Behavioral Ecology and Sociobiology
Supplementary material
Foraging distribution of a tropical seabird supports Ashmole’s hypothesis of population
regulation
Steffen Oppel1,*, Annalea Beard2, Derren Fox3, Elizabeth Mackley1, Eliza Leat3, Leeann Henry2,
Elizabeth Clingham2, Nathan Fowler3, Jolene Sim3, Julia Sommerfeld4, Nicola Weber3, Sam
Weber3, Mark Bolton1
1
RSPB Centre for Conservation Science, Royal Society for the Protection of Birds, The Lodge,
Sandy, Bedfordshire, SG19 2DL, U.K.
2
Environmental Management Division - Marine Section, St Helena Government, Jamestown, St
Helena, STHL 1ZZ, South Atlantic
3
Ascension Island Government Conservation Department, Georgetown, Ascension Island, South
Atlantic, ASCN 1ZZ, South Atlantic
4
Research and Technology Centre, University of Kiel, Büsum, Germany
*Corresponding author, email: steffen.oppel@rspb.org.uk
Figure S1 Bathymetry around the seabird islands of St Helena and Ascension in the South
Atlantic Ocean
Sea surface temperature (deg C)
28
Nov 2011
28
27
27
26
26
25
25
24
24
23
23
22
22
21
21
20
20
0-25
28
25-50
50-100
100-150
150-300
Jan 2014
Mar 2013
0-25
28
25-50
27
26
26
25
25
24
24
23
23
22
22
Ascension
21
21
St Helena
20
20
25-50
50-100
100-150
150-300
100-150
150-300
50-100
100-150
150-300
Mar 2014
27
0-25
50-100
0-25
25-50
Distance from colony (km)
Figure S2 Mean (± standard deviation) sea surface temperature (4x4 km gridded 8-day average
derived from MODIS Aqwa satellite imagery, see Dodge et al. 2013) in radial distance bands
around the seabird islands of St Helena and Ascension in the South Atlantic Ocean, during the
four seasons when we tracked birds with GPS loggers
Chlorophyll-a concentration (mg / l)
0.20
Nov 2011
0.20
0.18
0.18
0.16
0.16
0.14
0.14
0.12
0.12
0.10
0.10
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0.00
0.00
0-25
0.20
25-50
50-100
100-150
Jan 2014
0-25
0.20
0.18
0.18
0.16
0.16
0.14
0.14
0.12
0.12
0.10
0.10
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0.00
0.00
0-25
25-50
50-100
100-150
Mar 2013
25-50
50-100
100-150
50-100
100-150
Mar 2014
Ascension
St Helena
0-25
25-50
Distance from colony (km)
Figure S3 Mean (± standard deviation) chlorophyll-a concentration (4x4 km gridded 8-day
average derived from MODIS Aqwa satellite imagery, see Dodge et al. 2013) in radial distance
bands around the seabird islands of St Helena and Ascension in the South Atlantic Ocean,
during the four seasons when we tracked birds with GPS loggers
-10
-20
-15
y
Latitude
-20
-15
y
-10
-5
Mar 2013
-5
Nov 2011
-15
-10
-5
-15
x
-10
-5
x
-10
-20
-15
y
-20
-15
y
-10
-5
Mar 2014
-5
Jan 2014
-15
-10
x
-5
-15
Longitude
-10
-5
x
Figure S4 Sea surface temperature (4x4 km gridded monthly average derived from MODIS
Aqua satellite imagery, obtained from
http://coastwatch.pfeg.noaa.gov/erddap/griddap/erdMHsst4mday.html) around the seabird
islands of St Helena and Ascension in the South Atlantic Ocean during the four seasons when
we tracked birds with GPS loggers
-10
-20
-15
y
Latitude
-20
-15
y
-10
-5
Mar 2013
-5
Nov 2011
-15
-10
-5
-15
x
-10
-5
x
-10
-20
-15
y
-20
-15
y
-10
-5
Mar 2014
-5
Jan 2014
-15
-10
x
-5
-15
Longitude
-10
-5
x
Figure S5 Mean Chlorophyll-a concentration (4x4 km gridded monthly average derived from
MODIS Aqua satellite imagery, obtained from
http://coastwatch.pfeg.noaa.gov/erddap/griddap/erdMHchlamday.html) around the seabird
islands of St Helena and Ascension in the South Atlantic Ocean during the four seasons when
we tracked birds with GPS loggers