Denver Zoo Helps Orangutan Mother With New Infant

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A Denver Zoo Sumatran orangutan infant is back with her mother after a rocky start. Hesty (Hess-tee), a female and the first of her species born at the zoo in 25 years, is doing fine with her mother thanks to the dedicated efforts of the zoo’s primate care team. Zookeepers and veterinary staff needed to place the infant in an incubator 11 days after birth. After receiving critical care, she’s now doing well with mom. Although not on public view yet, the zoo is thrilled with Hesty's progress behind the scenes.

Hesty, the orangutan is now back with her mother behind the scenes at Denver Zoo.

We prepared extensively for this birth. Nias is an amazing animal, and is so intelligent. However, with this being her first infant, we weren’t sure she would know exactly what to do

A Denver Zoo Sumatran orangutan infant is back with her mother after a rocky start. Hesty (Hess-tee), a female and the first of her species born at the zoo in 25 years, is doing fine with her mother thanks to the dedicated efforts of the zoo’s primate care team. Zookeepers and veterinary staff needed to place the infant in an incubator 11 days after birth. After receiving critical care, she’s now doing well with mom behind the scenes at the zoo.

“It’s important for young orangutans to bond with their mothers and learn the skills to raise their own offspring in the future. In our planning, we brainstormed solutions for every possible scenario we could come up with that would ensure the infant’s wellbeing and keep her with her mother,” says Area Supervisor Ronda Schwetz.

Hesty was born to mother, Nias (Nee-us), and father, Mias (Mee-us), on June 19. She is only the fourth birth of this species at the zoo and the first since 1985. Orangutans are tiny at birth, weighing three to four pounds and are completely dependent upon their mothers.

Although initially Hesty seemed to be doing fine, staff could not tell for sure if she was nursing regularly and on June 22, the infant appeared weak. Denver Zoo veterinarians sedated Nias to exam her and Hesty. During the examination veterinarians discovered Hesty was significantly dehydrated and placed her in the proper nursing position. Hesty ingested about 70 milliliters of breast milk and weighed 3.67 pounds at the end of her feeding.

“After the exam, we tried to help Hesty locate mom’s nipple through operant conditioning training. Nias also let us feed the infant formula through the mesh in her enclosure. We planned to assist Nias and Hesty in this manner until she could nurse on her own. However unfortunately she took a turn for the worse,” Schwetz said.

On the morning of July 1, staff found Hesty nearly unresponsive. Veterinary staff examined her immediately, finding she was dehydrated and unable to maintain her body temperature.

“We moved her into an incubator next to her mother’s quarters and bottle fed her. We made sure Hesty and Nias could see each other the entire time. Nias remained interested in the infant while we provided critical care,” Senior Veterinarian Dr. Felicia Knightly said.

Over the next 18 days, Hesty nearly doubled her body weight from 2.86 pounds to 4.4 pounds under the care of veterinarians and zookeepers. Nias responded well when staff was able to reunite the two on July 19. However, Hesty still didn’t immediately know how to nurse. Staff sedated Nias on July 23 to teach her how to find Nias’s breast and ensure she could nurse on her own. Fortunately this time, the training appears to be successful as Hesty has begun nursing on her own.

Staff continues to be ready to assist Nias by providing supplemental formula to Hesty if necessary.
“Hesty is so important to us and her species. We will continue to do everything possible to ensure her wellbeing. We’re watching her very closely and taking it day by day, but we’re pleased with her progress so far,” says Schwetz.

Planning for this infant began months ago with consistent monitoring of the pregnancy, consultations with neonatologists and regular ultrasounds of the fetus. Zoo staff worked with Nias to train her to present her abdomen for inspection and to receive ultrasounds through a hole in the mesh of her enclosure. An exceptionally intelligent animal, staff was able to monitor Nias’s successful progress.

“We prepared extensively for this birth. Nias is an amazing animal, and is so intelligent. However, with this being her first infant, we weren’t sure she would know exactly what to do,” Schwetz said.

Training with Nias was extensive and focused on ways to help her know how to properly hold her infant and to allow zookeepers to closely examine the infant and provide supplemental feedings through the mesh of the maternity enclosure, if necessary.

Mias, Hesty’s father, was born in 1983 at Toronto Zoo and arrived at Denver Zoo in 1997. Nias was born in 1988 at San Diego Zoo and came to Denver Zoo from El Paso Zoo on a breeding loan in 2005. The two were paired together under recommendation of the Association of Zoos and Aquariums’ (AZA) Species Survival Plan (SSP®) which ensures healthy populations and genetic diversity among zoo animals. Fortunately, the couple has proved to be an excellent match.

Orangutan means “person of the forest” in Malay and the species is among the closest relatives to humans. Physically they are known for their stout bodies, long arms and shaggy, red hair. The orangutans at Denver Zoo can often be seen showing off their arboreal talents, swinging from ropes and trees in their expansive habitats.

