Tuesday, March 31, 2009

Display Rocks and TN Penguins

Display Rocks Are Getting Tennessee Aquarium's Penguins Excited

By Thom Benson

Chattanooga, TN - Lately when senior aviculturist Amy Graves brings the big bowl of iced-down capelin into Penguins’ Rock, she notices a few of the birds are interested in something more than fish. "Some of the macaronis like Hercules will take the ice cubes out of the pan and try to build a nest with them," Graves said. "And there’s been more calling and swinging of heads lately." It is apparent that at least some of the Tennessee Aquarium’s penguins are ready for romance.

April marks the beginning of the breeding season for gentoos and macaronis. These cold-climate birds get seasonal cues from the changing light cycle throughout the year. The longer daylight hours during spring bring out the amorous behavior shown by Hercules and other penguins at the Aquarium.

Last year was the first time nesting materials were given to these penguins. Many of them were inexperienced, younger birds and others may have not have fully adjusted to the switch to the Northern Hemisphere light cycle. "We’re a little more hopeful that we’ll see eggs and potentially see chicks this year versus last year," said Loribeth Aldrich, one of the Aquarium’s aviculturists. "This year all of the birds appear to be on the same page biologically after having gone through a complete molt together.”

This year there may be more magic in the "magic rocks" because of something one of the penguin keepers noted on a recent Aquarium trip to Antarctica. "We went to five different gentoo rookeries and they all had different nests," said Kevin Calhoon, the Aquarium’s assistant curator of forests. "Many of the nests had jagged rocks that were actually piled quite high." So rather than use the smooth river rocks that were placed in the exhibit last year, Aquarium staffers went to a local quarry to collect nearly 1,000 pounds of limestone rocks. "We chose these rocks because they look more like what the penguins have in the wild," reports Aldrich. "These rocks are a little more angular and we’re hoping that these will stack together a lot better and the penguins will be able to build their nests up higher."

These new rocks will be introduced to the exhibit on April 1st and according to Graves, no stone will go unturned when love is in the air. "It will immediately stimulate a breeding response," said Graves. "The birds will instantly start selecting rocks, carrying them to their nesting spots and even squabbling over the best rocks as pair bonding begins."

The rocks will stay on exhibit through most of the summer. While some signs point to successful courtship this season, many factors can affect breeding success. Eggs may or may not be fertile, first-time parents might not have fully developed paternal instincts and newborn chicks must defy high infant mortality rates.

Even though future sighting of penguin babies is uncertain, Tennessee Aquarium visitors will be treated to lots of activity and drama between the penguin pairs over the upcoming months. "It’s a lot of fun," said Calhoon. "You’ll see the penguins carrying the rocks around in their mouth like a dog with a ball. You’ll see them fighting over a rock that seems to have a higher value than the rest and stealing rocks from each other. And there are all kinds of calling and sounds to go with a very visual experience."

Penguin Breeding Information:
As nesting material, small rocks are added to the exhibit that acts as a marker for the beginning of breeding season. The act of building a nest encourages a strong bond between the male and female penguins. End results of successful nest building are large flattened piles of carefully chosen rocks.

Once paired, the penguins will further strengthen their bond by:
Macaroni penguins will do lots of mutual preening and vocalizing in conjunction with head swinging and wing flapping.
Gentoo penguins will be more conservative with their displays. They stand next to each other and vocalize with necks stretched tall.
Egg incubation: Macaroni – 33-39 days. Gentoo – 36-41 days
Both penguin species lay two eggs approximately 4 days apart. Penguin chicks hatch without help from parents. It usually takes 24-48 hours for a chick to fully hatch.
Both penguins share in parental responsibilities by taking turns on the nest keeping the chick warm and regurgitating food as needed. Parents sit on the chick for approximately 15 days until the chick is able to maintain its own body heat. Chicks remain at or around nest until fledging. Penguins fledge (or become independent from parents) between 65-75 days.

Watch the penguins on the Tennessee Aquarium’s live webcam at: www.tnaqua.org.

The Tennessee Aquarium inspires wonder and appreciation for the natural world. Admission is $21.95 per adult and $14.95 per child, ages 3-12. Each ticket purchased helps support Aquarium conservation programs. The IMAX® 3D Theater is next door to the Aquarium. Ticket prices are $8.50 per adult and $6.00 per child. Aquarium/IMAX combo tickets are $27.95 for adults and $19.95 for children. Excursions aboard the new River Gorge Explorer depart daily into “Tennessee’s Grand Canyon.” Cruise tickets are $29.00 per adult and $21.50 per child (3-12). Advance tickets may be purchased online at www.tnaqua.org or by phone at 1-800-262-0695. The Aquarium, located on the banks of the Tennessee River in Chattanooga, is a non-profit organization. Open every day except Thanksgiving and Christmas, the Aquarium and IMAX are accessible to people with disabilities.

Story and image courtesy of Zoo and Aquarium Visitor @

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