CHICAGO (CBS) — Brookfield Zoo received a belated Christmas gift, closing 2017 with a zoo birth.

A gray seal pup was born Dec. 26 at Brookfield Zoo, the third pup for mother, 13-year-old Lily and sire, 13-year-old Boone.

seal 6 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

A male gray seal pup with his mother, 13-year-old Lily at Brookfield Zoo. The pup was born on December 26, 2017, and will remain behind the scenes until late February. (Credit: Jim Schulz/Chicago Zoological Society)

The male pup weighed 36 pounds at birth and is on track to quadruple his weight by the time he is weaned at 3 weeks of age, according to the zoo.

“The fat-rich milk he receives from his mother, allows the pup to put on a lot of weight in a short amount of time. Gray seals have one of the shortest nursing periods of pinnipeds (group of marine mammals that are winged- or web-footed),” the zoo said in a statement.

The pup is currently behind the scenes nursing, learning how to swim, and bonding with his mother.

seal 2 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

A male gray seal was born at Brookfield Zoo on December 26, 2017. Gray seal pups are born with long, white fur called lanugo, which is molted in two to four weeks and replaced with shorter, stiffer hair similar to that of adults. Animal care staff estimate he will be able to venture into his outdoor habitat at Pinniped Point in late February. (Credit: Jim Schulz/Chicago Zoological Society)

“The pup’s birth is very important to the gray seal population in North American institutions accredited by the Association of Zoos and Aquariums. Although their numbers are not threatened in the wild (they are found in the Western North Atlantic, the Eastern North Atlantic, and the Baltic Sea), currently there are only 25 individuals in 10 institutions. Brookfield Zoo is home to five individuals,” the zoo said.

Although guests will most likely not be able to see the pup at the outdoor habitat at Pinniped Point prior to the pup molting – when the pup replaces his long, white fur with shorter, stiffer hair – they can view updated photos and video of him on the zoo’s website at CZS.org/GraySealPup or on Brookfield Zoo’s Facebook page.

Here’s a peak at the pup:

seal 7 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

(Credit: Jim Schulz/Chicago Zoological Society)

seal 1 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

(Credit: Jim Schulz/Chicago Zoological Society)

seal 4 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

(Credit: Jim Schulz/Chicago Zoological Society)

seal 5 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

(Credit: Jim Schulz/Chicago Zoological Society)

seal 3 PHOTOS: Brookfield Zoo Welcomes Gray Seal Pup

A male gray seal pup with his mother, 13-year-old Lily at Brookfield Zoo. The pup was born on December 26, 2017, and will remain behind the scenes until late February. (Credit: Jim Schulz/Chicago Zoological Society)

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