In Maine, ruffed grouse prefer aspen as a primary food source, and that’s where hunters will find them most often, especially early and late in the day. Bill Marchel/Star Tribune/TNS

Humans in general and hunters in particular are naturally resistant to change. However, every once in a while a change is made that most agree is for the better. Such was the case when Maine moved the start of its upland bird season from the traditional Oct. 1 date to the last week in September. Who could argue about an additional week of hunting opportunity?

There were several reasons for this adjustment, the biggest probably that it allows those participating in the first moose season an additional opportunity while traveling the remote roads of northern Maine in search of bigger game. It also offers sporting camps, lodges and guides an additional week to host hunters, and for hunters in general to get an earlier start on hunting season.

Biologists have determined the additional week won’t be detrimental to grouse populations, which fluctuate annually based largely on weather conditions during the spring brooding season. Cold, wet springs mean poorer recruitment while warm dry ones can bring a bounty of birds come fall.

Historical research shows ruffed grouse populations tend to follow 9-11-year cycles, with peak populations occurring in years ending in 9, 0 or 1. They also show “super peaks” every 20 years, but those only last a year while lower peaks may persist for two or three years. Despite their best efforts, biologists still can’t quite explain the reasons. Predation may play a part. Studies of several species show cycles where as prey numbers rise, predator numbers follow until they catch up, then numbers of both drop.

While these cycles still occur to some degree on a continent-wide basis, populations vary considerably more on a local basis. One reason is the aforementioned weather. Another is food. Grouse feed on a variety of plants and insects but particularly prefer aspen.

“It is not an adaptable bird,” said Gordon Gullion, who conducted some of the classic grouse research over a 20-year span – two full cycles. “When aspen is missing from the range, a bird must spend two or three hours to fill up on these other items, rather than a quarter of an hour on aspen. That’s much more time out in the open, where predators are hunting. And much more time in the cold. Each time it lifts that wing, it’s losing heat. Where aspen is present and snow is an important part of the winter ecology, the ruffed grouse is an aspen-dependent bird.”

That’s a good thing for grouse, and those who pursue them. Aspen is a pioneering species, quickly exploiting disturbed areas like cutovers, which exist wherever timber harvesting occurs. Smaller patch and strip cuts are especially beneficial as they provide an abundance of food while also maintaining a diversity of shelter, nesting and brooding cover.

Rotational cutting is also good practice as the grouse are dependent on different growth stages of aspen. Young stands provide thick cover and protection from predators. Middle-aged stands offer a protective canopy and an open understory where males can more safely attract females. Mature stands produce an abundant crop of catkins (dormant male flowers) that represent an important food source in winter and early spring. While grouse are not tied exclusively to aspen stands, that’s where you’ll find them most often, and so should look, at least early and late in the day.

Another positive side effect from timber harvesting is the miles of dirt logging roads. Grouse are gallinaceous birds. They feed feverishly in the early morning, then sometimes pick gravel, which they ingest to help digest coarse food in their crop. Riding the logging roads for gravel-picking grouse in late morning is a classic and more leisurely style of hunting in Maine, and can be quite productive when the birds are abundant.

Bob Humphrey is a freelance writer and Registered Maine Guide who lives in Pownal. He can be reached at: bhunt@maine.rr.com