That Bird Blog – Bird Care and History for Pet Birds

In Part I of this article we examined the pros and cons of imprinting  – the process wherein an animal comes to see adults of another species as its natural parents – as regards birds in zoos, the pet trade and conservation programs.  Today I’d like to relate a few more of my experiences with imprinting as it related to the conservation of endangered birds and mammals.

Andean and California Condor Reintroductions

Rare birds raised for use in future release/re-stocking programs present a unique set of challenges.  Many are needed, and so pulling eggs to stimulate a second clutch is desirable.  However, birds raised by hand or under foster parents of another species face poor prospects for survival in the wild.

I have worked with both Andean and California condor chicks that were destined for future release into natural habitats.  These magnificent raptors are quick to imprint upon the people who feed them, so a novel solution was devised.  Keepers assigned to hand-feed condor chicks worked from behind a curtain, and presented food in the beak of hand puppet which closely resembled the head of an adult condor.  I’m happy to report that many hand-reared condors of both species successfully made the transition from captive to free-living existence.

Cows as Surrogate Mothers for Rare Species

Certain endangered mammals with which I’ve worked have presented particularly difficult dilemmas.  Gaur (rare wild cattle native to India and Southeast Asia) for example, breed readily in captivity but produce only 1 calf every 3-4 years.  In order to bolster this species’ numbers, captive female gaurs are sometimes chemically induced to produce several eggs instead of the usual single egg.

The extra eggs are implanted into domestic cows, which then give birth to and successfully raise baby gaurs.  However, cow-raised gaurs are not accepted by parent-raised gaurs.  Gaurs that are raised among domestic cows do not acquire normal gaur behaviors (i.e. appropriate reactions to dominant animals) and are attacked when integrated into gaur herds.  They rarely breed, and hence do not contribute to the species’ survival prospects.

Gorillas

Captive-born female gorillas are often unable to raise their own young, lacking examples and mentors in the form of older females, as would be the case in the wild (some zoos have tried “training films, to no avail!).  Hence many must be hand-raised (please see photo), but these too are often ostracized by other gorillas and rarely reproduce.

Further Reading

You can read more about the California condor reintroduction program at http://www.bigsurcalifornia.org/condors.html.

In 1935 Austrian zoologist Konrad Lorenz published a ground-breaking paper describing how goslings that he raised came to regard him as, in essence, their “parent”.  Further work on this process, soon to be known as imprinting, led to the founding of the science of ethology, the study of animal behavior.

As every bird-keeper knows, chicks taken from the nest and hand-raised make the best pets.  Such birds are said to be imprinted upon people, and they relate very well to us. However, there are some other uses for and sides to imprinting.  Today I’d like to relate some of my experiences with an assortment of imprinted creatures.

I Like Mice, but….

My oddest bird story involves a great horned owl.  Irresistibly cute in its efforts to threaten me, the owlet had been found in a Bronx park and was being harassed by some children (amazingly, these huge owls still survive in NYC, where they dine upon rats, muskrats, roosting pigeons and cats).  I and my coworkers raised the owl, a male, and he became a favorite at classes and on visits to homes for the elderly.

When he matured, however, the owl developed the distressing habit of trying to jam a mouse into the mouth of any passing person, much as he would feed a potential mate under more usual circumstances.  Interestingly, the owl never tried to stuff the mouse into one’s ear…he knew what a mouth was, even though the objects of his affection lacked a hooked beak (or any beak!).

Foster Parents

The owl showed no interest in members of his own species, which brings me to a major problem where imprinted endangered species are concerned.  In zoo based conservation programs, we sometimes pull the eggs of endangered birds so as to stimulate the female to lay a second clutch.  The pulled eggs are often put under a brooding “foster mother” of a related species, and the chicks therefore become imprinted on bird species other than their own.  This has worked well for peregrine falcons fostered beneath prairie falcon hens, and for Mauritius pink pigeons, which are fostered under ring doves.

However, rare finches raised by zebra or society finches often pick up the songs of their foster parents, and prefer the foster species over their own species as mates.  As you can imagine, this seriously hampers efforts to increase the population of the endangered birds.

Further Reading

The future of the magnificent pink pigeon was first championed by conservation legend Gerard Durrell.  Read more at http://www.durrell.org/Animals/Birds/Mauritius-Pink-Pigeon/.