Timothée R. Cook Maike Hamann Lorien Pichegru Francesco Bonadonna David Grémillet Peter
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GPS and time-depth loggers reveal underwater foraging plasticity in a flying diver, the Cape Cormorant
Timothée R. Cook · Maike Hamann · Lorien Pichegru · Francesco Bonadonna · David Grémillet · Peter G. Ryan
T. R. Cook (corresponding author) Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, Private Bag X3, University of Cape Town, Rondebosch 7701, Cape Town, South Africa e–mail: [email protected] phone: (+27) (0) 21 650 3619 fax: (+27) (0) 21 650 3295
Supplementary material
Fig. S1–S2 Table S1–S3 2
E18.18
1000 m
Fig. S1 Detail of the foraging track of a Cape Cormorant Phalacrocorax capensis from Malgas Island superimposed on the chart from BlueChart Atlantic 7.0. The depth of seafloor beneath each dive was determined manually to the nearest value on the chart. The advantage of using this chart is the high resolution of the bathymetry compared to other available digital interpolated bathymetric data. Navigational charts display a high resolution in inshore waters, precisely because knowledge of depth of seafloor is crucial for coastal navigation. Every value of depth on the map has actually been measured physically by boat. 3
Table S1 Summary of dive parameters of adult chick–rearing Cape Cormorants equipped with GPS and TDR on three islands off South Africa during the 2008 breeding season. Means are presented ± SE.
GPS duration Max. Body GPS Foraging Dives with Mean dive Benthic Pelagic before battery Dives Max. dive Mean dive dive Island mass sampling trips GPS duration dives dives failure (or bird recorded depth (m) depth (m) duration (g) interval (s) detected position (%) (s) (%) (%) recapture) (h:min) (s) Dassen 1385 10 12:23 2 105 81.9 20.1 12.4 ± 3.5 49 35.6 ± 7.7 92.4 7.6 Dassen 1245 10 11:03 1 242 63.6 16.4 6.4 ± 3.1 45 21.4 ± 8.8 27.7 72.3 Dassen 1400 10 10:39 1 87 52.9 22.7 9.7 ± 4.3 63 34.4 ± 7.3 85.1 14.9 Dassen 1155 10 11:30 1 219 37.9 32.7 4.5 ± 5.0 62 18.3 ± 10.4 5.5 94.5 Dassen 1025 no GPS data ─ ─ 182 ─ 21.2 9.2 ± 4.3 51 28.5 ± 10.5 57.1 42.9 Dyer 1300 10 9:55 3 72 98.6 27.7 17 ± 5.2 62 33.6 ± 8.8 97.2 2.8 Dyer 1050 10 10:32 2 99 90.9 28.5 11.6 ± 5.9 58 25.6 ± 10.5 54.5 45.5 Dyer 1320 10 7:31 1 24 79.2 34.0 20.9 ± 8.1 63 40 ± 12.3 75.0 25.0 Dyer 1080 10 9:40 2 54 100.0 35.5 16.8 ± 5.6 71 36.9 ± 10.6 94.4 5.6 Dyer 1140 10 10:23 2 131 61.8 37.3 11.4 ± 7.8 76 25.6 ± 14 47.3 52.7 Dyer 1090 10 9:36 1 199 76.9 28.6 9.8 ± 6.7 59 24 ± 11.7 16.6 83.4 Dyer 1430 10 9:04 2 31 100.0 30.8 16 ± 6.3 60 31.2 ± 11.9 96.8 3.2 Dyer 1380 10 9:28 3 45 93.3 32.7 24 ± 6.2 71 45.3 ± 13.2 97.8 2.2 Dyer 1320 10 9:06 1 118 78.8 32.1 16.2 ± 5.9 60 37 ± 10.8 87.3 12.7 Dyer 1290 10 9:46 3 76 94.7 25.8 15.8 ± 4.8 53 34.7 ± 8.9 97.4 2.6 Dyer 1200 10 9:10 1 69 87.0 36.9 19.6 ± 7.1 72 37.8 ± 11.9 94.2 5.8 Dyer 1170 10 7:20 2 21 100.0 32.9 21.2 ± 6.5 61 36.8 ± 11.6 100.0 0.0 Dyer 1350 10 9:12 2 70 98.6 31.3 16.5 ± 5.6 61 34 ± 9.4 95.7 4.3 Dyer 1260 10 9:35 2 95 36.8 31.8 12.2 ± 7.6 74 27 ± 13.6 33.7 66.3 Dyer 1180 10 10:12 2 50 52.0 31.3 23.2 ± 6.2 78 45.8 ± 13.1 92.0 8.0 Dyer 1000 10 9:30 1 127 71.7 36.7 16.3 ± 6.9 76 35.7 ± 10.8 78.0 22.0 4
