That Bird Blog – Bird Care and History for Pet Birds

Traditional wisdom holds that birds rely chiefly upon eyesight and hearing in getting about.  This month (July, 2008), however, biologists at Germany’s Max Planck Institute of Ornithology established that a number of species use olfaction (sense of smell) in navigation, foraging and, perhaps, recognition of other individuals.

Those who study and observe birds have long suspected this, at least as concerns a few species.  While in Costa Rica on field research, I got into the habit of setting out baits in order to see what animals might show up to feed (in contrast to popular belief, rainforests are not teeming with readily visible animals.  The animals are there in droves, but most go about their business undetected).  After placing a road-killed giant anteater in a heavily-forested area, I was quite surprised to find that turkey vultures (Catharses aura) appeared at the carcass in short order.  I had always assumed that these birds detected food by using their sharp eyes while soaring high above ground.  Yet they found the anteater very quickly, despite being unable to see it due to the dense tree cover.  Could they have detected its scent?

The nostrils of New Zealand’s brown kiwi, which forages for earthworms at night, are placed at the tip of its bill.  This odd arrangement has long caused ornithologists to speculate that the flightless bird locates its prey by scent.  Another oddball from that island, the kakapo, searches for fruit at night.  The world’s only nocturnal, flightless parrot, the kakapo is one of the birds now known to have a powerful sense of smell.

The biologists at Max Planck studied the olfactory receptor genes, which form the molecular basis of the sense of smell, of various species (including those mentioned above) in coming to their conclusions.  Their results were confirmed by examinations of the olfactory lobes of the brain, which were larger in those species thought to have a well-developed sense of smell.

It is amazing and inspiring that there is so much of importance still to be discovered about very basic areas of bird biology.  Pay close attention to what pet and wild birds do – great opportunities await careful observers.  

You can learn more about the work of the Max Planck Institute of Ornithology at:

http://www.mpg.de/english/institutesProjectsFacilities/instituteChoice/ornithologie/index.html

Brown Kiwi image courtesy of Malene Thyssen, http://commons.wikimedia.org/wiki/User:Malene

The work showed that pigeons have a well developed sense of “self”, and can distinguish their own images from those of another pigeon after a delay of up to 7 seconds. This places them ahead of most human 3 year olds, who fail at self-recognition tests after a 2 second delay. Amazingly, the pigeons were also taught to distinguish the paintings of Van Gogh from those of Chagall – a task at which, I am embarrassed to say, I would likely fail!

Prior to these findings, only mammals with highly-developed brains, such as chimpanzees, elephants, dolphins and (possibly) dogs, were known to be capable of recognizing their own images.

In another interesting project, Rohr University Bochum (Germany) biologists were able to determine that pigeons moderated their choice of a large versus a small reward based upon how long it took for each reward to be delivered. The research revealed that pigeon impulse-control is regulated by a single forebrain neuron, and could have important implications for the treatment of addictive and attention-deficit related disorders in humans.

Parrots seem, at least on the surface, to exceed pigeons in their learning abilities – I imagine that we will eventually learn that they have other very advanced capabilities as well.

An interesting article concerning the similarities between how birds and people perceive the world around them is posted at:
http://www.sciencedaily.com/releases/2007/02/070220131646.htm

Zebra Finches in the Wild
We are so accustomed to seeing zebra finches in cages that it is easy to overlook their existence as vital members of a natural environment. However, free-living zebra finches are perhaps the most abundant birds in the interior of their native Australia. With the exception of coastal Victoria and New South Wales, they inhabit the entire continent. In fact, their range is expanding due to the provision of water (they must drink daily) on livestock farms. A subspecies of the zebra finch (which was actually the first member of the species to be brought into captivity), the Lesser Sunda zebra finch, occupies nearby Timor and the Lesser Sunda Islands.

Classification
Despite their common name, zebra finches are not true finches but rather are classified as waxbills, in the family Estrildidae. Nearly 150 species of waxbills range throughout Africa, Asia and Australia. A number of the zebra finch’s relatives, including the gouldian finch, the cordon blue and the white-backed munia, are also popular in the pet trade. The nearly 200 species of true finches (family Fringillidae) are absent from Australia.

Habitat and Adaptations
Zebra finches favor open woodlands, grasslands and farms, but can also be found in Australia’s harsh, arid interior scrublands. They feed mainly upon seeds, especially those of various grasses, and take insects as well. Populations living in salt marshes have evolved the ability to drink salt water – excreting excess sodium via the kidneys. They are fairly sensitive to temperature and cannot generate enough heat for egg incubation if temperatures fall below 53 F.

