The crows take over Aden in the early evening. Squawking, raucous, restless, they flap in clumsy circles and roost in rows on the low ledges of the buildings. The topmost branches of Aden's trees heave under their weight, and the heavy, heated air is full of their noise. The English called them jackjaws. The English brought them, really, inasmuch as the English brought the Hindus and the Hindus carried the birds here from India because they helped to deal with the dead if the funeral pyres did not do their work. Firewood has always been scarce here.

The Yemenis hate the crows and have mounted various campaigns to get rid of them. But the filthy birds endure. They are given to spitting, and the acid from their bellies will eat the paint off a car. The Arabic word for the crow is ghurab -- which Aden has taken on the added metaphorical meaning of "black death."

And that is about all that remains of Britian's influence in Aden.

Today Aden is the capital of the People's Democratic Republic of Yemen, known as South Yemen. Unofficially, however, it falls under the influence of another country altogether.

The port and town of Aden constitute little more than a city-state, naval base and fueling station of the Soviet Union, whose freighters and tankers crowd the harbor (guarded by ships of the Soviet Navy), and whose local guardians of socialism bargain ruthlessly at the few remaining craft shops before heading home, laden with Japanese tape players from the duty-free shop at the airport, on the Aeroflot shuttle to Moscow.

The Moscow shuttle is always running. Four Aeroflot Ilyushin jetliners stand by on an apron at the Aden airport. Down from the main hangars and off to the side is a rank of rednosed mig21s.

"The Mig23s are another place," said a Pakistani pilot for Air Djibouti, a young man who often flies to Aden. "I have seen them with these eyes."

In the port, 12 of the 14 harbor pilots are Soviets.

"I have put into this port many times in seven years," a ship's master from the Seychelles said, "and I have never had any but Russian harbor pilots."

Those who are in a position to know -- none of them will speak unless a promise is given to withhold their names -- say that the Soviets control, with varying degrees of subtlety, every significant ministry of the government, including defense, planning and foreign affairs.

"They let the Cubans run the Health Ministry," one man said. "What do they care? The Russians have their own doctors."

"You can count on this," a European ambassador said, "the Russians will never -- I mean never -- leave Aden unless under force of arms. Which of course no one wants to see happen. Not after the American agreement [to use military facilities]at Berbera [Somalia], with Oman, and Kenyha . . . No, the Russians will never leave, and never, certainly because they failed to manipulate the politics of the country to their advantage."

The barren rock of Aden has a history that is more or less traceable for 3,000 years, and there is fairly clear evidence that people settled here even earlier. From the 10th to the 2nd centuries B.C., it was the seat of the kingdom of Sheba. The Romans came in the 5th century B.C. They referred to Yemen as "Arabia Felix," or Happy Arabia, presumable to distinguish it from the harsh country beyond its borders.

Now, Aden's waterfront shops that once offered goods from every nation in the world are boarded and locked, and the dust of months coats their worn rock steps.

The current head of state is Ali Nasser Mohammed, who in March replaced Abdul Fattah Ismail, who had been secretary general of the Socialist Party Central Committee.

Although no one outside the government knows exactly what happened, it is thought that Ismail, who had been close to the development of the National Security Police [with close Soviet or East German advice] tried to bring the army under his wind. Somehow, this move was countered and it was announced that Ismail had stepped down to an honorary post as president of the Central Committee.

"No one really knows what is going on," a diplomat who has followed the situation said. "It isn't certain whether he has fallen out of favor with the Russians or whether, indeed, he is their man for the future, since there are indications that they have protected him, taken him under their wing. I don't know, but I can tell you one thing -- the Russians, every step of the way, are in back of what goes on here. It is too important for them to leave things to chance."