Yellowstone National Park's bison herds have grown by nearly 14 percent over 2011 numbers, with most of the animals found across the park's northern range.
The park's summer bison surveys, conducted during three aerial counts, turned up a population of 4,230 bison, park officials announced Wednesday in a release. Of those, about 2,600 bison are in the northern herd, with another 1,600 in the central herd, the park said.
Yellowstone's peak population estimate of 5,000 bison was recorded during the summer 2005. The current 14 percent growth rate is within the natural range of expectation for wild bison, according to park officials.