Despite the images of oil-soaked pelicans flooding the media in recent weeks, wildlife experts say the toll on sea birds from BP's Gulf Coast oil spill is smaller than was anticipated, so far.
That is expected to change drastically for the worse.
Scientists warn that as shifting weather and sea conditions conspire with the dynamics of avian life cycles, a tremendous number of birds will soon be put in jeopardy.
In the coming weeks, millions of waterfowl and other birds that flock to the U.S. Gulf Coast on their annual fall migration will arrive in the region either to roost for the winter or to make brief stopovers en route farther south.
With toxic crude still gushing from the floor of the Gulf of Mexico and streaks of the slick creeping inexorably farther inland, many more birds and other wildlife that nest, feed and find shelter on shore are likely to become casualties.
"To this point, we haven't seen a lot of oiled wildlife based on the size of the spill," U.S. Fish and Wildlife Service biologist Catherine Berg said. "(But) there's still a lot of oil out there. There's still a lot of wildlife in the area."
Birds migrating through the Gulf largely dodged a bullet in the spring when newly escaped oil from the ruptured BP wellhead took longer than expected to wash ashore.
"A lot of those birds were safe on their spring passage, but they won't be safe on their fall passage," said Greg Butcher, bird conservation director for the National Audubon Society.
Wildlife officials are taking various steps to minimize the risks, cordoning off rookeries with containment booms, paying farmers to flood fields that could serve as temporary bird-friendly wetlands, and considering new duck hunting restrictions.
Authorities are even weighing the possibility of capturing baby pelicans to move them out of harm's way, said Jay Holcomb, head of the International Bird Rescue Research Center.
Rehabilitation centers in the Gulf have treated over 800 oil-impaired birds and released at least 250 back to the wild.
The birds are tagged, and some have come through twice, said Holcomb, who oversees rescue operations out of the main treatment facility in Fort Jackson, Louisiana.
"A lot of these birds want to come back to their nest," Holcomb said. "Most spills are over really quick, but this is like a new spill every day. It's really discouraging."
A container labeled "Bird Carcass Collection Drop Box" in a corner of the Fort Jackson center is a grim reminder of the difficulties the rehab teams face. Over 100 oiled birds brought there have died or been euthanized, Holcomb said.
To date, more than 2,000 dead and debilitated birds have been counted along the entire Gulf Coast quadruple the number reported a month ago when the government first began posting its daily tallies.
But Holcomb said partial or skeletal remains with no visible signs of oil exposure account for most of the 1,165 dead specimens found so far and unlikely were spill victims.
The high proportion of older remains from birds that died of natural causes can probably be attributed to the intense efforts to find and catalog every animal that may have been killed or injured in the disaster.
Those counts are more than just academic. They ultimately will help determine how much BP will be expected to pay into a compensation fund for wildlife damages.
Dr. Michael Ziccardi of the Oiled Wildlife Care Network at the University of California at Davis, said dollar figures attached to birds counted as casualties of past spills have ranged from $500 to $20,000 per individual. Factors include whether the bird was an endangered species and whether any economic or commercial value could be ascribed to the animal.
As disturbing as pictures of oiled wildlife have been, the 850 oil-fouled birds found alive to date and hundreds more known to have died pale in comparison to the 250,000 seabirds estimated to have perished from the 1989 Exxon Valdez spill in Alaska's Prince William Sound.
"That may change as time goes on because more and more birds are probably going to be oiled," Holcomb said.
Experts say high winds and seas from any number of storms, including Hurricane Alex, could push more oil into the fragile patchwork of salt marshes, beaches, islands and inlets composing the Gulf's ragged shoreline. The 2010 Atlantic hurricane season that officially began last month is expected to be one of the more active in recent years.
Moreover, the Mississippi River's drainage into the Gulf is starting to dissipate after a robust spring outflow -- fed by heavy rains and Tennessee floodwaters upstream -- that helped keep oil away from shore in the early days of the spill.
As the river levels fall, the Gulf's waters will be drawn back up toward the mouth of the Mississippi and farther into the delta, along with more of the oil on the surface.
Pelicans, gannets and other plunge-diving species were among the hardest-hit at the spill's outset because they feed in open water -- where the oil was then most present.
Shorebirds such as sandpipers, and wading species like egrets and herons, are next in line.
"We have a lot of birds on rookeries. We have a lot of birds in the marshes, just roosting locally. Pretty soon, we're going to get an influx of waterfowl as they come in here to molt post breeding season," Berg said.
After mating and nesting in freshwater inland areas, many ducks and geese venture to the coast to molt, losing their worn summer feathers, then growing winter plumage, before continuing their fall migration. In between, they are flightless.
"Think about it. A whole bunch of ducks that can't fly, on the water," Berg said.
The U.S. Gulf Coast straddles the Mississippi Flyway, one of the world's major bird migration corridors and one that brings about 1 billion birds from more than 300 species through the region each year.
Tens of millions of sandpipers and plovers from Alaska and Canada will be arriving within days on their way to Latin America, Butcher said. Most roost in the uplands away from shore but venture down to the beaches, mudflats and sand bars to feed at low tide.
Herons and egrets that have stayed fairly stationary while nesting are now on the move with their young, potentially becoming more exposed to oil in the marshes, he said.
Hoping to create safe, clean rest stops for migrating birds as alternatives to wetlands fouled by oil, a land conservation agency of the U.S. Agriculture Department announced this week it would pay growers to convert cropland to bird habitat by flooding rice fields.
Gulf authorities have had success here and there in keeping oil out of some prime bird real estate.
Hundreds of pelicans and other birds remain safe for now on Grand Terre Island, a major roosting ground in Louisiana's Barataria Bay that has been encircled with soft and hard boom.
Plaquemines Parish President Billy Nungesser and other local officials made the island's protection a top priority, though they acknowledge that a large storm could tear through the artificial barrier. Some of the surrounding marshes already have been fouled as oil continues to creep farther, especially during morning and evening tides.
"God forbid if we have another Katrina, we'll be picking oil off Bourbon Street," Nungesser said.