The early settlers called the ruffed grouse "fool hen." The name fit well for the tasty, white-fleshed birds that sat still while pioneers walked up and clubbed them with a sick.

The hen is foolish no more. The ruffed grouse (please, not ruffled) has evolved into the williest of upland game birds - sly in habit, dextrous on the wing and exasperating to hunt even with modern shotguns and plastic - sleeved shells.

Normally thought of as a Northern bird, the grouse thrives in the footgills and ridgetops of the Appalachians as far south as Georgia. In Virginia alone ruffed grouse enticed 40,000 hunters into the woods last year.

This season hunters have faced major changes in bag limits and cutbacks in hunting time in the Old Dominion. The grouse is in trouble.

In Southern states grouse populations do not follow the general 10-year cycle many Northern birds are believed to hold to.Instead, says Joe Coggin, who handles ruffed grouse research for the Virginia Game Commission, "They fluctuate in an erratic manner."

A downward trend showed up in the 1974-75 season, when hunters flushed only 0.9 birds per hour, compared to 1.3 birds the year before. The 1975-76 season saw 1.0 bird per hour moved by hunters who joined in a state survey, but last year rates plunged to a low of 0.72 birds flushed per hour of hunting effort.

More alarming than the decline in flush rates is the decline in juvenile birds bagged by hunters. For a thriving grouse population, the number of young birds should be between 65 and 70 per cent; three young birds should fall to the hunter's gun f or every adult hen. But for three years Virginia's ratio has been below that. Last year less than one young bird was taken for every adult hen.

With those figures in mind, the game commission shortened the season this year by two weeks, moving the closing date up to Jan. 31. The bag limit was lowered to from three to two birds per day and the season limit was cut from 15 to 10 grouse per hunter.

There was opposition to the changes, but the need for increased protection won out. As Coggin said, birds that survive until February are birds that will be around to mate in the spring. They do not represent surplus grouse that might perish over the winter anyway.

One of the periods in the life of grouse that game managers have always lacked information on is the stretch from spring through fall. Even after large broods of young birds have been sighted in spring, flush rates are sometimes low when hunting season rolls around.

What happens to the young grouse? Predation from owls, hawks, foxes and other beasts takes its toll. Disease is a factor. But the reason for much of the loss still is left to educated guessing.

Coggin hopes to break some ground with a new study concentrating on the spring-fall period. Transmitters are to be placed on hens and some of the young chicks as they mature so that researchers can track their whereabouts and see what caused the heavy loss of birds.

At the same time the wing and tail feather survey continues. Cooperators are needed to aid in this monitoring effort, and hunters are invited to write to Coggin, Rt. 1, Box 239, Fagle Rock, Va. 24085, for a grouse survey package. A central tail rectrice and portion of the wing of birds bagged are required of participants, and brief records must be kept for each hunt.

All the news on the grouse front is not bad. The same dry, warm spring of 1977 that allowed a bumper crop of turkeys to hatch has also nurtured an upswing in numbers of young grouse. Good nesting success was reported in the spring, and word from the brush-choked mountain hollows is encouraging.

Our friends may have turned the corner.