Polar Biology: Electronic supplementary material
South Polar Skua breeding populations in the Ross Sea assessed from demonstrated relationship with penguin numbers
Deborah J. Wilson, Philip O’B. Lyver, Terry C. Greene, Amy L. Whitehead, Katie M. Dugger, Brian J. Karl, James R. F. Barringer, Roger McGarry, Annie M. Pollard,and David G. Ainley
Corresponding author:
Deborah J. Wilson
Landcare Research
Private Bag 1930
Dunedin 9054
New Zealand
Online resource 1.Dates of South Polar Skua surveys at 5 locations on Ross Island in 2011–12 and 2012–13, and at 3 locations at Cape Bird, Ross Island, in 2013–14.
2011–12 / 2012–13 / 2013–14Location / First survey / Second survey / First survey / Second survey
Cape Bird North / 16 December 2011 / — / 8 December 2012 / 12 December 2012 / 8 December 2013
Cape Bird Middle / 20 December 2011 / — / 8 December 2012 / 10 December 2012 / 6 December 2013
Cape Bird South / 21 December 2011 / — / 9 December 2012 / 11 December 2012 / 6, 9 December 2013
Cape Crozier / 8–13 December 2011 / — / 3–6 December 2012 / — / —
Cape Royds / 3–4 December 2011 / 4–6 December 2011 / 29–30 November 2012 / 1 December 2012 / —
Online resource 2.Nest detection functions (curves) fitted to observations (histograms) of nests of South Polar Skuas at three Cape Bird locations and at Cape Crozier and Cape Royds, on Ross Island, Antarctica. On each graph, curves and observations are plotted up to the perpendicular distance (m) from the transect line at which data were right-truncated for analysis. Detection functions shown are best models based on AICc, averaged over any covariates. ‘Original’ and ‘new’ at Cape Bird refer to original and new sets of transect lines; the latter were established for the second survey in 2012–13 and used again in 2013–14 (Table 3). Cape Crozier East and West were modelled separately.
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Online resource 3. Detection models for South Polar Skua nests at3 Cape Bird locations and at Cape Crozier and Cape Royds, on Ross Island, Antarctica. Models are ranked by ΔAICc. Model weight (AICc weight) is given only for models that were averaged in each set, i.e. those without uninformative parameters that increased AICc by ≤2 units, as noted. Models that were rejected on the basis of fit and shape are not listed (see Methods). ‘Original’ and ‘new’ at Cape Bird refer to original and new sets of transect lines; the latter were established for the second survey in 2012–13 and used again in 2013–14 (Table 3). Cape Crozier East and West were modelled separately.
Model Set / Key function / Number of cosine adjustment terms / Stratification or Covariate / Number of parameters / Log(Likelihood) / ΔAICc / Model weight / Uninformative parameterBird North original / Half-normal / 1 / — / 2 / -678.18 / 0.00 / 0.36 / —
Half-normal / 1 / Year covariate / 3 / -677.81 / 1.34 / — / Year
Hazard-rate / 0 / Year covariate / 3 / -677.84 / 1.40 / 0.18 / —
Hazard-rate / 0 / — / 2 / -679.08 / 1.81 / 0.14 / —
Half-normal / 0 / — / 1 / -680.22 / 2.04 / 0.13 / —
Hazard-rate / 0 / Stratified by Year / 4 / -677.64 / 3.14 / 0.07 / —
Half-normal / 0 / Year covariate / 2 / -679.79 / 3.23 / — / Year
Half-normal / 0 / Stratified by Year / 2 / -679.80 / 3.28 / 0.07 / —
Hazard-rate / 1 / Year covariate / 4 / -677.75 / 3.31 / — / Cosine adjustment
Hazard-rate / 1 / — / 3 / -679.08 / 3.89 / 0.05 / —
Bird North new / Half-normal / 0 / — / 1 / -833.12 / 0.00 / 0.55 / —
Half-normal / 1 / — / 2 / -832.60 / 1.00 / — / Cosine adjustment
Hazard-rate / 0 / — / 2 / -833.03 / 1.85 / 0.22 / —
Half-normal / 0 / Year covariate / 2 / -833.11 / 2.01 / — / Year
Half-normal / 0 / Stratified by Year / 2 / -833.12 / 2.07 / 0.20 / —
Hazard-rate / 1 / — / 3 / -832.11 / 2.08 / — / Cosine adjustment
Hazard-rate / 0 / Stratified by Year / 4 / -832.98 / 5.95 / 0.03 / —
Hazard-rate / 0 / Year covariate / 3 / -835.59 / 9.05 / 0.01 / —
