JACKSON, Wyo. (AP) -- The large population of bison in Yellowstone National Park could lead to an increase in hazing operations outside the park this winter, officials said.

Wildlife managers counted 4,700 bison in the park in August 2007, up from 3,900 for the same month in 2006. The bison population peaked at 4,900 animals in 2005. The large bison population could force more of the animals to seek food at lower elevations in West Yellowstone and near Gardiner, Mont., officials said.

Yellowstone spokesman Al Nash said bison movement depends on the weather.

''With the numbers that we have, we're going to see some animals leave the park,'' Nash said. ''It's a question of what weather conditions we may have and whether that will affect bison movements.''

Heavy snowfall won't necessarily prompt bison to move to lower elevations, Nash said.

''They are built to deal with a lot of snow,'' Nash said. ''It's very impressive to watch them use that big shoulder muscle and that big head like a plow to clear away deep snow to get at the food underneath.''

However, Nash said freezing rain or a thaw followed by a freeze would make it more difficult for bison to reach forage. ''That would be one type of weather incident that certainly could prompt bison to seek forage elsewhere,'' he said.

Bison sometimes move as early as December, Nash said, but usually move from February to April.

Yellowstone wildlife managers and officials with the Montana Department of Livestock are preparing for a busy winter, Nash said.

''All the agencies realize that the potential exists this year for bison movement in some significant numbers and severe weather,'' Nash said. ''If it were to occur, that certainly has the potential to increase the animals that may leave the boundaries.''

The Montana Department of Livestock is the lead agency for hazing operations, and typically handles bison that have left the west entrance of the park into West Yellowstone. Yellowstone wildlife managers often haze bison that leave the north entrance into Gardiner.

If hazing doesn't work, agencies have authority to capture bison and ship them to slaughter. The State of Montana also started a bison hunt in 2005 and hunters have killed 44 bison in the hunt so far this winter.

During the 2005-06 winter, hunters and wildlife managers killed 1,016 bison combined.

Stephany Seay, media coordinator for the Buffalo Field Campaign, called the hunt and the slaughter a ''sorry approach to wildlife management.''

''They are already telling us explicitly that they're going to be really aggressive on the buffalo once the hunt is over,'' Seay said. ''It sounds like they're intending to slaughter quite a large number (of bison). We're certainly not pleased.''

Seay said that conservation efforts that set aside land outside the park for bison are a better option. She said some landowners already have agreed to allow bison to roam unmolested on property in West Yellowstone.

Tim Stevens, Yellowstone program manager for the National Parks Conservation Association, said he agreed with Seay that management of the Yellowstone bison herd is ''heavy-handed.''

Steven said wildlife managers should make sure the bison have access the habitat that they need.