70 / Chapter 3
Society for the Prevention of Cruelty to Animals set up additional
emergency cleaning stations in the area, but the efforts were mostly
in vain. Of the 7,849 birds rescued, only 450 remained alive by mid-
April, and most of these died soon after that. Less than 1 percent
survived long enough to be released. Estimates on the total number
of birds killed range from 30,000 to 75,000. They died from the oil
and the dispersants used to break it up but also from improper han-
dling and from exposure to the harsh, solvent-based cleaners in use
at the time. Marine species such as limpets, barnacles, and shellfi sh
also suffered widespread mortality and a rare species of hermit crab
has disappeared from the area since the spill.^30
What Does Oil Do to Birds
and Mammals?
Oil causes suffering to birds and mammals through ingestion and
physical contact, most often in combination. Birds stay warm and
waterproof through the complex arrangement of their feathers like
shingles on a roof.^31 Each feather consists of a stiff but hollow cen-
tral shaft that runs its entire length. Vanes extend to each side of
the shaft, and a system of barbs makes up the vane. The barbs
have microscopic hook-and-loop structures, called barbicels, that
keep the feather together. When a feather is out of place, only birds
know how to repair it through preening. The urge to preen over-
rides all other instincts, including the need to eat and drink.
The structure of plumage creates a wind- and waterproof bar-
rier that helps the bird stay afl oat. Even a tiny amount of oil can
compromise a bird’s ability to remain insulated and waterproof.^32
Oil-soaked feathers cannot trap air to keep the bird warm, putting
the bird at risk for hypothermia. The feathers mat together and lose
their ability to provide waterproofi ng. Moreover, the birds try to
remove the oil and restore the integrity of the feathers by preening.
Through preening they ingest oil, which causes extensive internal
damage. Oil-soaked birds attempt to get warm by seeking shelter on
land, where they become vulnerable to predators or die from mal-