Sumatran orangutans are only found on the island of Sumatra in Indonesia. In the wild, they are critically endangered due to habitat loss stemming from logging, mining and forest fires. Also, the practice of killing a mother to secure an infant or juvenile for the live animal trade is a common practice. Currently there only about 6,000 left in the wild.

Chronology of Events after Hesty’s Birth

  •     June 19: Hesty born at 4:55 p.m. Hesty appeared strong and mother was attentive.
  •     June 20: Staff monitoring Nias and Hesty 24 hours a day. Staff is unable to confirm nursing. However infant is believed to have nursed over the night.
  •     June 21: Hesty and Nias pass the 72-hour critical period, which supports belief Hesty is nursing at night. Zoo staff ends 24-hour watch, to allow Hesty and Nias rest time during the night. Staff continues to monitor the pair during the day.
  •     June 22: Hesty appeared in a weakened state. Nias is sedated and both she and Hesty are examined. Hesty was placed on Nias in proper nursing position and successfully nurses.
  •     June 23: Hesty appears alert during a recheck, but seems unable to find her mother’s nipple.
  •     June 24: Hesty is fed formula and Pedialyte as zookeepers attempt to teach her through operant conditioning how to nurse. She remains strong during day, but appears tired in the evening.
  •     June 25-30: Hesty continues supplemental feeding program. Appears strong most days, but often tired toward evening.
  •     July 1: Hesty is found unresponsive. Nias is sedated to examine Hesty. Hesty is found dehydrated and unable to maintain her body temperature due to low blood sugar. She is placed in an incubator. Zookeepers feed her every three hours around the clock. During feedings staff wears a vest of synthetic fur material that Hesty clings to, simulating the experience she would have with her mother. Hesty remains within eyesight of her mother and father, while staff cares for her 24 hours a day.
  •     July 4: Hesty seems much stronger, grabbing onto her bottle and pulls it closer.
  •     July 5-18: Hesty makes steady progress. Slowly doubles her weight to 4.4 pounds.
  •     July 19: Hesty is reunited with her mother at 9:30 a.m. Nias picked up Hesty and cradled her immediately. Staff continues to monitor pair 24 hours a day.
  •     July 19-22: Staff continues with little success to attempt to guide Hesty to mom’s breast. Staff is successfully supplementing feeding Hesty with formula.
  •     July 23: Nias is sedated. Staff places Hesty on Nias’s right breast. Staff offers the artificial nipple used in bottle feedings to Hesty. Once her sucking reflex is spurred, staff transitions Hesty to Nias’s nipple. Hesty successfully nurses. Staff then repositions Hesty on Nias’s left side to see if she could locate Nias’s left nipple on her own. She found the left nipple and nursed on her own. Both Hesty and Nias appeared well during vet exam.
  •     July 24: Hesty nurses on her own!
  •     July 25 – 28: Hesty continues to nurse on her own throughout the day and into the night. Staff continues to monitor Hesty and Nias 24 hours a day.

Staff Background:
Primate Area Supervisor Ronda Schwetz: Ronda came to Denver Zoo in 2005 and has 18 years of animal care experience. Aside from her duties at Denver Zoo she supports primate conservation efforts in Africa and Asia. She recently returned from trips to Sumatra and Borneo where, along with other Denver Zoo staff, she supported centers that care for orangutans displaced by illegal pet trade or fires. Zoo staff provided medical supplies, enrichment devices to physically and mentally stimulate the orangutans and tools and expertise to fix broken facilities. In September, Schwetz has planned the Orangutan SSP Workshop at Denver Zoo where orangutan professionals from North American zoos will share the most up-to-date information regarding the care and management of the orangutans in zoos.

Denver Zoo Senior Veterinarian Dr. Felicia Knightly: Dr. Felicia Knightly has been with Denver Zoo since 1997 and was named senior veterinarian in April 2009. Knightly manages all hospital operations and oversees the veterinary care of the Zoo’s 3,500 animals. She has wide-ranging experience in animal care and has made multiple trips to Madagascar to research the conservation of lemurs. She assisted Dr. Edward Louis of Omaha’s Henry Doorly Zoo on the Madagascar Biodiversity and Biogeography Project and Dr. Randy Junge on the Prosimian Biomedical Survey, a study of various lemur species. Recently Dr. Knightly assisted the Tasikoki Rescue Centre in Sulawesi, Indonesia with critically-needed veterinary care.

About Denver Zoo: Denver Zoo is home to 3,800 animals representing more than 650 species and is accredited by the Association of Zoos and Aquariums (AZA). AZA accreditation assures the highest standards of animal care. Denver Zoo’s mission is to secure a better world for animals through human understanding. Since 1994, Denver Zoo has participated in 526 conservation projects in 55 countries. In 2009 alone, Denver Zoo participated in 80 projects in 22 countries and 4 continents and more than $1 million in funds was spent by the zoo in support of animal conservation in the field.

A leader in environmental action, Denver Zoo is dedicated to ensuring the safety of the environment in support of all species and is the first U.S. zoo to receive ISO 14001 certification for the entire facility and operations. This international certification ensures the zoo is attaining the highest environmental standards.

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