Bird Middle / Half-normal / 0 / Survey covariate / 4 / -736.67 / 0.00 / 0.40 / —
Hazard-rate / 0 / Survey covariate / 5 / -736.04 / 0.86 / 0.26 / —
Half-normal / 0 / Year covariate / 3 / -738.90 / 2.34 / 0.12 / —
Hazard-rate / 0 / Year covariate / 4 / -738.06 / 2.77 / 0.10 / —
Hazard-rate / 0 / — / 2 / -740.43 / 3.34 / 0.08 / —
Half-normal / 0 / — / 1 / -742.00 / 4.42 / 0.04 / —
Bird South original / Half-normal / 0 / — / 1 / -799.70 / 0.00 / 0.57 / —
Half-normal / 1 / — / 2 / -799.63 / 1.90 / — / Cosine adjustment
Half-normal / 0 / Year covariate / 2 / -799.66 / 1.97 / — / Year
Half-normal / 0 / Stratified by Year / 2 / -799.68 / 2.02 / 0.21 / —
Hazard-rate / 1 / — / 3 / -799.20 / 3.11 / 0.12 / —
Hazard-rate / 0 / — / 2 / -800.46 / 3.57 / 0.10 / —
Bird South new / Half-normal / 0 / — / 1 / -726.13 / 0.00 / 0.48 / —
Hazard-rate / 0 / — / 2 / -725.65 / 1.08 / 0.28 / —
Half-normal / 0 / Year covariate / 2 / -726.09 / 1.97 / — / Year
Half-normal / 1 / — / 2 / -726.12 / 2.02 / — / Cosine adjustment
Half-normal / 0 / Stratified by Year / 2 / -726.13 / 2.07 / 0.17 / —
Hazard-rate / 1 / — / 3 / -725.49 / 2.83 / — / Cosine adjustment
Half-normal / 1 / Year covariate / 3 / -726.06 / 3.97 / — / Year
Hazard-rate / 0 / Year covariate / 3 / -726.09 / 4.03 / 0.06 / —
Cape Crozier West / Hazard-rate / 0 / — / 2 / -2111.23 / 0.00 / 0.71 / —
Hazard-rate / 1 / — / 3 / -2111.23 / 2.02 / — / Cosine adjustment
Hazard-rate / 0 / Stratified by Year / 4 / -2110.70 / 3.00 / 0.16 / —
Half-normal / 1 / — / 2 / -2113.34 / 4.22 / 0.09 / —
Hazard-rate / 0 / Year covariate / 3 / -2112.85 / 5.27 / 0.05 / —
Half-normal / 1 / Year covariate / 3 / -2112.91 / 5.38 / — / Year covariate
Cape Crozier East / Half-normal / 0 / — / 1 / -1170.70 / 0.00 / 0.37 / —
Half-normal / 0 / Year covariate / 2 / -1170.07 / 0.77 / — / Year
Half-normal / 0 / Stratified by Year / 2 / -1170.13 / 0.90 / 0.24 / —
Half-normal / 1 / — / 2 / -1170.21 / 1.05 / — / Cosine adjustment
Hazard-rate / 0 / Stratified by Year / 4 / -1168.15 / 1.07 / 0.22 / —
Hazard-rate / 0 / — / 2 / -1170.73 / 2.09 / 0.13 / —
Hazard-rate / 1 / — / 3 / -1170.00 / 2.68 / — / Cosine adjustment
Hazard-rate / 0 / Year covariate / 3 / -1170.80 / 4.28 / 0.04 / —
Cape Royds / Half-normal / 0 / — / 1 / -66.45 / 0.00 / 0.72 / —
Hazard-rate / 0 / — / 2 / -66.10 / 1.86 / 0.28 / —
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Online resource 4. Estimated South Polar Skua breeding population sizes (breeding pairs based on numbers of nests), within 1,000 m of Adélie Penguin sub-colonies at 3 Cape Bird locations and at Cape Crozier and Cape Royds. Estimates are model-averages, with finite-population-corrected 95% CIs in parentheses. Breeding population size was not estimated for Cape Royds in 2011 because only a single nest was observed.
2011–12 / 2012–13 / 2013–14Location / Original transects / New transects
Cape Bird North / 276 (158–481) / 244 (140–425) / 191 (136–269) / 140 (99–196)
Cape Bird Middle / 54 (27–107) / 104 (53–205) / 100 (51–197) / 37 (19–73)
Cape Bird South / 253 (151–425) / 374 (223–626) / 215 (144–320) / 136 (91–203)
Cape Crozier (pooled estimate) / 1347 (969–1871) / 1099 (791–1526) / — / —
Cape Crozier West / 1045 (723–1510) / 826 (572–1194) / — / —
Cape Crozier East / 302 (149–610) / 272 (141–524) / — / —
Cape Royds / — / 45 (18–111) / — / —
Online resource 5.Adélie Penguin breeding population sizes on Ross Island in 2011–12, 2012–13 and 2013–14 (numbers of breeding pairs; Lyver etal. 2014, personal communication).
Location / 2011–12 / 2012–13 / 2013–14Cape Bird North / 42,860 / 50,701 / 45,572
Cape Bird Middle / 2,534 / 4,912 / 4,343
Cape Bird South / 14,481 / 20,083 / 16,764
Cape Crozier East / 27,786 / 30,147 / 29,800
Cape Crozier West / 233,585 / 242,193 / 250,987
Cape Royds / 2,887 / 3,083 / 2,944
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