Zoo keeper is surrogate parent to owl

January 20, 1992|By David Michael Ettlin

A spectacled owl that hatched in an incubator last week from a damaged egg is being reared by a surrogate parent -- a keeper at the Baltimore Zoo.

The owl species is rarer in captivity than in the wild -- at least for the present. Wildlife experts are keeping a wary eye on the bird's natural rain forest habitat, which has been shrinking due to human incursion.

In Guatemala, where the natural population of spectacled owls was threatened, captive birds were reintroduced to the wild, zoo officials said.

Baltimore Zoo officials say their new chick's survival is a small but important step in assuring species survival through a genetically diverse pool of captive birds.

Senior keeper Steven J. Sarro, who has been watching over and hand-feeding the owl around the clock since its hatching Jan. 12, describes the species as "uncommon" in captivity. Perhaps 30 are on display in the United States, he says.

Mr. Sarro is hoping to take charge of creating a "studbook" for the spectacled owl that will identify the lineage of captive birds -- much like the records kept by horse and dog breeders -- and help avoid inbreeding among the limited numbers available.

This chick is a good example of the increasing cooperation among zoos to improve species conservation, involving efforts by zoo officials in Columbia, S.C., Baltimore and Salisbury to bring the captive-bred parents and other owl pairs together.

The father is on breeding loan from the Salisbury Zoo, which in turn received another pair from Baltimore to display. The mother was hatched at Riverbanks Zoo in Columbia, S.C., fathered by a male owl on loan from Riverbanks.

Baltimore Zoo officials say the chick is important genetically because it may be the first of the species representing a third generation bred in captivity -- a distinction that is still in doubt and under research on the father's side.

The drama of the fragile chick's creation took place in the parent owls' heated kiosk along the Baltimore Zoo's old Main Valley early last month. Although the birds are "cavity nesters," Mr. Sarro said, the mother laid her egg atop, rather than inside, the nesting box.

Because the top of the box was not cushioned, the egg was cracked and zoo officials, fearing for the chances of a successful hatching, removed it to try artificial incubation.

A "dummy egg" replaced the real thing. Keepers hoped for another swap involving the chick if it ever hatched. But the parents rejected the ersatz egg a week later, and when the chick was born, its survival depended on Mr. Sarro.

Fortunately, he won't have to mother the bird for long. Spectacled owls reach a full adult size of about 1 3/4 pounds in a mere six weeks. The chick has been enjoying six feedings a day of defrosted mouse parts rolled in vitamins, and often exceeds Mr. Sarro's goal of a daily 10 percent gain in body weight.

At six weeks, however, the bird will not have the appearance of a full-grown adult. It will have juvenile plumage of a white head with black markings; the adult bird has a reverse appearance of black head with white markings.

Mr. Sarro said the chick likely will not imprint the memory of him as its momma, and to assure a minimal relationship, he intends to discontinue hand feedings as soon as it can pick up mousy meals that are dropped into the cage.

"I'm also looking into the possibility of making a hand puppet so when I feed him, he not only sees a human but a spectacled owl face."

The chick likely will reach sexual maturity at 4 years -- the age of its somewhat inexperienced parents -- and has an expected life span of more than 30 years, Mr. Sarro said.

"We were expecting a second egg," Mr. Sarro said, since spectacled owls generally lay two eggs per clutch, "and it didn't show up. The young bird -- she just didn't lay a second egg.

"We found an eggshell last year we believe was from her, just a shell. What we think is she laid it, didn't know what to do with it, and it just fell and broke. The instincts are there, but experience has a lot to play.

"This time she knew she should nest on something. It's just experience. This chick, if she had kept it, would have been a learning experience for both of them. It's very similar to mothering behavior for primates. It's pretty much instinct, but there is some learning."

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