The giants soon will arrive offshore. The rare right whales have begun to head south to calve.

An airplane survey crew already is in place in the Lowcountry, waiting on the weather to lift before beginning a winter of flights looking for the mammoths and alerting nearby ships to their presence. For the next five months of calving season, that lone propeller plane and its cramped spotters are on the lookout for some of the most endangered animals in the world and the busy commercial ports of three states.

Ship strikes are considered a leading threat to the whales.

Starting next year, the crossing guard might not be out there so often. The five-year State Ports Authority grant that has been paying half the $440,000-a-year cost of the Sea to Shore Alliance flights will run out next year. For that money, the group will turn to uncertain National Oceanic and Atmospheric Administration grants that now pay the other half.

Dianna Schulte, the survey crew leader, frankly concedes the job can't be done effectively for $200,000. Cynthia Taylor, the research scientist in charge of the effort, said the alliance is hoping NOAA makes up the difference. But more NOAA funds aren't certain, and there might be fewer flights, she said. There's no telling what will happen down the road with budget-crunched public money.

"We might not always fly," she said.

The right whale is the nearly extinct 40-ton, 50-foot-long mammal that whalers all but wiped out in the 19th century. Only about 400 are known to exist today, so few that researchers consider every whale vital to the survival of the species. The whales travel back and forth from their summer feeding grounds off New England to calve in the warmer winter waters off the Southeast coast.

Those waters are heavily trafficked. The presence of the whales and rules to protect them are disrupting everything from commercial shipping to naval warfare training.

Partly because of the aerial survey work, NOAA in 2008 mandated that large ships within 23 miles of the coast must slow to half-speed when the whales are around. Shipping and ports interests fought the rule. Observers say it is sometimes violated by both military and commercial vessels.

The Ports Authority offered the grant in 2007 as part of its proposal for a new shipping terminal at the former Navy base in North Charleston, because of environmentalists' concerns about increased shipping traffic's impact on the whales. That terminal is now in development.

SPA spokesman Byron Miller said there are no plans to renew the grant. "We had an agreement. This is the final year of the agreement," he said.

Taylor said the best protection for the whales is for ships to slow down.

"I know my colleagues, including the State Ports Authority, aren't happy about that," she said. But "we can't change the whale's behavior. We can only change human behavior."

Reach Bo Petersen at 937-5744