BP oil spill.

I have heard various people try to put a price tag on the damage that the BP oil spill has done. How does one estimate the cost of the death of innocent wildlife and the destruction of delicate ecosytems? Does each oil-covered seabird have an estimated price? How much is a dead wetland worth? When I was a kid, one of my favorite places was a local pond. One day, a "developer" filled-in the pond and constructed some houses. To a real estate appraiser the pond probably had no value, but to me the pond was a rare jewel. The destruction that BP has caused cannot  be healed with any amount of money.