Yellowstone NP bison population estimated at 3,900, up almost a third
Whether it was an easy spring, fewer wolves preying on them, or simply a good year, the bison herds in Yellowstone National Park have grown by about one-third since winter, according to park officials.
Latest estimates from park biologists put the herds' population at 3,900, up from the 3,000 estimate from the winter survey. The summer survey was conducted from the air in June and July.
According to the park, "this year’s calf production represents 15 percent of the population. Fifty-six percent of the bison are distributed across the Northern Range this summer, while the remainder are found in the Central Interior herd."