All a squirrel hunter needs is a tall stand of oak trees, a smooth spot to sit on and permission to hunt.

There are oak trees galore in our part of the world, and, if it comes to it, a serious hunter can do without the smooth place. But what about permission?

Not many landowners close in to Washington care to have shotgunners cluttering up woods for which they paid a fortune. Anyway, hunting is against the law in heavily populated areas.

What urban squirrel hunters need is a good close-in spot with deep woods accessible to all. They have it in McKee-Beshers Wildlife Management Arc off River Road just outside elegant Potomac.

McKee-Beshers is 1,500 acres of intensively managed woods, swamps and farm fields. Next door to it is Seneca Creek State Park, also about 1,500 acres and also a carefully managed wildlife habitat.

Both are public hunting areas and, while neither can match virgin, rural woods for success rates, both offer respectable, scenic and reasonably productive hunting at no cost.

Best of all, they're a half-hour drive from Washington. Seneca Creek opened to full-time hunting yesterday. As a state park it falls under Maryland directives keeping hunters out until the season is well under way.

McKee-Beshers has been open since the seasons started. We stopped there last week for a quick scouting expedition, and we liked what we saw.

The area is in the buffer zone between the Potomac River and River Road. Half is forested in tall hardwoods and the outer half is swamp or fertile fields planted in active farm crops, mostly corn and soy beans.

Bob Beyer, district wildlife manager,said he leases the fields to local farmers, with the proviso that he establishes what is to be planted and where. The result is a mix designed to enhance the habitat for three "featured species" of game - squirrels, quail and ducks.

By far the most popular of those is squirrels. According to reports filed by hunters, they spent almost 2,500 hours in the McKee-Beshers woods in 1976 and harvested 274 bushytails. Last year the hunt dropped off to only 784 hours, but hunters still reported 200 squirrels.

Bever works at keeping squirrel numbers up by managing the woods specifically for them. "We're on a 200-year cutting cycle," he said. That means tall hardwoods stay tall for the squirrels, at the expense of other forest wildlife like deer, which favor lowcut, brushy cover.

Beyer manages his farm fields for quail, which comes into season in Maryland Nov. 7, by favoring corn digenous species," he said, "where pheasant isn't. Because we've got bottomland, where nests flood easily, we can't count on good rabbit production. So we manage the farmland principally for quail."

Last year hunters spent 263 hours in the fields pursuing quail. They bagged only 15, though the year before they had taken out 48 bobwhites.

The third factor in Beyer's equation, ducks, don't need much managing. McKee-Beshers is natural duck habitat. Swamps and loughs predominate in the acreage farthest from the river, and with the tall hardwoods nearby it makes for ideal wood duck habitat. "The last time I was down there for a wood duck count we counted 637 coming in in one evening," Beyer said.

How did they count them? "Fast, very fast."

Last year hunters spent 281 hours in the McKee backwaters and harvested 43 ducks, mostly by jumpshooting, Beyer said.

None of these figures is likely to send a wizened hunter springing for his shotgun. It's a far cry from bang-bang hunting.

But McKee and neighboring Seneca Creek have other charms. For this urbanite, they offered a pleasant chance to go exploring in a wilderness that was big enough to get lost in and small enough to find his way out. They offered insight into the ways of farming and a midday rest along the Potomac banks where smallmouth bass splashed and jumped on the still water.

In four hours in the hunting grounds we saw no other hunters, though we did hear a few shots.

McKee Beshers and Seneca are open to hunters six days a week. McKee requires a check-in at the Seneca Creek park headquarters on River Road, where you pick up your daily permit and parking stamp. Only 25 hunters and permitted there at a time.

On most weekdays there's no crowd, but on weekends and first-days of seasons it is best to get a pass in advance. They are issued up to a week ahead of time.

Seneca Creek requires no checkin. Hunting pressure there is regulated by the number of parking spaces.

Neither area manages for doves, which are popular small game hereabouts. But there is a tie-in with the Izaak Walton League's 40-acre dove field a mile away, that is open to the public Wednesdays and Saturdays. It also require check-in at the Seneca Creek headquarters.

All three hunting areas require state license, public lands stamps any waterfowl stamps for duck hunters.

The park headquarters is just off River Road about a half-mile west of the Seneca Creek crossing near the town of Seneca. Phone 428-0138 for details.