The female killer whale comes in heat many times in a single year. Hence, mating can occur at any given time. However, it is more common during summers. On the other hand, in the North Atlantic, breeding occurs primarily between October and November, while in the western part of North Pacific, breeding occurs mainly between the months of May and July.

Once mating takes places, the female killer whale has a gestation period of around 17 months and then gives birth to live calf. Based on the available scientific data, females generally give birth to a calf once every 5 years. The birth takes place in the water, with either the tail or the head emerging first. The umbilical cord breaks either during the delivery or immediately after the calf is born.

At birth, the lighter colored parts of the calf can some times be lemony yellow or creamy white in color, but as the calf grows older, the parts become white. Also, it takes a couple of days after birth for the dorsal fins and the tail fins to become hard and stiff.

As killer whales are mammals, the mother feeds the calf with milk through nipples that are hidden in mammary slits present in the abdominal region. It takes a few hours after birth for the calf to begin nursing. While nursing takes place in water, it occurs just below the surface. While feeding the calf, the female killer whale assumes a horizontal position to make it easy for the calf to get to the mammary glands. At a given moment, a calf can drink milk for just five to ten minutes, but it feeds several times in a single day. The killer whale's milk is rich in proteins and fat, and this enables the calf to develop a thick layer of fat called blubber in no time. As the calf grows, the fat present in the milk also increases. The calf nurses for around 12 months after it is born.

As a mother, the killer whale is an attentive and caring one. She watches her calf carefully. It is common to see the calf swimming in the female's slip stream, which is a type pf hydro-dynamic stream created by the female while she is swimming. This way the calf does not have to expend too much energy when it swims.

Much of the information on how a killer whale calf develops is learned from observing calves living in marine parks. A calf gets its upper teeth when it is around 2 to 3 months old, while the lower teeth appear when it is about 3 to 4 months old. By the time the lower teeth appear, the calf begins to eat some fish, but it actually begins to eat solid foods regularly when it around 5 months old. By the time the calf becomes a year old, it has the ability to consume fifty to sixty pounds of smelt, squids and herring each day. In the first year of its life, a calf grows around 2.6 feet, and in the second year around 2.2 feet. While a calf is able to make some sounds a few days after being born, actual sounds to communicate take some time and develop as the calf gets older. Calves learn to make sounds from their mothers.

According to the studies carried out researchers in zoological parks, female killer whales get sexually mature after they attain a length of 4.6 to 4.9 meters, which happens between 6 and 10 years. On the other hand, male killer whales get sexually mature after they reach a length of 5.5 to 6.1 meters, which occurs between the ages of 10 years and 13 years.

More Articles :

• Are Killer Whales Endangered ?
• Killer Whales Anatomy
• Life Cycle Of A Killer Whale
• Scientific Name For Killer Whale
• What Do Killer Whales Eat ?
• What Eats Killer Whales ?

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