|The journey south to the Antarctic can be the most vulnerable stage of the migration for the humpback whales. Although many of the calves are growing fat and strong, the adults are in a poorer condition because they have eaten little or nothing since leaving Antarctica and have used their reserves of body fat.
Needing to feed as soon as possible, it is now the newly pregnant females who lead the migratory procession, followed by the young males and females, then the mature adults and resting females, with the mothers and calves now bringing up the rear.
ABOVE: A clear sign that body weight is low is a sharply protruding spine as seen in this young adult whale in Hervey Bay in 1998 .
(Photo: Trish Franklin)