Part of an ongoing series on the environmental impacts of the Gulf oil spill.
Some experts—citing traditionally low survival rates for rescued birds—are controversially arguing it would be better to immediately and humanely kill the suffering birds.
In a Spiegel Online article last month, German biologist Silvia Gaus argued that workers helping birds caught in the Deepwater Horizon oil spill, should "kill, not clean." Gaus said studies show that more than 99 percent of rehabilitated birds will die anyway as a result of oil exposure, mainly due to kidney and liver damage caused by oil ingestion.
Each oil spill is different, however, and survival rates often depend on factors such as climate and species, according to Nils Warnock, a wildlife specialist with the Oiled Wildlife Care Network at the University of California, Davis.
No one knows what the survival rate will be for the Gulf species affected by the oil spill. But, Warnock said, "I don't believe that all these birds that are being rehabilitated for the Deepwater Horizon spill will end up dying."
He added that Gaus's statistics are related to past North Sea oil spills, where birds are more prone to freezing after oil has compromised their natural waterproofing.
Conducted in the 1980s and 1990s, the studies also represent an "old paradigm" of bird rehabilitation, Warnock said. More recent work contradicts their conclusions of poor survival rates, he added.
For instance, a January 2009 study published in the African Journal of Marine Science said that only 27 percent of oil-rescued penguins had been unable to breed following their release—a relatively low rate.
And other recent studies found that, in the United States, 40 to 60 percent of some species of rehabilitated birds had survived after release, thanks to improved treatment, according to Roger Helm, chief of environmental quality for the U.S. Fish and Wildlife Service (USFWS).
Over the years, rehabilitators have learned—mostly from trial and error—how better to care for injured birds, which is particularly important for rare species, Helm added.
But biologist J.V. Remsen is skeptical of the higher survival rates, at least in the context of the Gulf oil spill. That's because the birds may have ingested toxic oil before they ever reach a rescue center.
"If the rehabbers can convince me that 25-50 percent are going to be successfully cleaned and released back into the environment and not die subsequently and painfully from the oil they have ingested, then OK, let's give it a try," said Remsen, ornithologist and professor at the Louisiana State Department of Biological Sciences in Baton Rouge.
But, he said, "emotionally painful as it is, I would be for euthanizing those birds if it can be shown that the probability of them being successfully rehabbed is low."
As of Monday, 594 dead oiled birds and 413 live ones have been collected along the Gulf Coast since the Deepwater Horizon oil rig exploded on April 20, according to the joint federal-industry response team.
Thirty-nine birds have been released back into the wild, some of them to Florida's Pelican Island National Wildlife Refuge, which is currently outside of the oil's trajectory, according to the National Audubon Society.
Emotional Case for Rehabbing Oiled Birds
Of course, the decision to kill or clean is tough to make on mathematics alone.
"The public demands that something be done," the Oiled Wildlife Care Network's Warnock said. "It's heart-wrenching—you see this totally oil-covered animal. The only way you can see that they're alive is that their little eye blinks. That kills me every time."
Added USFWS' Helm, "We have responsibility for the birds, so we make the choice to do rehabilitation."
Saving even a few birds of rare species can make a real difference, said David Mizejewski, a naturalist at the Virginia-based National Wildlife Federation, a conservation nonprofit.
For instance, in the case of the brown pelican—a Gulf native only recently taken off the U.S. endangered species list—"every individual counts," Mizejewski said.
Gulf Oil Toxic to Birds
Oil harms birds in two ways: internally and externally.
Oil-soaked birds vigorously preen their feathers to remove the toxic crude, accidentally ingesting it, which can cause internal ailments.
"Try removing crude oil from your arm with your mouth and not getting any of it into your body," Louisiana State's Remsen said.
"How much damage has already been done [by the time the bird is rescued]? That's the big unknown in all of this rehabilitation."
Externally, oil degrades the birds' waterproofing oils, allowing cold water to touch skin and making the animals vulnerable to hypothermia, especially in cold regions, the Oiled Wildlife Care Network's Warnock said. "It's like surfing in the Northern Pacific—if your wet suit gets a hole, you're going to be cold fast."
Fortunately many of the hard-hit Gulf species, such as brown pelicans and laughing gulls, don't spend much time at sea, making their waterproofing less critical, Warnock pointed out. (Gulf Oil Spill Pictures: Ten Animals at Risk.)
But addressing the external effects is still an especially tricky task right now in the Gulf.
For instance, the Deepwater Horizon crude is especially sticky, which requires workers to clean the birds with more "intense" detergent, which in turn strips more of the birds' waterproofing oils, according to USFWS' Helm.
Conservationists have to wait weeks or even months for the birds' waterproofing to be naturally replenished, further stressing the animals and reducing space for incoming patients, Helm said.
Rescued Birds' Homing Instincts May Backfire
When a bird is rehabilitated, finding locations to release the animal so it won't get re-oiled is "problematic," Helm added.
That's why rehabilitators tend to choose oil-free habitats far away, Louisiana State's Remsen said. Yet many seabirds are "notorious for exceptional homing abilities, even over completely unfamiliar territory and vast distances.
"Many bird biologists would wager that the released birds would head right back where they came from, back into harm's way, especially during breeding season," Remsen said.
There's also the possibility that the birds won't adjust to their new homes, noted the National Wildlife Federation's Mizejewski. "If you're moved 500 miles [about 800 kilometers] away, even if you're following your instincts, you don't know the topography or where to look for food."
There's "no easy solution to clean up this mess," Mizejewski added. "We can't just take a few birds and put them in dish detergent and say we fixed the problem.
"It's a tragic, real example, in our face, [of the fact] that this problem is going to be with us for decades."