An estimated 300-400 pelicans reported from New Orleans have been harmed by BP's [NYSE:BP] oil spill, marking another escalation in wildlife devastation caused by the pipeline in the Gulf of Mexico, according to The Washington Post.

The government only counts oiled covered birds collected for rehabilitation or found dead for use in the spill investigation as evidence. There are many nesting areas in the Gulf and since not all birds can be collected an counted, the scope of the damage could be significantly underestimated.

Roughly 3,000 killed or oil-smeared birds have been collected by wildlife agencies since BP's Deepwater Horizon drilling rig exploded and sank on April 20, killing 11 workers.

The difficulty, according to Lisa Williams, a U.S. Fish and Wildlife Service biologist, is that attempting to rescue all of the oiled birds in the Gulf and the coastal islands, particularly Raccoon Island, can disrupt their nesting habits and flush the colonies, causing the birds to abandon their young.

"We don't want to cause more harm than good," Williams said.