Male humpback whales favor enormous females

February 14th, 2009 - 3:12 pm ICT by ANI  

Washington, Feb 14 (ANI): A new study has found that male humpback whales favor the largest females.

Female humpback whales are usually larger than males to begin with, measuring up to around 50 feet long and weighing approximately 79,000 pounds.

While obesity is understandably a serious problem in humans, it is interesting to find that in some of the largest animals ever to exist, bigger is indeed better. Thus size does matter! lead author Adam Pack, an assistant professor of psychology and biology at the University of Hawaii at Hilo, told Discovery News.

Pack, who is also the co-founder and vice president of The Dolphin Institute, and his research team made the determination after studying courting humpback whales for five consecutive years in the waters of the Auau, Kalohi and Pailolo channels off West Maui.

In winter and spring months, the whales assemble on shallow banks and along coastal areas for breeding and calving.

Since females produce a single calf every two to three years on average, and not all females migrate to breeding grounds, males usually far outnumber females at the sites.

Interested males serve as escorts for their female of choice, swimming in close proximity to her and, if present, her calf.

The males all gravitated to the largest females, sometimes engaging in dangerous fights to win and maintain the coveted escort position.

The principal escorts defensive behaviors include visual displays, such as lunging through the water with ventral throat grooves expanded, making the whale look visually larger, to screens of bubbles expelled from the blowhole or mouth, to chases and physical strikes, sometimes drawing blood from a rival, Pack explained.

The researchers next measured each whale using both a hand-held sonar device and mathematical calculations based on angle of view and distance.

The scientists even donned snorkeler gear and swam around, and underneath, the courting whales.

Fitness appears to be behind the whales fondness for fat and long bodies, since the researchers also discovered that the largest females also produced the biggest calves.

Since whales depend upon stored body fat to support their metabolic requirements, particularly during the winter, the extra heft is necessary for their survival, promoting greater reproductive success and aiding females in the nursing of their offspring. (ANI)

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