About Kaloula borealis (Barbour, 1908)
The boreal digging frog, scientifically named Kaloula borealis, is a species of microhylid (also called narrow-mouthed) frog that occurs in Northeast Asia. Its distribution spans most of central and northeastern China, the Korean Peninsula, and Jeju Island. Adult boreal digging frogs reach approximately 4.5 cm in body length. They have a round body shape, with speckled skin that resembles that of a toad. Tadpoles of this species grow up to 35 mm (1.4 in) in length. This frog is common across most of its range, but it is classified as an Endangered category II species in South Korea. It lives in cultivated fields, including rice paddies, and is often found living close to human settlements, at altitudes between 10 m and 900 m above sea level. Boreal digging frogs breed during the annual rainy season, which falls around June and July. After the rainy season ends, they dig underground burrows and only emerge at night to forage for food. Females lay eggs in groups of 15 to 20 in temporary pools formed by monsoon rains. The tadpoles mature within 30 days, which is much faster than most other frog species native to this region.
