As of 31 May, the official toll on birds in the catastrophic Deepwater Horizon well blowout stands at 568, which includes the 74 birds who have been rescued and brought into care at one of the four rehabilitation facilities set up along the north Gulf coast.
     Of the 74 birds, which the report does not break down by species, 57 have been rescued in Louisiana,  closest to the gushing well, and hardest hit by oil. 1 bird has been brought into the Mississippi facility, and the rest are split between Alabama and Florida. So far, 24 have been released, hundreds of miles away, near Tampa as well as on the East coast.

First victims of oil spill released in Pelican Island National Wildlife Refuge

     The daily report from the US Fish and Wildlife Service breaks the two categories of live and dead down into visibly oiled, no visible oil, and pending. Pending describes those animals whose oiling is not obvious in the field, according to information gotten from the Deepwater Horizon Response website, and is meant to be resolved into either of the other two categories in the clinic, or lab. 69 of 74, or 93%, of the live birds rescued were visibly oiled.
      Strikingly, among the 494 dead birds collected, only 29, or 6%, were reported as visibly oiled, while 70% (348) of these birds were reported as not visibly oiled. The percentage of non visibly oiled birds may climb due to the 110 ‘pending’ cases of the 186 dead birds found in Louisiana.
      Also worth noting, while Louisiana far outpaces the other three states for live oiled birds captured and brought into care, dead birds have been found more evenly distributed. In Alabama, 137 dead birds have been collected, with only 5 of them visibly oiled. 133 dead birds have been collected in Florida, 7 of them visibly oiled. In Louisiana, besides the 110 pending cases, 15 visibly oiled birds have been collected along with 61 non-visibly oiled birds, while only 2 of the 38 dead birds collected in Mississippi are reported as visibly oiled.
      
    Oil can kill birds in a number of ways. What we see most often, however are birds visibly oiled (with perhaps only a small amount, but visible) that have caused a typically water-dwelling bird to come to shore due to a loss of waterproofing.  Oil violates the integrity of an aquatic bird’s feather structure allowing water to penetrate to the their skin. If a bird is to maintain a normal body temperature that can range from 102-106˚F (approx 40-42˚C) the critical function of feathers as insulation and waterproofing cannot be impaired.
     In other words, oiled aquatic birds become cold and wet. They have to get out.  However, adapted to life on water, many aquatic birds are wholly unsuited for land, and are highly vulnerable when beached.  Although they might find relief from the cold, on shore things only get worse. By actively preening, all birds keep their feathers clean and functional. When oiled,  preening leads to ingestion of oil and the eventual poisoning.
Eared grebes beached afer Cosco Busan fuel oil spill in San Francisco Bay 11/07
 
Without intervention by a rehabilitator, a bird in this situation is going to die. The greater the extent of oiling, the more quickly comes death, but almost any amount of oiling can kill.
     While the internal effects of oil do kill birds, these effects are hard to come by without external oiling present – which leads to the question: why is such a high percentage of the dead birds not visibly oiled?
     The USFWS report offers no conclusions and leaves many significant questions unasked and unanswered. Why are there so many non-oiled dead birds in the spill zone? Have any tests been done to determine the cause of death? What species are being affected? How many oiled birds are being observed in the field? In a region so rich in aquatic birds, in an oil spill of such magnitude, why have so few birds been brought into care? In the response to the devastation that this spill is wreaking on the Gulf, are all hands really on deck? Given the unprecedented quantities and highly controversial use of dispersants such as Corexit 9500 it seems these questions deserve public answers.