During the austral winter, adult female southern right whales Eubalaena australis enter the South African coastal
waters to give birth and raise their young. Most births take place over a 4-month period, when the females
congregate in specific coastal areas or nursery grounds for up to a recorded maximum of 105 days. At this
time, the density of cow–calf pairs in nursery areas can reach as high as 3.2 pairs/km2 over 26 km of coastline.
Although a single young is born and suckled exclusively for 7 months to a year, recent observations on nursery
grounds include 3 incidents where apparently abandoned/orphaned calves-of-the-year have been seen associating
with a minimum of 2–3 different cow–calf pairs over periods of 11–38 days. Attempts to suckle from these
females have been noted in 2 of the cases, with the response of the female varying from extreme avoidance to
apparent tolerance. In one instance where the observations of the same trio extended over 21 days, the nonoffspring
appeared to compete at least equally with the offspring, even though the mother directed her evasive
tactics more at the non-offspring than her own calf. At the same time, both of the calves exhibited some growth
in length when compared with the size of the adult female: their subsequent survival is unknown. Non-offspring
nursing in monotocous species is generally rare, and the costs to the female potentially high: this is certainly the
case for seasonally feeding mysticetes such as the right whale, where the costs of lactation cannot be recovered
until the cow resumes feeding about 4 months after parturition. Hence, it is perhaps not surprising that these are
the first recorded observations of contemporaneous nursing attempts by offspring and non-offspring calves of
any mysticete.
