Cradle robber

CHICAGO — First she thoroughly breached all sense of propriety among her penguin peers by stealing spouses, brawling with another female and seducing uninitiated adolescent males.

Now, separated from the rest of the Brookfield Zoo colony, Zurita has likely become the world’s first successful single-parent penguin, raising a chick fathered by a much younger companion who can’t be bothered to help out.

Her soap-opera story has delighted zookeepers who believe that in watching Zurita they have gleaned important insights into improving the husbandry and genetic diversity of captive Humboldt penguins.

Hatched in 1990 in the Vancouver Zoo, Zurita’s reputation was intact when she came to Brookfield at age 6.

The zoo’s bird curator, Patty McGill — also coordinator of the Humboldt penguin species survival plan for North America — decided that a Brookfield, Ill., male penguin named Zorro was a good genetic match for her.

They were destined for a long period of domestic bliss, as penguins mate for life in a 50-50 partnership.

A female penguin carrying a fertilized egg lets her mate know, and he dutifully brings her small, smooth rocks to build a nest. After she lays the egg, the male takes equal turns sitting on it, keeping it warm during 42 days of incubation and allowing the mother to leave the nest to eat, stretch and preen. When the chick hatches, mother and father trade off finding food and coming back to regurgitate it down baby’s open beak.

After the chick grows up and leaves, Mom and Pop stay together, continuing the reproductive cycle.

“Female penguins remain faithful to their mates throughout their lives,” said Darlene Broniewicz, a senior keeper at the zoo’s Living Coast exhibit. “Male penguins cheat and go off with unattached females sometimes, but they always return to their mates and their nests.”

That was the pattern of Zurita and Zorro’s life together, but when Zorro died of kidney failure in 2000, they had never produced a fertile egg.

With Zorro gone and no available male in the colony, Zurita began looking for love in the wrong places, by soliciting males already spoken for.

One ended up giving her a fertile egg, but when keepers discovered the male was Zurita’s cousin, they took the egg away to avoid the dangers of inbreeding. Still, Zurita continued to look for male conquests.

“She continued to solicit males from established pairs,” Broniewicz said.

When she approached a male named Popero, his mate, Bumblebee, confronted Zurita in a violent tussle.

Penguins have sharp beaks and a strong bite, and the two females went after each other’s faces, trying to cut each other and pounding away with their powerful wing flippers.

To end the mayhem, keepers last winter put Zurita in a room of her own, off view from visitors.

“Penguins are very social animals, so we couldn’t leave Zurita alone,” McGill said. Instead, they brought in a year-old male, Gazpacho, to keep her company.

Male penguins aren’t thought to be capable of fertilizing an egg until they are about 3, so nobody expected Gazpacho to be able to fertilize her eggs. But late in November, when Gazpacho was just 15 months old, Zurita suddenly stopped eating, a pretty good sign that a fertile egg was on the way.

The keepers provided a pile of stones for Gazpacho to take to Zurita. He ignored the rocks, so Zurita gathered them herself and fashioned a nest, where she soon laid two eggs.

As she began incubation, she at times left the eggs, Broniewicz said, as though inviting Gazpacho to take a turn sitting on them. Whenever she stood up, however, he expressed interest only in making whoopee.

“He liked the first part of making babies but was far less interested in the second part of tending to the eggs and the hatched chicks,” McGill said.

Zurita ended up sitting on the eggs for the entire 42-day incubation, fed by the keepers and rising only momentarily to stretch and get a drink of water.

Keepers knew Zurita could not physically care for two hatched chicks alone, raising the specter that neither would survive. So they removed the second egg.

Sure enough, when the remaining egg hatched, Gazpacho again ignored his duty.

“He is the youngest male on record in any zoo anywhere to have successfully fertilized an egg,” Broniewicz said, “but he is just too immature to take up real parenting duties.

“He had free access to Zurita and the chick, but most of the time he wanted to be off playing with his friends, the other juveniles in the colony,” stopping off at the nest only to see if Zurita was in a mating mood.

Without help with feeding the chick, Zurita began losing weight. She was normally fed three times a day, but keepers increased it to five so both she and the chick would get sufficient nutrition.

It worked, delighting keepers.

“We don’t know of any other penguin anywhere that has been able to raise a chick on its own, without help from a spouse,” Broniewicz said.

In the wild, an incubating egg or helpless chick would become lunch for a predator as soon as the surviving parent moved off for a few minutes to find food.

“We could have taken the chick away a couple of times a day to give it supplemental feeding, but we wanted to minimize human contact with it, so that it wouldn’t imprint on us,” Broniewicz said.

“We proved it could be done, so that goes into the literature. It will give us and other zoos some direction in the future if one mate should die, leaving the other to raise a chick alone.”

There are 280 Humboldt penguins in 13 North American zoos, which use them to tell the story of how human infringement has reduced the wild population along 2,000 miles of South American coastline from a million 100 years ago to 40,000 today.

Brookfield has been instrumental in the zoo network organizing an annual wild census in an effort to protect the remaining birds. It also sponsors, with the Philadelphia and St. Louis zoos, a Humboldt penguin protected reserve in Peru, staffed with guards and a biologist.

Turning 100 days old Tuesday, Zurita’s still unnamed chick can now feed by itself. Keepers will soon put her and Zurita back with the colony, giving the chick access for the first time to a big, 20-foot pool.

The chick already knows how to swim, but barely, Broniewicz said.

“As she got a little older, we put a little children’s wading pool filled about a foot deep with water in with her and her mother. She watched her mother float around, but at first she couldn’t get the hang of it. She just waded upright, frantically flailing her flippers.”

Once the chick learned to float, keepers gave them access to a larger, 3-foot-deep pool so she could master swimming.

“It will be fun watching her go into the big pool the first time. She”s never seen a fish before,” said Broniewicz, noting that the 20-foot-deep pool is well stocked.

Once she experiences the deep pool, any dependency on Zurita will be gone. She will be on her own, playing with her still juvenile father and his pals, Ceviche, Salsa and Margarita.

Life also should calm down for Zurita soon, as McGill has found her a permanent home at the Milwaukee County Zoo, where a single male penguin awaits her. Within the next couple of months, she should be back to a life of marital bliss.