Giraffes typically only give birth to one calf at a time. While twin births are possible, they are extremely rare in giraffe populations. In this article, we’ll take an in-depth look at giraffe reproduction and birth to understand why giraffes almost always have single births.
How Often Do Giraffes Give Birth?
On average, female giraffes give birth around every two years. The gestation period for giraffes is approximately 15 months, one of the longest among land mammals. After giving birth, female giraffes will not get pregnant again for at least another year as they nurse their calf. This long period between births is one reason why twin births are uncommon.
Giraffes have a prolonged gestation period compared to many other hoofed mammals like deer or cattle that give birth yearly. The extended pregnancy allows the calf to develop fully to its large size before being born. Newborn giraffes already weigh over 100 pounds and stand over 6 feet tall at birth.
Why Don’t Giraffes Have Twins?
While twin births can occur in giraffes, they are exceptionally rare. Less than 1% of giraffe births in the wild result in twins. There are a few key reasons why giraffes almost always have just one calf:
- The long gestation period of 15 months makes it harder for two fetuses to develop.
- Giraffes only release one egg during ovulation, meaning only one can be fertilized.
- The large size of newborn giraffes makes it difficult for the mother to support two calves.
- Twinning may reduce survival chances in the wild due to higher nutritional demands.
Carrying two large calves for over 15 months puts extra strain on the mother’s body. The single fetus alone grows to over 100 pounds by birth. Supporting two fetuses of this size would be extremely taxing and likely dangerous to the mother’s health.
Releasing just one egg at a time also reduces the chances of conceiving twins. While some animals regularly release multiple eggs, giraffes ovulate only one egg per cycle. This makes it impossible for two eggs to be fertilized, limiting births to just one calf.
Challenges of Twin Giraffe Births
The difficulties faced by mother giraffes during twin births help explain why they are so uncommon. Carrying and nourishing two fetuses for over 15 months uses up significant energy reserves. The strain of a twin pregnancy can result in health complications for the mother, including:
- Increased risk of anemia from higher nutritional demands
- Greater difficulty in moving and foraging with the extra weight
- Higher likelihood of complications during delivery
- Potential long-term impacts like prolapse or metabolic disorders
Once born, raising two calves simultaneously presents further challenges. Newborn giraffes already weigh over 100 pounds each. Nursing and caring for two calves of this size requires extra energy and nutrition. The milk production needed to feed twin calves may be difficult to sustain.
In the wild, a mother giraffe raising twins may struggle to find enough food and water for herself and both calves. The presence of two calves can also make the small family unit more conspicuous to predators looking for an easy meal.
Twin Giraffe Births in Zoos
While exceedingly rare in the wild, twin births do occasionally happen in zoos and wildlife parks. These facilities provide extra nutrition and medical care that may increase the chances of a twin pregnancy succeeding. However, zoos must still take special precautions when a mother giraffe is expecting twins.
To support the nutritional needs of a twin pregnancy, the mother’s diet is boosted starting early in the gestation period. Extra protein, calories, and nutrients promote the health of both fetuses. After birth, supplemental bottle feeding of one or both calves may be required if the mother struggles to produce enough milk.
Veterinary exams monitor the growth and health of the twin fetuses throughout pregnancy. If medical issues arise, zoos have procedures to sustain the pregnancy. These measures are not options for giraffes in the wild, which likely contributes to the rarity of successful twinning.
Hand-raising one of the calves is sometimes necessary to improve survival odds after twin giraffe births in captivity. This reduces the mother’s burden while still allowing the calves to grow up together.
Signs of Twin Pregnancy
In zoos or wildlife parks, warning signs during pregnancy can indicate a giraffe may be carrying twins. Keepers will monitor for the following clues:
- Rapid weight gain in early pregnancy suggests multiple fetuses.
- Visible enlargement of both sides of the abdomen rather than just one side.
- Signs of extra fetal movement detected during check-ups.
- Abnormal hormone levels associated with twin pregnancies.
Catching a twin pregnancy early allows time to provide special care for the mother. However, it can still be difficult to confirm twins until late in the pregnancy when both fetuses can be visualized during exams.
Twin Giraffe Calves After Birth
Raising twin calves comes with additional challenges after the birth. Giraffe mothers may struggle to nurse two calves, especially if it is their first birth. As a result, supplemental bottle feeding is often required for at least one of the twins.
If the mother is unable to support both calves, one of the twins may be raised by keepers. Hand-raised twins still often have contact and interactions with the mother and sibling. This helps promote natural social bonds despite the extra human assistance.
Twin giraffe calves typically meet all the same growth milestones as single calves, although they may mature a bit slower. Reaching full adult size and height takes over 4 years. For the first 16 months, the calves stay closely bonded with their mother for safety and nourishment.
As long as they receive adequate nutrition, twin giraffe calves can grow up healthy together. Their nearly identical genetics allows for a unique opportunity to study similarities versus differences in their development and behavior.
Survival Rates of Giraffe Twins
Studies on giraffe twin births in zoos have found significantly higher mortality rates compared to single calves. One analysis found a 54% first-year mortality rate for twin calves compared to just over 14% for single calves.
The increased mortality appears directly related to the challenges of a twin pregnancy and birth. Difficult deliveries and inadequate milk supply are common causes of death soon after the calves are born. Premature birth may also result in weaker calves with underdeveloped immune systems.
However, with intensive veterinary oversight and supplemental feeding, both twin calves can survive. Connecting the calves with other non-maternal adult giraffes for protection and companionship also improves their outcomes.
| Birth Type | First Year Mortality Rate |
|---|---|
| Single Calf | 14.3% |
| Twin Calves | 54% |
These higher mortality rates demonstrate why twinning is avoided in wild giraffe populations. The species’ biology strongly favors singleton births to promote calf and maternal health.
Famous Cases of Twin Giraffes
While rare, some remarkable cases of twin giraffes have been celebrated in zoos around the world. These high-profile twin births highlight the challenges and excitement around these unique events.
Kito and Kalumet
In 2000, Brookfield Zoo near Chicago welcomed twin giraffe calves. Kito and Kalumet were born to first-time mother Bakari after a standard 15-month pregnancy. The delivery went smoothly, but Bakari did not produce enough milk to support both calves.
Kito was left with Bakari to nurse, while Kalumet was hand-raised by keepers. Despite the supplemented feedings, the twins grew up healthily and eventually sired calves of their own.
Junior and Speedy
The San Antonio Zoo announced a rare set of twin giraffes in January 2020. While the pregnancy showed no signs of twins, mother Upesi gave birth first to Junior, followed unexpectedly by Speedy two hours later.
Speedy required intensive medical care after birth but recovered fully. The zoo has carefully monitored the calves’ development and milk intake to ensure both receive adequate nutrition.
Hope and Miracle
Denver Zoo welcomed newborn twins Hope and Miracle in 2020. Their mother Kipele was given regular ultrasounds during her 15-month pregnancy that revealed twins. After the challenging birth, the two calves overcame some early health scares.
Despite being small initially, Hope and Miracle gained strength and bonded with their mother thanks to supplemental bottle feedings. The twin calves progressed well alongside each other.
Conclusion
Giraffe mothers invest significant time and energy in raising large, single calves. Their biology preferentially supports singleton births after long gestation periods. While twinning does occasionally occur, the challenges often lead to higher mortality rates.
Zoos and parks can facilitate rare giraffe twin births with medical support and interventions. But in the wild, twins remain an unusual event. Giraffes almost exclusively give birth to just one calf at a time.
