The Australian zebra finch or chestnut-eared finch (Taeniopygia castanotis) is the most common estrildid finch of Central Australia. It ranges over most of the continent, avoiding only the cool humid south and some areas of the tropical far north. The bird has been introduced to Puerto Rico and Portugal. Due to the ease of keeping and breeding the zebra finch in captivity, it has become Australia’s most widely studied bird; by 2010, it was the most studied captive model passerine species worldwide, by a considerable margin. Australian zebra finches are loud and boisterous singers. Their calls can be a loud beep, meep, oi! or a-ha!. Their song is a few small beeps, leading up to a rhythmic song of varying complexity in males. Each male's song is different, although birds of the same bloodline will exhibit similarities, and all finches will overlay their own uniqueness onto a common rhythmic framework. Due to their extremely fine temporal-auditory discrimination, the Zebra Finch is able to recognise and respond to micro-auditory details nested within their calls which human ears cannot detect.