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Birth and Care of Young
A. Births at Zoological Facilities.
1. On September 26, 1985 at SeaWorld Orlando, a killer whale gave birth to a female calf, the very first killer whale successfully born and raised in a zoological environment.
2. Baby Shamu thrived in her environment and eventually reached adulthood herself. On February 2, 1993, at SeaWorld San Antonio, she gave birth to the first second-generation killer whale calf. The calf's mother -- the very first killer whale born at SeaWorld -- had her second calf on June 17, 1995 and her third on June 22, 1999.
3. SeaWorld has the largest killer whale breeding program of any park. To date, 13 calves have been successfully born at SeaWorld Orlando, San Diego, and San Antonio.
4. Other successful zoological park births have occurred at Sealand
of the Pacific (British Columbia), Marineland of Canada (Niagara Falls), Kamogawa Sea
World (Japan), and Marineland of Antibes (France).
Killer whale calves are born either tail-first or head-first.
B. Gestation.
The gestation period of a killer whale is about 17 months -- the longest known of all cetaceans. Pregnancies followed at the SeaWorld Adventure Parks have ranged from 15 to 18 months.
C. Birth seasons.
1. In the Pacific Northwest calving is thought to be bi-modally seasonal, with most births occurring in the spring and fall.
2. In other areas of the world, researchers have seen calves born throughout the year with no statistical evidence for birth seasons.
D. Frequency of births.
1. Based on limited data collected from populations at sea and in zoological facilities, a female may bear a calf every three to five years, although a decade may pass before some have another successful birth.
2. As with most marine mammals, usually only one calf is born at a time. Two occurrences of surviving twins have been documented in the wild.
E. Calving.
1. Calves are born in the water. The majority of deliveries seen by humans have been tail-first births, although a head-first birth has been observed. The umbilical cord snaps during delivery.
2. The placenta is discharged 8 to 15 hours postpartum, and one recovered at SeaWorld weighed 15.6 kg (34.4 lb.).
F. Calves at birth.
1. Size estimates of SeaWorld-born killer whales suggest that calves average 2.6 m (8.5 ft.) in length and weigh between 136 to 181 kg (300-400 lbs.).
2. The light areas of some young killer whales may be creamy white to pale orange rather than white. The color usually turns white within one year, although there are reports of some killer whales in the Antarctic which retain this yellowish color into adulthood.
3. In the first few days after birth, the dorsal fin and tail flukes are flexible and pliable, but gradually stiffen.
G. Care of the young.
1. While most maternal behavior is probably instinctive, first-time mothers are inexperienced at nursing their calves. At SeaWorld and in the wild, first-time mothers may learn how to nurse their young by observing this behavior from other mother whales.
2. Nursing.
a. When nursing, the calf suckles from nipples concealed in abdominal mammary slits.
b. Killer whale calves observed at SeaWorld began nursing several hours after birth. First successful nursing attempts ranged from 2.6 to 28 hours after birth.
c. Calves nurse below water, close to the surface. The mother glides in a horizontal position with her tail arched, and the calf swims on its side with its mouth on the right or left mammary gland.
To nurse, a calf swims on its side and suckles from nipples concealed in abdominal mammary slits.
d. Calves nurse about 5 to 10 seconds at a time, several times an hour, 24 hours a day. Nursing frequency peaks the first day or two following birth, at about 90 minutes total nursing. Thereafter, frequency decreases dramatically to 10 minutes per day or less, as the calf becomes more adept at nursing and obtains more milk at each feeding.e. The mother's milk is very rich so that the calf rapidly develops a thick, insulating layer of blubber. The milk fat content fluctuates as the calf develops, ranging from about 48% milk fat at the beginning of the nursing period and gradually decreasing to approximately 28% in the months that follow.
f. A calf may nurse for 12 months or more. A calf may essentially be weaned at one year of age but may continue to nurse occasionally for several more months.
H. Calf development.
1. A killer whale calf's upper teeth erupt at about two or three months.
a. On the average, the lower teeth emerge at four months. Studies at zoological parks show that calves begin to accept a few fish at about two or three months. They eat solid food consistently at about four months, which coincides with the emergence of the lower teeth.
b. By the age of one year, calves at SeaWorld eat 23 to 27 kg (50-60 lb.) of herring, smelt, and squid per day.
2. The average growth rate of the calves in the first year was 10 cm
(4 in.) per month. They were approximately 3.2 m (10.5 ft.) at
one year of age and had gained 454 kg (1,000 lb.).
3. A calf begins to swim independently of its mother within days of its birth, although the mother stays close to her calf and attentively directs its movements. The baby swims close to its mother and can be carried in the mother's 'slip stream', a type of hydrodynamic wake that develops as the mother swims. This helps the baby swim with much less energy and keep up with the pod.
4. Scientists at the Hubbs-Sea World Research Institute (HSWRI) study vocal development in killer whale calves.
a. Vocal behavior appears not to be genetically predetermined. Calves learn during the course of development which calls to make and under what circumstances.
b. Calves are most likely to develop calls like those of their mother. Vocal development studies at SeaWorld have determined that calves learn repertories of calls selectively from their mothers, though other killer whales may be present and vocalize more frequently.
c. A calf can vocalize within days of birth, but sound production is shaped with age. A calf's first vocalizations are 'screams' -- loud, high pitched calls that bear no resemblance to adult-type calls.
d. At about two months, a calf produces its first pulsed calls with similarities to adult-type calls. From that point until puberty, a calf's vocal repertoire continues to expand.
