CHICAGO (CBS) — Spring is here, which means love is in the air – at least for the penguins at the Shedd Aquarium.

The penguins at the Shedd Aquarium are beginning to prepare for mating season by building nests.

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Spring marks the official time for nest building for the two species of penguins that reside at the Shedd Aquarium. Rockhopper and Magellanic penguins use sticks and rocks to build “love nests” before they pair up to begin mating season.

The aquarium’s animal care experts scatter twigs and stones throughout the penguin habitat, signalling the penguins that it is time to begin the weeks-long process of nest building. The ritual has been occurring since 1994 at the Shedd.

“The male penguins will pursue the perfect rock to attract a female mate, and the birds will build their nests in a variety of sizes,” according to the Shedd Aquarium.

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Check out the nest building photos below!

A Shedd Aquarium trainer lays out rocks the Magellanic and rockhopper penguins will use to create their nests ahead of mating season. During this time, the male penguins will search for the perfect stone to attract potential mates. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

A rockhopper penguin picks up a rock as nest building season begins at Shedd Aquarium. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

A Shedd Aquarium trainer scatters twigs and stones in the penguin habitat to signal the beginning of the weeks-long process of nest building. The birds will build their nests in a variety of sizes. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

Rockhopper penguins begin collecting and arranging nesting materials to create a love nest before they pair up for mating season. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

During the several weeks long process, the penguins will explore the exhibit searching for the best stone and sturdy sticks. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

As mating season begins at Shedd, sticks and rocks are provided to the rockhopper and Magellanic penguins to start the process of nest building. (Photo credit: ©Shedd Aquarium/Brenna Hernandez)

Eggs are expected by the end of April into May. Guests may or may not be able to spot them, as the penguins typically sit on their nests to keep the eggs warm.

The Shedd’s breeding program has been successful with several new additions in recent years, including Rockhopper penguins Ruggles, in 2014, and Diego, in 2015.

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Video credit: ©Shedd Aquarium/Sam Cejtin