March of the Penguins: A King-sized Bundle of Joy

This month, the Detroit Zoological Society is bringing you not one, but three blog posts centered around our favorite flippered friends — the penguins who live at the Polk Penguin Conservation Center. The facility, which had been closed since 2019 due to waterproofing issues, reopened in February, and we can’t wait to share with you all the stories we have been saving over the past two and a half years.

The Detroit Zoo was very eager to welcome a king penguin chick who hatched in 2020. Even though we have raised many penguin chicks throughout the years, we haven’t raised a king penguin chick in 19 years, so this was truly a “king-sized bundle of joy!”

The rearing of this chick is also an interesting story. During courtship, king penguin pairs form a tight bond, which culminates with the laying of a single egg. Unexpectedly, this was not the case for the parents of this chick. Once the egg was laid, the pair was moved into the rookery with the egg. The rookery is an area within the penguin habitat that provides some separation and privacy while the pair incubates their egg and raises their chick. The female was immediately receptive to the male, lifting her brood patch and showing the male their precious egg. The male appeared receptive initially, but rather than soliciting the egg transfer, he quickly became aggressive towards the female.

Normally, the female will transfer the egg to the male shortly after it is laid, usually within 24 hours. Both will share incubation duties, with the male completing the larger share. We decided to give the male a fake egg for a couple of days, while the female incubated the real egg.  After several days, he proved to be a good egg incubator but was still aggressive towards the female. Once the egg was determined to be fertile, we gave it to the male but knew that we had to develop an alternate plan for rearing this chick. 

Fortunately, another pair whose egg was not fertile met the criteria for becoming foster parents. Egg fostering is a technique we have used in the past with other penguin species, either to give another pair the opportunity to rear a chick or when a pair is not able to rear a chick. The foster male (and the biological male) are actually the last of three king chicks to be reared here 19 years ago. Although the foster male had never raised a chick before, the foster female had raised a couple of chicks previously. In fact, she raised the biological “father” 19 years ago, and therefore is the “grandmother” of this chick!  We initially gave the foster pair a fake egg, and about halfway through the incubation period, we transferred the real egg from the biological male to the foster male.

The average incubation period for king penguin eggs is 54 days. On day 54, we noticed an empty eggshell on the ground near the parents – the chick had hatched! Since then, the male chick has fully grown and was given the name Archie. We love seeing this “royal” bird in the habitat and remembering the special foster story that made it possible.

Come visit Archie and watch this fabulous flock waddle, dive, swim and display other natural behaviors in the Polk Penguin Conservation Center.

Bonnie Van Dam is the curator of birds for the Detroit Zoological Society.

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