  A substantial period of life after reproduction ends, known as
postreproductive lifespan (PRLS), is at odds with classical life history
theory. Prolonged PRLS has been confirmed in only two non-human mammals, both
odontocete cetaceans. We investigate the evidence for PRLS in a third species,
the false killer whale, Pseudorca crassidens, using a quantitative measure of
PRLS and morphological evidence from reproductive tissue. We examined specimens
from false killer whales from combined strandings (South Africa, 1981) and
harvest (Japan 1979-80) and found morphological evidence of changes in the
activity of the ovaries in relation to age. Ovulation had ceased in 50% of
whales over 45 years, and all whales over 55 years old had ovaries classified
as postreproductive. We also calculated a measure of PRLS, known as
postreproductive representation (PrR) as an indication of the effect of
inter-population demographic variability. PrR for the combined sample was 0.14,
whereas the mean of the simulated distribution for PrR under the null
hypothesis of no PRLS was 0.02. The 99th percentile of the simulated
distribution was 0.08 and no simulated value exceeded 0.13. These results
suggest that PrR was convincingly different from the measures simulated under
the null hypothesis. We found morphological and statistical evidence for PRLS
in South African and Japanese pods of false killer whales, suggesting that this
species is the third non-human mammal in which this phenomenon has been
demonstrated in wild populations. Our estimates for PrR in false killer whales
(0.12-0.37) spanned the single values available for the short-finned pilot
whale (0.28) and the killer whale (0.22) and are comparable to estimates for
historical or hunter-gather human populations (0.3-0.47).