Table S1 (continued). GPS duration Max. Body GPS Foraging Dives with Mean dive Benthic Pelagic before battery Dives Max. dive Mean dive dive Island mass sampling trips GPS duration dives dives failure (or bird recorded depth (m) depth (m) duration (g) interval (s) detected position (%) (s) (%) (%) recapture) (h:min) (s) Malgas 1190 1 5:53 1 125 65.6 27.1 14.6 ± 8 66 30.8 ± 15.1 76.0 24.0 Malgas 1160 60 5:43 1 30 46.7 28.2 20.2 ± 8.4 64 39 ± 15.5 86.7 13.3 Malgas 1300 60 7:56 1 88 27.3 16.3 4.6 ± 5.3 48 16.2 ± 13.6 31.8 68.2 Malgas 1340 120 8:12 1 111 52.3 21.9 9.5 ± 8.5 55 25.6 ± 18 48.6 51.4 Malgas 1240 120 14:21 1 138 38.4 27.8 4.7 ± 6.4 63 14.5 ± 13.2 21.0 79.0 Malgas 1140 120 16:27 2 131 46.6 17.2 8.6 ± 6.4 69 27.5 ± 17.5 48.9 51.1 Malgas 1190 no GPS data ─ ─ 55 ─ 30.3 16.6 ± 8.4 68 36.3 ± 14.4 80.0 20.0 Malgas 1130 no GPS data ─ ─ 32 ─ 20.0 14.1 ± 5.9 55 34.8 ± 14.1 78.1 21.9 5
Table S2 Mass and composition of stomach contents of Cape Cormorants equipped with GPS and TDR and that spontaneously regurgitated upon recapture. The last column gives the proportion of benthic dives, which occurred in the foraging trip preceding recapture of the study bird and collection of the content.
Stomach content Proportion of Cape Proportion of Colony Bird mass (g) Anchovy (%) benthic dives (%) Malgas F3-599 40 100 86 Dyer F1-599 50 100 91 Dyer F19-605 120 100 100 Dyer F15-600 70 100 100 Dyer F19-605 50 100 19 Dyer F1-599 60 100 47 6
Table S3 Contribution (% by mass) of different prey items to the diet of the Cape Cormorants from Western South Africa for the period 1984–1992 (from Crawford and Dyer 1995).
Prey item 1984 1985 1986 1987 1989 1990 1991 1992 Cape Anchovy 48 97 50 99 30 70 59 60 South African Sardine 1 0 50 1 70 0 37 21 Horse Mackerel 0 1 0 0 0 24 0 16 Hakes 50 0 0 0 0 0 0 0 Other 1 2 0 <1 0 6 4 3 7
(a) 90 1.8
80 ) 1.6 1 - ) s
s 1.4 70 (
m n 60 ( 1.2 Benthic
o i e t 50 t 1.0 a a r r
u 40 Benthic t 0.8 d n
e e 30 0.6 Pelagic c v i s e D 20 0.4
Pelagic D 10 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40
30 2.0 1.8 ) ) 1 s 25 -
( 1.6
s
n 1.4 o
m Benthic i 20 ( t 1.2 a e r Benthic t u
15 a 1.0 r d
t 0.8 n m e
o 10
t 0.6 Pelagic Pelagic c t s o 0.4 A B 5 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40 Dive depth (m)
(b) 90 1.8
80 ) 1.6 1 - ) s
s 1.4 70 (
Benthic m n 60 ( 1.2
o i e t 50 t 1.0 a Benthic a r Pelagic r
u 40 t 0.8 d n Pelagic e e 30 0.6 c v i s e D 20 0.4 10 D 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40
30 2.0 1.8 ) ) s 25 1 -
( 1.6
s
n Pelagic 1.4 o m
i 20 ( t 1.2 Benthic a e r t u 15 a 1.0 r d
t 0.8 n m e
o 10 Benthic Pelagic
t 0.6 c t s o 0.4 A B 5 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40 Dive depth (m) 8
(c) 90 1.8
80 ) 1.6 1 - ) s
s 1.4 70 (
m n 60 Benthic ( 1.2
o i
e Benthic t 50 t 1.0 a a r r
u Pelagic 40 t 0.8 d n
e e 30 0.6 c Pelagic v i s e D 20 0.4 10 D 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40
30 2.0 1.8 ) )
s 25 1 -
( 1.6
s
n 1.4 o m
i 20 ( t Benthic 1.2 a
Benthic e r
Pelagic t u
15 a 1.0 r d
t 0.8 n m e
o 10
t 0.6 c t Pelagic s o 0.4 A B 5 0.2 0 0.0 0 10 20 30 40 0 10 20 30 40 Dive depth (m)
Fig. S2 Dive duration, descent rate, bottom duration, and ascent rate in relation to dive depth, for (a) U-shaped benthic (N = 957 dives from 29 birds; black circles) and pelagic dives (N = 169 dives from 22 birds; grey circles), (b) parabolic benthic (N = 242 dives from 28 birds; black circles) and pelagic dives (N = 327 dives from 19 birds; grey circles), and (c) V-shaped benthic (N = 389 dives from 28 birds; black circles) and pelagic dives (N = 742 dives from 26 birds; grey circles) made by Cape Cormorants. Means are presented ± SE.