The whales will arrive in Baltimore the same way the Colts left: by caravan, under cover of darkness.

The Big Belugas are coming.

If all goes as planned, the National Aquarium's newest prizes -- two young female beluga whales from the Arctic -- will slip into town one night this month.

The silvery 900-pound belugas, which are a protected species in Canada as well as this county, have been at the New York Aquarium since shortly after their capture off Manitoba, Canada, last summer. They were scheduled to be moved to Baltimore early this fall, but aquarium officials have held off, fearing that extremist animal rights activists who object to the keeping of whales in captivity will try to hold up the caravan. A delay of that kind could cause stress to the belugas and endanger their health, officials said.

During their stay in New York, the whales have been getting acclimated to captivity, graduating, for example, from hand feeding to snapping up dead mackerel on their own.

The whales appear to have been making their own study of the solicitous humans who have hovered near their tank around the clock for months. When one approaches, they hurtle up to the surface, loll on their backs and give the person a seemingly bemused once-over.

Their handlers have given them Eskimo names -- Illamar, which means "friendly," and for the more independent of the two, Anore, or "the wind."

Belugas turn snowy white by the time they reach adulthood. They are also known as "sea canaries" because of their frequent squeals, clicks and trilling sounds.

Anore and Illamar may be big and noisy, but they are sensitive, hence the secrecy surrounding their travel plans. The belugas are among the smallest of whales, and are much like dolphins in intelligence, appearance and behavior. Adult belugas are two to three times the size of dolphins, but they have the same gregarious nature and a similar fixed smile that endears them to humans.

Officials expect the whales to be instant favorites at the aquarium, perhaps even eclipsing the sharks in popularity.

Animal rights groups in Baltimore have protested the removal of the belugas from their ocean environment and plans for their placement in an aquarium tank.

In recent months there have been occasional picketers and a letter-writing campaign, and at least a few aquarium patrons have canceled their memberships.

Protesters have argued that marine mammals in the past have not fared well at the aquarium.

Last year, one dolphin died of an illness it contracted prior to its arrival, and in 1982 three dolphins doing poorly had to be moved.

Aquarium officials said they have tried to ensure that the beluga's specially designed holding pool will be a comfortable environment.

Associate aquarium director William Flynn, who led the expedition to capture the whales and has been shuttling back and forth to New York overseeing their progress, said the belugas will be "ambassadors" of their species who will educate thousands of schoolchildren about whales and the need to protect them from slaughter.

"These two animals as individuals will probably do more for their species than all the 'Flipper' shows combined did for dolphins," said Flynn.

Flynn and other aquarium officials expected some groups to oppose the whale exhibit, but what they are worried about is what Flynn termed "the radical fringe."

One night in September two protesters broke into the New York Aquarium and posted a "Don't Jail the Whales" banner. One of the men chained and padlocked himself to a filtration grate in the whales' pool. The other tied himself to the top of a 50-foot pole. A special police team had to be called in to remove them.

"What if the guy in the pool had drowned or the other guy had fallen off the pole -- or a cop had fallen off trying to get him down?" said Flynn.

Partly as a result of that incident, the expected early fall arrival of the whales was delayed.

Flynn decided to make some minor changes in the special outdoor holding tank being readied for them on an upper level of the aquarium in Baltimore.

Flynn said he plans to bring the belugas to Baltimore by caravan at night, when temperatures are cool and there is little traffic.

The whales will be loaded into a truck on foam-supported stretchers. They will be sprayed with water, and their fins and tails will be packed in ice to regulate their body temperature.

The belugas have already missed last week's "members only" party to officially welcome them to the aquarium, but Flynn said he plans to get them to Baltimore before the month is out.