The big jump in ruffed grouse drumming counts (nearly 50 percent statewide) announced this week by the Minnesota Department of Natural Resources is reason to cheer. Mysterious as these birds are in their habits and choice of habitats, they are even more so in the cyclical rising and falling of their population.

So, an apparent increase in numbers — whatever the reason — is good news.

Yet until hunters in the field this fall actually see that grouse are more abundant, I wouldn't get too excited. Something seems to have been affecting grouse in recent years, as increases — granted, none has been as significant as the most recent hike announced by the DNR — in drumming counts haven't seemed to materialize in higher bird numbers.

Various explanations are possible.

One is that the rising and falling of the ruffed grouse population is so steeped in mystery that tracking these birds definitively — whether by drumming counts or any other method — essentially is an exercise in guessing.

Obviously, availability of habitat is important over the long term. The late grouse researcher Gordon Gullion stressed the importance of "edge'' cover that exists between and among aspen forests (especially) of different ages.

On that front, changes are difficult to track, even in Minnesota, which arguably (actually, it's beyond dispute) offers the best ruffed grouse hunting in the nation.

(Reasons are twofold: Lots of public land, and generally widespread availability of grouse-friendly forest cover.)

But what's happened to (northern) Minnesota forests in recent years?

Lots, actually, and much of it unnoticed by upland hunters, much less by the general public.

Consider:

• Lack of cutting on national forests, due to lawsuits and threats of lawsuits by "environmental'' groups. The trend here is well-documented, and doubtless has affected various wildlife populations, among them ruffed grouse — which (see Guillion reference above) do best in the mix of forest-age classes that cutting produces.

• The economic downturn and the resulting slowdown in cutting on state and private forests. In the early to mid-1980s, timber cutting (particularly of softwoods) across northern Minnesota was really cooking, as particle-board plants near Cook, Minn., and elsewhere operated at or near capacity to fill orders from the construction and home-building industries. Now some of those plants are shuttered, and cutting has slowed dramatically.

• Timber cuttings are conducted differently now than in the past. Guillion and other grouse advocates traditionally have, as above, advocated clear-cutting to aid wildlife, including grouse. Not hundreds of acres of clear-cutting at once, but in relatively small parcels, say 40 to 80 acres (which affects forests not unlike wild fires did, traditionally). But clearcutting is not looked on as favorably any longer, as advocates for forest diversity have contributed to significant forest-management policy changes. Among these is the leaving now in many instances of hardwood "snags.'' Result: Instead of a northern Minnesota clearcut that would be regenerated virtually entirely by fast-growing aspen, cuttings are occurring on which pines, oaks and maples (among other trees) are allowed to remain standing. Shade provided by these leftovers inhibits aspen re-growth. Yes, this generally is good for a mix of wildlife and forest diversity. But for grouse, clearcutting seems a better way to go.

That said, ruffed grouse remain a mysterious lot.

Why is it that in recent years, for example, as its population should have increased, based on spring drumming counts, haven't hunters found more grouse?

The most likely explanation is that weather-related nesting conditions didn't produce the expected hatch.

But it's possible also that something else is at play — something such as West Nile disease, which some observers theorize could be killing enough grouse each summer to stunt expected population increases.

Time will tell. Or — given the manifold mysteries surrounding ruffed grouse — not.

But if hunters don't find significantly more grouse in the woods this fall, something's significantly amiss.