Zebra finches are tiny songbirds that originated in central Australia and were later introduced in Europe and South America, in areas where trees and bushes lack, as they favour savannah and subtropical heat. Pretty inclined to adaptation and coexistence, they are also likely to be found in human-disturbed localities.
These chubby creatures usually range from 8 to 12 cm in length, and weigh less than 12 g.
Despite their name, they are not striped. In fact, the small strip they have got under their eyes reminds a drop, which is what their scientific name drew inspiration from. Taeniopygia guttata derives from the Latin word gutta, that means tear.
But what makes these birds so unique?
According to research conducted at UCBerkeley, zebra finches have a gift for language mapping, an ability that enables them to recognize singular sounds of their feathered peers and differentiate them so as to spot which vocalizations belong to which bird.
In a two-part experiment, led by Professor Frederic Theunissen, 20 finches were first trained to distinguish sounds through a reward system and then assessed for their performance in choosing the song that would yield birdseed. They did so well that four of them, which were given the task to analyse 56 different peers, recognized an average of 42 birds and their signature sounds.
To demonstrate that parents were preparing off-springs for global warming, Mylene M. Mariette and Katherine L. Buchanan observed that zebra finches call to their eggs only when the external temperature rises above 26°C.
Researchers first recorded incubation calls of 61 female and 61 male birds.
Then they exposed finch eggs to either single or regular recorded parent contact calls. Once eggs hatched, the fledglings subject to the single type of call, which is commonly chosen by this species, were lighter than those which were regularly controlled. Although this might seem unfavourable, a reduced mass would benefit finch health at stressful higher temperatures.
Like many other animals, zebra finches interpret red as a sign of attractiveness. Consequently, biologists at St. Andrews University and James Hutton Institute, conducted a study to test whether finch males' attractiveness influences the number and size of eggs their daughters produce.
After randomly fitting red or green leg rings to 70 male birds, they found that females paired with attractive, red-tagged fathers gave life to larger daughters. Once daughters were sexually mature, they paired with males whose attractiveness had not been manipulated with colours and they still produced more and heavier eggs.
When it comes to high competition, mating preferences drive selection. For instance, female zebra finches would prefer to mate with males with the same song dialect. Namely, a language with similar sound patterns that change depending on the geographic location.
Researchers at the Max Planck Institute for Ornithology studied four captive populations of birds to investigate the effects of their pickiness.
In the experiment, 120 female and 120 male finches were housed in 10 aviaries, according to the degree of competition biologists wanted to recreate. In case of high competition, 8 female finches had to compete over 4 preferred males with the same song dialect. While 25 percent of females however opted to stay single, 31 percent of female birds turned out to be flexible enough to pair with a male with different sound patterns for the sake of reproduction.