Although considered a resident bird across Japan, the Oriental Greenfinch is rarely seen in the spring and fall on the Nansei Islands. In the winter, a slightly larger subspecies will come to Japan from the north. With a distinctive call of “kiriri” and a simple song of "been" in the spring, the Oriental Greenfinch has an easily identifiable voice.
Play birds singing
Because the Oriental Greenfinch is similar in size and shape to the Eurasian Tree Sparrow, if you don't pay careful attention, you could easily mistake it for a sparrow.
Unless you're close enough and can view it under directly lit conditions, you won't be able to see the subtly beautiful coloration of the Oriental Greenfinch. And you won't notice the yellow pattern on its wings unless you get the chance to see it in flight. While Japanese Bush Warblers usually go unnoticed during the fall and winter months because they don't sing during these seasons, even when they make an appearance in a garden or park, greenfinches, due to their lack of eye-catching color, often suffer the discourtesy of escaping notice despite their year-round presence.
If you are familiar with the call of a greenfinch, you will notice how it is distinct from that of sparrows. When you see one perched on a power cable, pay attention to its tail feathers. Unlike sparrows, the center of the tail displays a concave shape in the center similar to the tail fin of a saury fish. In the spring, you can observe its courtship behavior, which you won't see with sparrows. This behavior, in which the male bird feeds the female, is called courtship feeding and is common to birds of the Fringllidae, Paridae and Corvidae families.
Insects are a staple in the diet of most small birds. While sparrows and Meadow Buntings, which mainly eat seeds, will feed insects to their chicks, Oriental Greenfinches only feed seeds to their young. Because seeds are difficult to digest, their crop, an expandable pouch used to store food, must be well developed. Anyone who has fed the chicks of such pet birds as canaries, Java sparrows or society finches, knows that a crop is a digestive organ that is part of the esophagus. Its function is to store food and soften it using the bird's saliva.
Typically, thick-billed birds that feed on seeds are more commonly kept as pets as they are easier to feed and care for than insect-eating birds.
A distinctive feather pattern is common to birds that form flocks. Such patterns are believed to function as a danger signal. When greenfinches spread their wings during flight, the yellow pattern on their flight feathers appears as a yellow band.
The Oriental Greenfinch will use its thick beak to eat seeds, and while it can even crack open and eat sunflower seeds, they usually eat the seeds of dandelions found in open fields and along roadsides.