1. ECOSYSTEM (MIS)MANAGEMENT. The ESA encourages selective review of individual species needs, even though nature pits species needs against one another. Furthermore, the ESA's single-species focus detracts from efforts to achieve environmental restoration and ecosystem management.
2. SCIENTIFIC UNCERTAINTY: While the ESA requires consideration of the "best available science," sometimes the best is not enough, forcing decisions under great uncertainty. The ESA, however, is generally proscriptive, regulatory, and absolute; as a result, it insufficiently allows for adaptive management.
3. LITIGATION: ESA implementation is at the mercy of the attorneys. Cases involving one listed species can serve as a proxy for hidden agendas, especially land use disputes, and regardless of actual species needs, litigation and judicial orders set agency priorities. In the end, realistic solutions disappear amidst court-filings, fundraising, and rhetoric.
4. PRIVATE LANDS: Up to 80% of ESA-listed species habitat is on privately owned lands. While the ESA can place reasonable restrictions on private property rights, there are limits. But the best alternatives have limits too, such as Federal land acquisition and the highly controversial "God Squad" exemptions.
5. FUNDING: Protecting species is expensive, but resources appropriated by Congress are limited. An overburdened handful of federal agency biologists cannot keep pace with the ESA's procedural burdens, nor court-ordered deadlines (see #3 above). Provisions requiring agencies to pay attorney's fees to victorious litigators -- who challenge the hastily written documents prepared by overworked bureaucrats -- simply exacerbate the problem.