Oil Spill Impacts On Birds

Brown Pelican

The Gulf oil disaster put shorebirds, waterfowl and marsh birds at great risk.

How Many Birds Were Affected by the Gulf Oil Disaster?

During the six months after the explosion of the Deepwater Horizon, more than 7,000 birds were collected in the spill area, of which nearly 3,000 (about 40%) showed visible signs of oiling.

The following map animation shows when and where injured and dead birds were picked up after the oil spill.

Where Did These Numbers Come From?

This map is based on the consolidated numbers of birds that were reported to the U.S. Fish and Wildlife Service. These records were used to map the animals collected each day. There are minor variations from official government records in the total number of animals shown, for several reasons. The date marked on each map is the date the data were posted online by the government. Since then, a few additional animals have been collected. Furthermore, due to the time needed to process and verify data, animals collected just a week to 10 days prior to the date of data release may have not yet been recorded.

Was the Oil Spill the Cause of All These Deaths and Injuries?

These numbers include all birds collected in the oil spill area. While the actual cause of death has yet to be determined for most of the animals, it is clear that a large proportion of the deaths and injuries were related to the oil spill, as the number of animals collected--especially the birds and sea turtles--was far beyond what is usually found in that area.

Why is the Total Number of Birds Collected Lower than What the U.S. Fish and Wildlife Service has Reported?

Each bird collected (dead or alive) was recorded and entered in the USFWS database. According to USFWS, some of the collected live birds later died in captivity and were entered into the database a second time. As a result, USFWS says that "approximately 10 percent of the grand total represents live birds that later died, so those individuals are counted twice." Prior to making our maps showing the accumulation of birds collected, we corrected the data set so that birds collected alive that later died were counted only once, and reported as dead birds.

Will the Total Number of Birds Affected Ever Be Known?

No. Although the birds tallied in these maps may include some that were injured or died of causes unrelated to the spill, given the vastness of the Gulf others surely disappeared without being observed or collected by authorities. Scientists are also concerned about other impacts on birds that can be even more difficult to discern, ranging from the sublethal effects of oil exposure on reproduction and other physiological functions, to the loss of important foraging or nesting habitat.

What Bird Species Were Hit Hardest by the Gulf Oil Disaster?

The U.S. Fish and Wildlife Service released data around the species impacted by the Gulf oil disaster in September, thanks in part to a Freedom of Information Act request submitted by the National Wildlife Federation.

As of May 12, 2011 the top bird species collected in the spill area were:

  • Laughing gull - 2,981
  • Brown pelican - 826
  • Northern gannet - 475
  • Royal tern - 289
  • Black skimmer - 253

U.S. Fish and Wildlife Service Bird Impact Data >>

How Does Oil Affect Birds?

Oil causes birds' feathers to mat and separate, causing the bird to lose its buoyancy and the ability to regulate body temperature. Contact with oil on their skin or face can cause skin and eye lesions.

Birds need to preen their feathers to keep themselves warm and dry, remove parasites and keep their feathers in good shape. Birds may ingest oil while preening their feathers or by eating contaminated food. Internal exposure to oil can lead to ulcers, pneumonia, liver damage, and other life-threatening conditions.

Migratory Birds and the Gulf Coast Region

The Gulf Coast is a critical stopover point or destination for many migratory species. Bird banding data from the past 50 years shows that birds migrating either through or to the Gulf region were also recorded throughout North America.

Check out these U.S. Geological Survey maps of how banded birds traveled through the Gulf. >>

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Five Years and Counting, a report by the National Wildlife Federation