Abstract:
Site fidelity is common among migratory cetaceans, including humpback whales (Megaptera novaeangliae). In the Northern
Hemisphere it has been found that fidelity to humpback whale feeding grounds is transferred maternally but this has never
been shown for the species in the Southern Hemisphere. We examined this in a unique feeding area off west South Africa
using resighting data of 68 individually identified humpback whales by means of photographic (tail flukes and dorsal fins)
and/or molecular methods (microsatellite genotyping) over an 18 year span. We found short-term association patterns and
recurrent visits typical of other feeding grounds. Males and females had different seasonality of attendance. Significant
female-dominated presence corresponded to timing of an expected influx of females on their southward migration from
the breeding ground: firstly non-nursing (possibly pregnant) females in mid-spring, and mothers and calves in mid-to late
summer. The potential benefit of this mid-latitude feeding area for females is illustrated by a record of a cow with known
age of at least 23 years that produced calves in three consecutive years, each of which survived to at least six months of age:
the first record of successful post-partum ovulation for this species in the Southern Hemisphere. We recorded association of
a weaned calf with its mother, and a recurring association between a non-lactating female and male over more than two
years. Moreover, three animals first identified as calves returned to the same area in subsequent years, sometimes on the
same day as their mothers. This, together with numerous Parent-Offspring relations detected genetically among and
between resighted and non-resighted whales is strongly suggestive of maternally derived site fidelity at a small spatial scale
by a small sub-population of humpback whales.
