Japanese quail
The Japanese quail is considered to be a closely related allopatric species to the common quail, though both are still recognized as distinct species. Due to their close relationship and phenotypic similarities, as well as the recent decline in wild common quail populations throughout Europe, the Japanese quail is often crossed with the common quail in order to create hybrids that are used to restock the declining wild quail populations. Countries such as Greece, France, Spain, Portugal, England, Scotland, Canada, China, Australia, and Italy all release thousands of such hybrids each year in order to supplement their dwindling wild quail populations, often releasing these birds right before the start of the hunting season. These hybrids are practically indistinguishable from the native common quail in these areas, though there are worries that such hybridizations could be detrimental to the native quail populations.