Development has halved Alberta's grizzly bear population, a wildlife conservation group says.

The Alberta Wilderness Association looked at the most recent provincial counts of grizzly bears and concluded there are only 500 bears left across the province.

Alberta officials had previously estimated that the province had 1,000 grizzlies, association spokesman Nigel Douglas said on Monday.

Development is the main reason for the decline, he said. "Access roads and trails lead to dead grizzly bears. It's as simple as that."

Darcy Whiteside, a spokesperson from the province, said it's too soon to say the population is on the decline because there wasn't an accurate picture of the grizzly bear population before the five-year count began.

"We made a commitment to do a study to accurately assess as best as possible the grizzly bear population and we're standing by that commitment to ensure that that process is completed before we start to look at some of the aspects that those organizations are asking us to look at."

A final report and estimate of the grizzly bear population will be released after the study concludes in 2008.

Last year's ban on hunting grizzly bears in Alberta was a good first step, Douglas said.

"One of the best lessons we can learn is from Yellowstone [National Park in the United States] where they actually had a successful grizzly recovery program. … By reducing that road network they managed to recover grizzly bears," he said.

His organization wants Alberta to classify grizzlies as endangered, rather than threatened, under the province's Wildlife Act.