41%)
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16 (48%)
0.185
0.67
Total
87
39 (45%)
341
104 (30%)
5.769
0.02
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Table S3. Geolocator accuracy based on ground truthing after deployment and before onset
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of migration of purple martins. Only breeding colonies with n > 5 geolocators retrieved are
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included.
State/
n
Province
Breeding
Breeding
Latitude Error
Longitude Error
Latitude
Longitude
(km; mean ± se)
(km; mean ± se)
SD
5
45.6
98.3
27.2 (11.3)
64.8 (14.4)
PA
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42.1
80.1
47.5 (5.8)
41.6 (7.1)
NJ
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40.4
74.0
19.9 (5.3)
21.5 (4.0)
VA
19
38.6
77.2
49.1 (10.0)
73.6 (8.9)
TX
8
27.7
97.4
58.3 (23.5)
45.5 (8.1)
BC
7
49.0
123.8
15.1 (6.4)
23.0 (7.7)
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Band Recovery
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Band recovery data for purple martins were obtained from the U.S. Geological
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Survey Bird Banding Lab. Total number of recoveries was 2884 (2383 banded as nestlings,
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501 banded as adults) with 22 of these occurring in South America. Using our geolocator
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data, we determined that 100% of individuals from central and northern populations (MN,
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SD, PA, NJ, VA) arrived at their first non-breeding roost in South America by 28 October, and
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80% arrived by 15 October. To be conservative, we excluded band recoveries that occurred
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before 28 October (n = 2) as individuals could have been in transit. Similarly, we excluded
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recoveries occurring in mid or late April (n = 4) because many tracked individuals (16 of
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50; 32%) began spring migration by early April. For very southern populations (OK, TX) all
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recoveries in South America occurred after 10 October; all birds tracked with geolocators
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arrived at their first roost by this date. Four additional records were excluded since
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recovery date in South America was not recorded, yielding a final sample of 12 recoveries
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after autumn migration but before spring migration.
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46
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Figure S1. Band recovery data (n = 12) for purple martins banded at breeding sites and
recovered in South America outside the likely migration period. Only 1 of 12 individuals
was banded at its breeding site as an adult; all others were first banded as nestlings. Dashed
lines are individuals on their first migration, solid lines are birds recovered on their second
or greater migration. Red lines indicate the western subspecies Progne subis arboricola, all
others are the eastern subspecies P. s. subis. Recovery data were obtained from the USGS
Bird Banding Lab.
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Figure S2. Correlation between (a) breeding and wintering latitude and (b) breeding and
wintering longitude for individual purple martin from the eastern subspecies (P. s. subis, n = 89).
Males are triangle symbols, females are circles. Statistics reported for Spearman rank correlation.
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Additional Acknowledgements
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We thank the many dedicated volunteers who assisted with geolocator deployment and
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retrieval: J. Bahamon, Caryl Buck, L. Chambers, William Dalton, E. Demers, L. Fuiman, J. Galli,
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Dawn Ho, P. Holzer, Allen Jackson, A. Loewen, M. Victoria McDonald, Candace Mickle, Glenn
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Mickle, J. Morgan, K. Morgan, Sarah Morton, Douglas Morton, B. Ortego, Emily Pifer, R. Segal,
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B. Smith, S. A. Tarof, Mary Shaheen White, Harmon Willey, and Thomas Wood. In Minnesota,
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Larry Leonard of Brainerd, Dick Doll of Willmar, and Lee Bakewell of Forest Lake made
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their colonies available for this research, and banding was conducted under Michael North’s
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permit. In South Dakota work was conducted under Eileen Dowd Stukel’s permit, Dennis
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Mammenga of Sioux Falls made his colony available for research, and Dennis, Joy, Luverne,
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Tim & Riley Mammenga, Dan Nelson, Kathy Hegge and Chris Hull assisted with fieldwork
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and data management.
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We also thank the many private donors who contributed funds for geolocator purchase.
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New Jersey: John Tautin, Bill and Janet Trantor, Harmon and Nina Willey, Janis and Jennifer
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Brennan, Barbara Bonforte, Jerry Kokes, David Cafaro, William Dallton, Michael Miller,
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Jason Gancarz, William Pennisi, William Hintz, George and Nancy Nebel, Vincent and Ann
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Fuschetti, William Dietrich; Minnesota: Lee Bakewell.
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