This time of year, brewers are brewing special holiday ales, a comforting counterpoint to winter's cold days and long nights. But those big, rich beers require lots of hops, and, as Guy Hand reports, that agricultural ingredient is getting more expensive and harder to find.

Around this time, especially when the weather starts getting cold, people look for a bit more warmth in their beverages, something with a little more body, a little more flavor. And that's what Kevin Bolen's Lost Reindeer Winter Ale provides. "It's a really nice, big, warm beer, real dark amber color, lots of alcohol, lots of hops. It's very, very rich, but it's a very flavorful beer.

Bolen, head brewer at the Ram Pub in Boise, Idaho, explains that hops ? the bitter, green flowers of the hop vine ? are essential to making beer. They add complexity, and counter the sweetness of barley malt, another essential ingredient. "We use this variety a lot in our beers," he says, as he pours some hops into a scale. "The amber and the blond are our two biggest sellers."

Over at Highlands Hollow, another Boise pub, Chris Compton is getting ready to brew his holiday beer. He's been brewing ales since 1992. "I do a strong bitter," he explains. "It's called Thunder Monkey. It's got a ton of hops in it and a big alcohol kick. It's a big beer." Compton says "big" beers are becoming more popular.

"Ten or fifteen years ago, most microbreweries were making some pretty good beer but they were fairly tame as far as flavor went," Compton observes. "Over time, I think sophistication in beer flavors has increased. They've been willing to step over the line a little bit more and finding out that ? you get used to that initial [hops] bitterness a little bit and then you start getting the aroma, you get two inches from your mouth and you could smell that wonderful hops aroma that comes in a good IPA [Indian Pale Ale], or you get that wonderful roast flavor and the mouth feel from a good stout or porter. And all of a sudden you find out, ''Wow! These just have really great flavors.'"

But those flavors and those big hoppy beers may soon get harder to brew. Hops are in short supply. The northwestern states of Idaho, Oregon, and Washington grow all the commercial hops in America. And farmers have gradually cut back on acreage after a decade of overproduction. Bad weather, fires, and growing worldwide demand have also taken a toll on supply.

K.C. Jones runs Brew Connoisseurs, which supplies beer-making ingredients for people who like to brew their own beers at home. "Hops for me are going to be [a challenge] this year just for the simple fact they're getting real hard to get at the home-brew level," he admits. "Some of my suppliers have said I need to find other sources." He says he used to buy hops in bulk, but now he can only get it in smaller quantities.

Even bigger microbrewers ? like Kevin Bolen at the Ram Pub ? are concerned. "There are people all over the country that are looking for hops right now," he says. "I mean, I called up to try to get something a couple months ago, and they [said] flat out, 'We don't have 'em.'" And that means changing the way he makes some of his beers.

Bolen had to alter the recipe for this season's Lost Reindeer Winter Ale, "because," he explains, "instead of trying to go out and look for another type of hop, I used what I had on hand."

Brewers, nationally, are dropping certain beers, altering others, and raising prices. Some beer-makers may even go out of business. The shortages and price hikes could last for years. And that means next season's winter ale may not be the beer of Christmases past.