"Through discussion with the primate team, Welfare Committee and veterinarians, the difficult decision to euthanise was made."
He said they do not know what caused her health to decline, but he hopes a post-mortem examination will provide answers.
Primate keeper Rowena Fraioli said the team is devastated.
"We all adored her, and her happy dance and beautiful vocalisations that greeted us mornings and evenings they will be so missed."
Sally was one of Hamilton Zoo's most recognisable residents and would often sit in her special spot at the bottom viewer by the window with a blanket, preferably pink because that was her favourite colour, enjoying the sun and engaging with visitors.
Rowena says: "She just loved people, children and older men particularly. She'd get extra excited if they had facial hair and would run over to see them."
Sally was born at Auckland Zoo but was rejected by her mother, a former tea-party chimp, shortly after her birth. She was handraised for her first two years, taken in by Auckland Zoo head primate keeper at the time, Richard Seccombe and his wife Georgie, who raised her alongside their own children.
Returning to Auckland Zoo, Sally formed a troop with her sister Suzie, Mike and Lucy and their sons Lucifer and Luka. In October 2004, the troop transferred to Hamilton Zoo. Sally thrived after spending time in the purpose-built habitat, learning chimp behaviour from the others and solidifying her place in the troop.
Plans are underway to acknowledge Sally's special place, the bottom viewer where she spent so much time, by renaming it "Sally's Window".
Dr Fleming says: "The memorable connections Sally has made with so many people over the years have been invaluable to her species, and it is her legacy. It is such a privilege to experience a moment with a beautiful spirit like Sally and these moments are what encourage people to understand the vital importance of conservation."
Chimpanzees in the wild have a life expectancy of about 30 to 40 years, although in zoos they can live up to 10 years longer.
Chimpanzees are listed as endangered on the IUCN Red List due to habitat destruction, hunting for bush meat and the illegal pet trade.
The zoo team said the best way for the public to honour Sally is to make a difference in the lives of her wild counterparts by buying products that feature the Forest Stewardship Council (FSC) logo to aid in the conservation of chimp habitats or to donate to the Jane Goodall Foundation which does amazing work to protect chimpanzees.
