The U.S. Department of Defense would be permanently exempted from an international law protecting more than 850 species of migratory birds, under a tentative agreement reached between negotiators from the House and Senate and disclosed by environmental groups yesterday. The negotiations began after the Bush administration complained that the 1918 Migratory Bird Treaty Act interfered with military training exercises. The agreement would effectively allow the incidental bombing of the habitat of hundreds of thousands of migratory birds, including endangered species, on 25 million acres of military-controlled land. However, the DOD would have to examine ways to minimize the impact of military exercises on the birds. The treaty is just one of several environmental laws from which the military has sought exemptions in the aftermath of Sept. 11, 2001. Many environmentalists and some lawmakers feel the trend has gotten out of hand: “Exempting our military from the MBTA … endangers our wildlife heritage and compromises our international treaty obligations,” said Rep. Nick Rahall (D-W.Va.).