Additional Information and Interpretations
Breeding Success and Population Control:
After experiencing phenomenal success with breeding chimpanzee at the zoo (one of the most successful zoo’s in the world at that time), there appears to have been an attempt to restrict breeding/control numbers around the mid 1960s - several chimpanzees were exported around this time, including 2.2 to Melbourne Zoo in 1966.
Breena produced her first offspring, a female named Dorne, at the age of 8 in 1962; followed by the birth of her second offspring, a female named Stella, at the age of 11 in 1965. While Stella was sent to Adelaide Zoo in 1968; Breena and Dorne remained at the zoo until their deaths in 1974. What is curious here is that in the 9 years between the birth of her last offspring and her death, Breena never produced anymore offspring; while her daughter, Dorne, died at the age of 12 having never produced offspring (female chimpanzees are usually capable of reproducing by the age of 8).
My guess is that mother and daughter, Breena and Dorne, were kept separately from the other chimpanzees in a pair from the mid 1960s onwards, to prevent overpopulation. It would not have been possible to separate Molly and her offspring from the group with this intention in mind as she had produced two sons (and would have bred with them), so Molly and her eldest son, then aged 6, were exported to Melbourne Zoo in 1966.
Causes of Death:
I don’t have information for the cause of death of any of these chimpanzees, but the dates may offer some clues. Breena and her daughter, Dorne, died within 3 days of each other in late June/early July. This is the coldest time of year in New Zealand, so it’s possible they died of pneumonia - a common cause of mortality in captive chimpanzees. This also feeds into my theory that Breena and Dorne were kept separately in a pair from the other chimpanzees during this time. Since no other chimpanzees at the zoo died around this time, it could suggest something affected their cage that didn’t affect the other cages i.e. their cage was more exposed to the elements; one of them caught a virus that was isolated in their cage and didn’t infect the other group/groups etc.
The cause of Yoka’s death is more obvious as she died the same day she gave birth to male twins, her ninth and tenth offspring. It’s almost certain she died as a result of complications from the birth, which also claimed the life of one of the twins; the other was hand raised and died 6 weeks later.
Influence of Tea-parties on Reproduction and Parenting:
Wellington Zoo held chimpanzee tea parties until 1970. The original performers were Yoka, Molly and Breena, with their offspring replacing them as they grew older and proved difficult to control. While the first offspring of these females were mother raised, they were taken away by keepers for training and participation in the tea-parties for periods of time from a young age. With the babies returned to their mothers after an hour or so, and the mothers trusting the keepers they had formed a bond with; it’s not hard to imagine the mothers actually enjoyed being given a break.
Yoka’s reproductive history may have been influenced by this. It’s interesting to note how short the birth intervals are between her first five offspring (born between 1960 and 1970). The birth interval for chimpanzees is typically 3-5 years. All Yoka’s birth intervals during this time were less than 3 years (in some cases closer to 2 years). Perhaps the weaning of each offspring was aided by the additional nutrition they would have received through the tea-parties? Yoka’s fifth offspring, Pan, was born at the end of 1970 (the year the tea-parties ended) and was solely mother raised. The age gap between his birth and Yoka’s next offspring was almost 4 years. After raising her next offspring, Jagger, who was exported before his second birthday; Yoka rejected her next offspring, Jodie and Jessie, and they were hand raised. Maybe Yoka thought motherhood was too much work, after receiving ‘help’ with her first few infants (apologies for my anthropomorphism here).
Yoka’s Legacy:
Yoka’s line is well represented in the region to this day. As well as her daughter, Jessie (born in 1978); her grandsons, Boyd (born to Bebe in 1978), Marty (born to Bebe in 1987) and Gombe (born to Jodie in 1993) are still alive today. Boyd and Marty have each sired many offspring; as did Yoka’s deceased grandson Snowy (born to Bebe in 1983), who has many descendants from his offspring born at Taronga Zoo during the 1990s.
Name Meanings:
Names of chimpanzee infants: Pat was named after St. Patrick, the patron saint of Ireland, as he was born on St. Patrick’s Day; Bebe is a Swahili name meaning ‘baby’; Pan was named after the Latin name for his species Pan troglodytes; Jagger was named after Mick Jagger; Yoka’s last offspring all have ‘J’ names: Jagger, Jodie, Jessie and Jimmy.