Breeding
Like many of its relatives, the zebra finch forages in large flocks. Within the flock, however, monogamous pairs form. The pair bond appears, in most cases, to be life-long. Breeding is sporadic throughout the year and may not occur at all during droughts. As an adaptation to the harsh environment, this species has evolved the ability to breed quickly at the onset of rains during nearly any time of the year.

Zebra finches nest as discrete pairs, but communally – that is, with many pairs occupying the same tree. The female chooses the nest site and constructs the nest with dried grasses and other materials brought by the male. The 4-5 eggs are incubated by both parents and hatch in 13-16 days. The young, fed by the male and female, fledge in 20-21 days. In years with favorable rainfall and food supplies, 3 or more broods may be raised. The zebra finch’s ability to take advantage of good conditions can be a handicap in captivity – in response to the abundance of food and water, females may lay so often that their health suffers (this problem can be ameliorated somewhat by removing all nesting material).

A View from Taiwan
As mentioned earlier, zebra finches are popular pets, both here and abroad. A Taiwanese friend has informed me that they are much more “house pet” than “cage bird” in her country, and are commonly allowed to roam about. Her pet zebra finch would perch on a chair while the family ate dinner – begging for food but not actually approaching the table, and would sleep in her shirt pocket in the evening.

Further information on the parallels between zebra finch song the acquisition of speech in people is available at:
http://www.zebrafinch.org/

The Role of the Brain
Although birds are linked in our minds, to song, only a very small percentage of the world’s 10,000+ species – those classified within the suborder Oscines – actually sing (and the voices of some of these, such as the crow, stretch the definition of “song”!). Baby zebra finches, much like human babies, babble on with an infinite variety of noises – practicing until they eventually learn the adult song. Once learned, the song is never varied.

Research completed last month (May, 2008) at MIT has revealed that two distinct brain pathways are involved – one for learning the song, the other for producing (singing) what has been learned. Damage to the learning pathway of a young finch prevents it from ever producing the adult song, but the same damage during adulthood has no effect on the bird’s singing abilities.

Bird Song and Human Speech
The MIT researchers have drawn some parallels to human learning abilities that bear further investigation. In zebra finches, the youngster’s vocal explorations cease once the adult song has been acquired, as the song never changes. However, the learning pathway is retained, possibly as a back-up system – damage to the song-producing pathway of an adult causes the bird to revert to sounds produced during the learning phase. We humans rely greatly on learning abilities, or pathways, throughout our lives, yet certain aspects of speaking, such as our ability to learn a language without an accent, must occur during childhood. So perhaps we also utilize, at least to some extent, two separate brain pathways when learning and producing sound.

Instinct and Mimicry
In all birds there seems to be an instinctive “song framework” that is filled in by learning and mimicry – male birds raised in isolation develop only incomplete songs that are not recognized by others of their species. The specifics of how the various popular pet birds learn their songs vary from species to species. Baby zebra finches pay attention only to the song of the male that actually feeds them. For example, zebra finches incubated (in captivity) by Bengalese finches grow up to sing the song of their foster parents – this despite the fact that the nestlings could hear other zebra finches singing nearby! How they know which song to choose among the many they hear is not yet understood.

The pet birds most valued for their singing abilities, such as canaries and shama thrushes, copy a wide variety of songs, not only those typical of their species. Indeed, owners of these birds can improve their pets’ vocal repertoires by exposing them to “tutor birds” of the same or different species. A favorite story among canary fanciers is that of a canary which learned to whistle the melody to “God Save the King” by listening to a trained bullfinch do the same in an adjoining room……if the bullfinch hesitated too long while singing, the canary would jump in and finish the melody at exactly the right point!

Over 80% of the world’s parrot species have some degree of red coloration, the intensity of which is only rarely found among other bird families. While most birds acquire their red coloration through carotenoids (naturally occurring compounds) ingested along with food, researchers at Arizona State University have shown that parrots utilize a previously unknown system.

Parrots manufacture red pigment internally. This pigment, a suite of 5 molecules, is found in all red-colored parrots, but, as far as we know, nowhere else on earth. Also unusual is the fact that the pigment seems to be synthesized at the site of each growing feather, and that it has anti-oxidant properties as well. This finding has very important implications for ornithologists, as it points to a very unique evolutionary history among parrots and their relatives (of course, parrot owners have long known how different parrots are from other birds!).

Once again, studies of a species’ natural history have given pet owners important insights as well. Pigment production is a drain on the parrot’s metabolism, and a vitally important process given its anti-oxidant properties. It is, therefore, vital that pet owners provide their parrots with a nutritious diet and proper care.