Fig 1.
Location of the 112 samples collected from 78 females in Svalbard.
Female polar bears were captured in 2012 and 2013. Each circle represents a polar bear sampled for blood and adipose tissue. The three regions are represented by different colors: North-West (orange dots), North-East/South-West diagonal (blue dots) and South-East (grey dots).
Table 1.
Model selection using the AICc to determine the most parsimonious model explaining variation in stable isotope and fatty acid principal component values of female polar bears sampled in Svalbard in 2012 and 2013.
Fig 2.
Ordination plots from fatty acids (FA) principal component analysis (PCA) scores grouped by (A) season and (B) breeding status. PCA was based on mass percentage of total dietary fatty acids (FAs) relative to FA 18:0, in female polar bears sampled in Svalbard in 2012–2013. The first and second axes explained 31.6% and 16.7% of the total variation, respectively. FA contribution to each axis appears on the left panel. On panels A and B, each dot represents an individual. Individuals with similar FA composition (PCA scores) are near each other and individuals with dissimilar FA composition are farther from each other, the center of the star linking all individuals of a same group represents the centroid of PCA scores for that group.
Fig 3.
Ordination plot from fatty acids (FA) principal component analysis (PCA) scores grouped by sampling area.
PCA was based on mass percentage of total dietary FAs relative to FA 18:0, in female polar bears sampled in Svalbard in 2012–2013. The second and third axes explained 16.7% and 12.7% of the total variation, respectively. See Fig 2 for the interpretation of an ordination plot.
Table 2.
Relationships between fatty acids’ PCA scores, environmental factors and breeding status in female polar bears.
Fig 4.
Median mass % of 33 fatty acids (FA) according to A) season, B) breeding status and C) sampling area. FA were obtained from adipose tissue. Sampling areas are North-West (NW), North-East/South-West diagonal (NESW) and South-East (SE). Breeding status indicates whereas the female was accompanied or not with cubs and their age: solitary females (Solitary), females with cubs of the year (with COYs) and females with yearlings (with YRLs). Female polar bears were sampled in Svalbard in 2012 and 2013. Bars are median values and standard errors.
Table 3.
Relationships between selected fatty acids (FA) and sampling area.
Fig 5.
Relationship between blood stable isotopes and (A) sampling area, (B) season and (C) breeding status. Nitrogen (δ15N) and carbon (δ13C) stable isotope values were measured in plasma (circles) and red blood cells (triangles). Seasons are spring (samples from April) and autumn (samples from September). Breeding status indicates whereas the female was accompanied or not with cubs and their age: solitary females (Solitary), females with cubs of the year (with COYs) and females with yearlings (with YRLs). We sampled female polar bears in Svalbard in 2012 and 2013. Circles/triangles represent medians and bars standard error.
Table 4.
Relationships between stable isotope values, environmental factors and breeding status in female polar bears.
Fig 6.
Summary of diet tracer variations according to sampling area.
Diet tracers include δ15N and δ13C values in plasma (e.g δ13CP) and red blood cells (e.g δ15NRBC), and fatty acids principal component first axis values (FA PC3). For each area, seasonal differences in plasma δ13C values appear as “δ13CP_Sp = δ13CP_Aut”, Sp denotes spring and Aut denotes autumn. Each sign (+ or -) denotes direction in significant differences. For example, δ15NRBC values are lower in North-West females compared to NESW females but not different from South-East females. Whereas FA PC3 values are higher in North-West females compared to NESW and South-East females. The red stars indicates the positions of whale carcasses, the orange star indicates the position of a bear feeding on a walrus (Odobenus rosmarus) kill, the green stars a bird cliff where bears have been observed feeding on birds and the blue star represents the position of a bear with reindeer hair between the teeth.
Fig 7.
Stable isotopes values measured in plasma of female polar bears observed feeding before capture.
Three females with COYs were observed feeding on seabirds (green dot), one female had reindeer hair between the teeth (blue dot), one was observed feeding on a walrus (orange dot), four on three different whale carcasses (red dot) and two on unidentified seals (grey dot).