Fig 1.
Migration, feeding grounds and breeding grounds of the Australian humpback whale populations.
Approximate feeding grounds of the D and E1 populations are the historical stock boundaries Area IV and V, as defined by the International Whaling Commission. Approximate breeding grounds are represented by the dotted areas, and migration routes are indicated by arrows.
Table 1.
Whales sampled for baleen isotope records.
Table 2.
Reported isotopic values for possible humpback whale prey items.
Fig 2.
Bivariate comparison of whale and prey isotope values corrected using two sets of TFs.
Each prey source is plotted twice depending on the set of TFs: rectangles a, c, and e represent the generic set of TFs: + 3.4‰ for δ15N and + 0.5‰ for δ13C, while rectangles b, d, and f represent the fin whale-specific set of TFs: +2.77‰ for δ15N and +2.26‰ for δ13C. Sources: Antarctic Krill (dashed line), Australian Krill (full line), average Australian fish species (dash-dot line). Each zone is therefore created using isotopic coordinates consistent with prey values and corrected for trophic fractionation. The whale isotope data should plot within the zone appropriate to the prey consumed by the individual.
Table 3.
Means, SD, minima/maxima for δ13C and δ15N for all whales.
Fig 3.
Isotope profiles for E1 population classical feeders.
Each horizontal zone is created using isotopic coordinates consistent with prey values and corrected for trophic fractionation. The whale isotope data plots within the zone appropriate to the prey consumed by the individual. Food zones: Antarctic Krill (dashed line), Australian Krill (full line), average Australian fish species (dotted line). Time flows from left to right.
Fig 4.
Isotope profiles for D population classical feeders.
Each horizontal zone is created using isotopic coordinates consistent with prey values and corrected for trophic fractionation. The whale isotope data plots within the zone appropriate to the prey consumed by the individual. Food zones: Antarctic Krill (dashed line), Australian Krill (full line), average Australian fish species (dotted line). Time flows from left to right.
Fig 5.
Isotope profiles of supplementary feeders from both populations.
Each horizontal zone is created using isotopic coordinates consistent with prey values and corrected for trophic fractionation. The whale isotope data plots within the zone appropriate to the prey consumed by the individual. Food zones: Antarctic Krill (dashed line), Australian Krill (full line), average Australian fish species (dotted line). Time flows from left to right.
Fig 6.
Isotope profiles for temperate zone feeders.
Each horizontal zone is created using isotopic coordinates consistent with prey values and corrected for trophic fractionation. The whale isotope data plots within the zone appropriate to the prey consumed by the individual. Food zones: Antarctic Krill (dashed line), Australian Krill (full line), average Australian fish species (dotted line). Time flows from left to right.
Fig 7.
Boxplot representation of each individual whale according to feeding category.
Representations of the spread of values for each individual baleen plate, with colours assigned as per feeding category. Boxes represent the 25th and 75th quartiles and are sectioned by the mean. Whiskers represent the 95th quartiles, with outliers as dots.
Table 4.
Scheffe comparison of means between the different feeding groups.