Wednesday, January 7, 2015

African penguin chicks, part 2

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This is one of a series presented by the National Aviary, which works to inspire respect for nature through an appreciation of birds.

The National Aviary’s newest African penguin chicks are 3 weeks old today.

This is a very important milestone because, at this age in the wild, African penguin chicks’ social bond with their parents is fully developed: They can recognize their parents, and their parents can recognize them, even in a crowd of other penguins. Equally important, they have grown their next, thicker coat of down feathers and are physiologically capable of regulating their body temperature without continual brooding by one of their parents. The ability to maintain a stable body temperature even when their environment is very cold or very hot, a characteristic of all “warm-blooded” animals (mammals, birds, and, as we now know, even some dinosaur ancestors of birds), is called homeothermy.

Achieving homeothermy fosters greatly increased independence of the chicks; in turn, it frees both parents to leave the nest for longer periods and even at the same time. This is important because the increasing energy needs of the large but still growing chicks necessitates increased food intake, and two parents delivering food is better than one. In addition, the parents need to recoup their own energy reserves, which because of their continual care of the chicks, can be greatly depleted by this time.
The techn
ical terms used to describe the end points of this marked developmental transition for penguin chicks are “guard phase” and “post-guard phase.” During the guard phase, which is what thousands of people have been watching on the National Aviary’s penguin nest cam for the past few weeks, penguin chicks are continually brooded and protected by one or both parents. But, in the post-guard phase, when wild adult penguins leave their chicks alone for protracted periods, chicks must for the first time guard themselves against predators and from attacks by unrelated adult penguins.

In the wild, post-guard phase penguin chicks protect themselves by forming aggregations, sometimes called creches. For penguin species living in the very cold Antarctic region, these aggregations are not only important for protection from predators, but also for keeping warm. Keeping warm is not much of a challenge for African penguins, and research has shown that African penguin chicks form aggregations primarily to avoid aggression from adult penguins.

At this important stage of their development, the National Aviary’s two chicks do not have the opportunity to join an aggregation of other chicks, and they also lack the coordination to negotiate the rocks and cliffs in the exhibit. So, for their safety, they will be hand-reared until they are fully grown. This approach ensures they will quickly become full-sized members of the flock and also that they will be comfortable in their future roles as ambassadors for their species in the National Aviary's educational and interactive programs.

Beginning this weekend visitors to the National Aviary can see the newest penguin chicks in person. They will be on exhibit in the Avian Care Center window, newly remodeled (enlarged and lowered) so that even our littler “guard phase” visitors can easily get nose to beak with a penguin chick.


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