Chattanooga, Tenn. (April 1, 2024) – While other birds’ hearts might flutter at the thought of building nests with supple twigs, fluffy fibers, mud, or even their own saliva (yes, really), nothing gets the Tennessee Aquarium’s penguins quite as excited as rocks.
Big rocks. Little rocks. Smooth rocks. Rough rocks. Whatever type of rock a bird prefers, their arrival by the bucketful in the Penguins’ Rock gallery signals the official start of penguin nesting season and a flurry of activity that may — flippers crossed — lead to one or more tiny, fluffy chicks this summer.
“This is a very special day,” says Assistant Curator of Forests Loribeth Lee. “These guys have been ready for a couple of weeks as the lights are gradually changing, and the days are getting a little bit longer, so they’ve known that this was coming.”
Gentoo Penguin Bigfoot selects a rock for his nest during "Rock Day," which begins penguin nesting season at the Tennessee Aquarium.
Those steadily lengthening days, courtesy of the Aquarium’s team of systems operators, herald the arrival of spring and trigger biological signals telling the penguins that love is in the air. Nevertheless, it isn’t until the rocks are dumped into inviting piles that the Gentoo and Macaroni Penguins can get to work building the nests that will help protect their young
Rocks may seem like a poor choice for nesting material. However, in the wild, these are the only building supplies these species have available in the largely barren landscape of the Antarctic Peninsula and surrounding islands. While other, more northerly-dwelling penguin species use plant fibers or other cozier materials in their nests, Gentoos and Macaronis have adapted to make best use of the hard stuff.
The coming of Rock Day brings with it not only a palpable air of excitement but a dramatic intensity that is infectious to watch. Some long-standing mates will likely pair up again, while some birds may split off to seek new partners. As they build their nests, some penguins will demonstrate remarkable engineering skills, especially considering their lack of hands. In contrast, others will resort to outright thievery to snatch the “best” rocks from their neighbors.
Macaroni Penguin Hercules selects a rock for his nest during "Rock Day," which begins penguin nesting season at the Tennessee Aquarium.
Penguins at the Aquarium are included in the Association of Zoos and Aquariums’ Species Survival Plan, which tracks genetic records to ensure pairings produce genetically healthy offspring. By encouraging breeding between individuals whose DNA is not over-represented within the limited population of penguins in human care, the Plan safeguards the overall health and wellbeing of the entire species.
Through its participation in the SSP, the Tennessee Aquarium and other institutions ensure healthy colonies of penguins can inspire guests by serving as ambassadors for their species now and into the future.
“We have to be smart and responsible for these birds,” Lee says. “We want to keep our populations at zoos and aquariums genetically diverse so that we can think about their future 40 to 50 years down the road.”
The nesting season can end as early as July or as late as October, depending on when eggs are laid and whether penguin chicks are hatched. If a penguin pairing produces a fertile egg, it will take approximately 40 days for chicks to emerge.
Gentoo Penguin Carla selects a rock for her nest during Rock Day, which begins penguin nesting season at the Tennessee Aquarium.
From the Rock Day frenzy to the potential arrival of chicks in the coming months, penguin fans who want to follow along with the drama and excitement of nesting season can check in on the birds via the Aquarium’s live Penguins Rock webcam at tnaqua.org/live/penguins-rock/