Birth & Care of Young - Dolphins

GESTATION

1. The gestation period is about 12 months. Bottlenose dolphin calves are born after a gestation of about 12 months.

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BIRTH SEASONS

1. Worldwide, calves are born throughout the year. 2. Seasonal calving peaks vary by area. • Dolphin births off the coast of Sarasota, Florida occur in late spring to early summer. A secondary peak occurs in early autumn. • In waters along the central U.S. Atlantic coast, the prolonged calving season shows a spring peak. • In Patagonia and South Africa, births peak in summer. • Most dolphin births along coastal Texas waters occur in March. • Peak calving for dolphins in Florida's Indian River Lagoon occurs in April and August. • Bottlenose dolphins in the Pacific Ocean along the coast of Southern California have shown a calving peak in the fall.

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FREQUENCY OF BIRTH

1. A female dolphin can potentially bear a calf every two years, but calving intervals generally average three years.

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CALVING

1. Calves are born in the water. Deliveries are usually tail-first, but head-first deliveries are also seen. The umbilical cord snaps during delivery. Dolphin calves are born in the water usually tail first. 2. Sometimes an assisting dolphin may stay close to the new mother and calf. Although this assisting dolphin often is referred to as an "auntie" dolphin, it may be male or female. This auntie dolphin is often the only other dolphin a mother allows near her calf.

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CALF AT BIRTH

1. Calves are approximately 100 to 135 cm (39–53 in.) long and weigh about 10 to 20 kg (22–44 lb.). 2. In the first few days after birth, the calf’s dorsal fin and tail flukes are pliable and lack firmness, but gradually stiffen. 3. Calves, darker than adults, show several vertical, light lines on their sides, a result of fetal folding. These lines disappear within six months. Dolphin calves are usually darker in color than the adults.

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CARE OF THE YOUNG

1. Nursing. • Calves nurse below water, close to the surface. • The calf suckles from nipples concealed in abdominal mammary slits. • Observations in zoological parks show that nursing usually begins within six hours of birth. A calf nurses as often as four times per hour for the first four to eight days. • Each nursing instance usually lasts only about five to ten seconds. A calf nurses three to eight times per hour throughout the day and night. • Milk is composed of 33% fat, 6.8% protein, and 58% water, with traces of lactose. The rich milk helps the baby rapidly develop a thick blubber layer. • A calf may nurse for up to 18 months. 2. In caring for her calf, a mother dolphin stays close by and attentively directs the calf's movements. The calf is carried in the mother's "slip stream," the hydrodynamic wake that develops as the mother swims. This helps the baby swim and enables the mother and calf to stay up with the group. This dolphin calf is being carried along in its mother's "slip stream". 3. There is probably a considerable amount of learning involved in mothering.

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CALF DEVELOPMENT

1. Bottlenose dolphin breeding colonies in marine zoological parks continue to provide a unique opportunity to observe and quantify dolphin reproductive biology. Valuable information has been learned about dolphins by studying them in marine zoological parks like SeaWorld. 2. In zoological environments, calves begin to take a few fish at about three to four months, when their teeth begin to erupt. Calves begin to eat fish when they reach about 130 to 150 cm (51–59 in.). 3. Within a few days of birth a calf can vocalize, but signature characteristics develop with age. 4. Mother-calf bonds are long-lasting; a calf typically stays with its mother three to six years.