March 25--It turns out humans aren't the only ones who use a big rock to seal the deal.
Instead of diamonds, male penguins scour their turf for rocks to attract the opposite sex, a ritual that will unfold at Shedd Aquarium over the new few weeks with the arrival of the mating season. As part of their courtship activities, the Shedd's rockhopper and Magellanic penguins build a love nest with plastic twigs and stones -- materials aquarium staff began scattering around the penguin habitat this week in anticipation.
The shiniest rock might not even get the girl. Christy Sterling, the Shedd's supervisor of penguins and otters, said she doesn't know why penguins choose the rocks they do. "Maybe how good your nest looks might attract your mate," she said.
After the penguins peruse the nesting materials, the male penguins start the heavy lifting, she said. The hardworking males go back and forth with rocks and sticks -- and sometimes they fall victim to a crafty next-door neighbor who will steal some of the supplies when the penguin is away, she said. "We've seen some sneakiness," Sterling said.
Eggs come on the scene at the end of April and into May, but visitors shouldn't expect to spot them. The aquatic birds are vigilant about sitting on the nests to keep the eggs warm -- and that keeps them out of sight, according to the Shedd.
The love connection can be fleeting for some, while other penguins are more faithful. Magellanic penguins are monogamous, but the rockhoppers are known to stay paired up for a season or two before moving on to new partners, Sterling said.
The breeding ritual has expanded the Shedd's penguin family in recent years: Ruggles arrived in 2013 and chick No. 23 hatched last year, according to the aquarium. More than 30 penguins live at the Shedd.
lvivanco@tribpub.com
