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Zebra Finch, Taeniopygia guttata, Nutrition – the role of carotenoids and testosterone

Zebra Finch

While we are all aware of the importance of good nutrition to our pets, it is interesting to see just how complex this topic can be. Keeping this in mind will, I hope, prevent us from becoming lazy when it comes to feeding even relatively hardy birds such as the zebra finch.

As in most animals, male zebra finches utilize the hormone testosterone to help develop secondary sexual characteristics, such as their bright red bills. However, this comes at a cost, as testosterone has also been shown to weaken the immune system.

Carotenoids – compounds that impart yellow and orange colors to carrots and other foods – also help male finches to maintain their bright colors and, as a consequence, to attract females. The finches obtain carotenoids from their diet.

Recently, researchers at Arizona State University have shown that, in addition to imparting color, carotenoids also combat the negative influences of testosterone in zebra finches. Males deficient in carotenoids suffer depressed immune systems, while those with a sufficient intake benefit from testosterone by becoming more attractive to female finches.

This information reinforces the importance of a providing our birds with a well-balanced diet, and may have implications for human health as well. I suggest feeding your zebra finches a variety of nutritious foods, including such important basics as Goldenfeast Australian Blend Bird Food / Tropic Fruit Pudding and ZuPreem Fruit Blend, to assure a sufficient intake of carotenoids and other nutrients.


Interesting research concerning the effect of diet on zebra finch reproduction is posted at:

Mate Choice in the Budgerigar (Parakeet), Melopsittacus undulatus – opposites do not attract


Research conducted recently at University of California (Irvine) has revealed that female budgerigars choose males whose contact calls closely resemble their own. Males, in turn, pay more attention to similarly-sounding mates than to females whose calls differ from theirs, grooming them often and defending them vigorously. When paired with such females, male budgerigars also devote substantially more time to the care of their young. This extra care translates into an increased rate of growth and survival for the nestlings.

It has long been known that male budgerigars imitate the calls of their mates, and that doing so seems to strengthen the bond between the pair. Budgerigars have highly variable contact calls, more so than many other parrots. This may help the pair to maintain contact and to thwart competition within the huge flocks that parakeets typically form. The current research is the first to show that female mate choice is influenced by the initial sound of the male’s contact call, before he has begun to imitate her sounds.

Although budgerigars breed readily for pet keepers, this information may have important implications for hobbyists and zoos working with rare parrots that do not reproduce reliably in captivity.


An interesting article on the natural and captive history of the budgerigar is posted at:

European Starlings, Sturnus vulgaris, Can Determine When People are Watching – and React Accordingly

European Starling
Researchers at the University of Bristol determined this month (May, 2008) that starlings and other birds moved away from feeders if watched by people, but continued feeding if the observers remained just as close to the feeders, but turned their eyes away.

Interesting….but I think bird keepers have known this to be true for quite some time. Most of us learned early on that parrots focus on our eyes when watching us, and that the best way to sneak up on a bird that is reluctant to return to its cage is to observe it by quick, side-wise glances. This is a good point to keep in mind when watching newly acquired finches and other shy pets.

In fact, a key to being able to get a good look at the birds I worked with in large zoo exhibits was to avoid a direct stare. Birds feeding calmly not far from me would immediately fly off if I shifted my glance, even if the rest of my body remained immobile. I had first learned this lesson in the wonderful book Hand Taming Wild Birds at the Feeder, by Alfred G. Martin (Bond Wheelwright Co., 1963), and was subsequently able to induce a variety of birds to feed from my hand.

I have a bit of eviBarn Owldence that birds “know” the meaning of other human facial features as well. I once helped to raise a barn owl, Tyto alba, that had been found on a Bronx street (yes, a surprising number of birds do live there!). The bird imprinted on people (came to view us as its “parents”), which suited it well for us in educational programs. As hand-raised birds will do, this male owl sought a human “mate” when it matured. In typical barn owl fashion, it would bring any nearby keeper a mouse – perching on our shoulders and trying to stuff its lovely nuptial gift into our mouths! Never once did the owl try an ear or eye – it seemed to be able to make, in its brain, the quite large transition from bird beak to human mouth.


The Ringdove (Barbary Dove, Ringed Turtle Dove, Java Dove), Streptopelia risoria – a common pet helps to save the endangered Pink Pigeon

Few birds actually live up to the reputations we assign them – owls, for example, have been shown to be less “wise” than most other species when it comes to learning from their mistakes. The ringdove, however, does indeed seem to possess the calm, peaceful demeanor that we have come to associate with doves (although those I kept as a boy begun their admittedly “soft” cooing at 4 AM, rendering my otherwise patient mother far from “calm”!). Kept in a mixed species aviary, even breeding pairs of ringdoves are quite tolerant of smaller birds.

When I began work at the Bronx Zoo, a primary focus of the Ornithology Department was the conservation of the pink pigeon, Nesoenas mayeri. Limited in distribution to the island of Mauritius, off the east coast of Africa, this spectacularly colored bird is highly endangered. It is here that the ringdove’s “accepting nature” came into play. Pigeons and doves feed their young with “crop milk”, a food partially formed from the lining of the mother bird’s crop. Commercial substitutes exist, but none approach the real thing.

In order to obtain as many eggs as possible from the small captive population, we pulled eggs from incubating female pink pigeons and placed them beneath brooding ringdoves (egg removal, within a specific time period, stimulates the female to lay another clutch). The female ringdoves were wonderful foster parents. They produced amazing quantities of crop milk to feed their unusual nestlings, which grew to almost twice the size of their foster moms before fledging. I shall not soon forget the sight of a female ringdove literally perched on the back of a huge nestling pink pigeon while feeding it! Birds raised by foster parents of other species often have problems in breeding with their own species when they mature – fortunately, the fostered pigeons went on to reproduce normally.

The ringdove makes a fine pet and is available in a wide variety of colors, including apricot, white and pied. It has an unusual captive history, and may actually be a mere variant of the wild African collared dove, S.roseogrisea, which was domesticated 2-3,000 years ago. Its actual status is unclear, however, as captives have likely hybridized with related species, such as the Eurasian collared dove and the red-eyed dove. Feral populations of ringdoves live in the USA (Florida, Los Angeles, San Francisco), Italy, Taiwan and England, usually to the delight of local residents.

An interesting perspective on the origins of the ringdove is provided at: http://www.internationaldovesociety.com/Articles/ringneck%20history.htm

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