Endangered and Threatened Species of the Platte River (2004)Board on Environmental Science and Toxicology
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The Platte River stretches across three states -- Colorado, Wyoming and Nebraska -- and is home to the endangered whooping crane, interior least tern, and pallid sturgeon and the threatened piping plover. The report focuses on Nebraska's central Platte River and examines the current "critical habitat" designations for the piping plover and whooping crane and whether or not they were supported by existing science. The committee found the agencies' decisions were scientifically valid at the time they were made. However, future decisions should be based on newer scientific approaches. Human activities and increased attacks by predators on nests are also contributing to the continuing drop in numbers of piping plovers and interior least terns. The report also finds that other agency decisions, such as habitat-suitability guidelines and instream-flow recommendations were based on valid science.
- Because piping plovers are mobile and able to find alternative nesting sites, changes in habitat may not be as severe as they would be otherwise, but no studies have been conducted to support or reject this hypothesis.
- Current central Platte River habitat conditions adversely affect the likelihood of survival of the piping plover, and, on the basis of available understanding, those conditions have adversely affected the recovery of the piping plover.
- Current habitat conditions on the central Platte River adversely affect the likelihood of survival of the interior least tern in much the same fashion as they affect the likelihood of survival of the piping plover and that on the basis of available information, current habitat conditions on the central Platte River adversely affect the likelihood of recovery of the interior least tern.
- Current habitat conditions on the lower Platte River (downstream of the mouth of the Elkhorn River) do not adversely affect the likelihood of survival and recovery of the pallid sturgeon because that reach of the river appears to retain several habitat characteristics apparently preferred by the species: a braided channel of shifting sandbars and islands; a sandy substrate; relatively warm, turbid waters; and a flow regime that is similar to conditions that were found in the upper Missouri River and its tributaries before the installation of large dams on the Missouri.
- Given available knowledge, current central Platte habitat conditions adversely affect the likelihood of survival of the whooping crane, but to an unknown degree.
- Habitat selection (to the extent that it can be measured) on multiple geographic scales strongly suggests that Nebraska provides important habitat for whooping cranes during their spring migration.
- Regarding the critical understanding and modeling that DOI has used to explain the connections among stream flow, sediment movement, vegetation, and habitats, the committee found that valid science was used when recommendations were made in the past but that future decisions must rely on the use of newer methods and perspectives, particularly the concept of normative flow regimes.
- The committee found numerous gaps in knowledge. Addressing them could substantially improve science and management for the river, its human population, and its threatened and endangered species.
- The committee found that sufficient scientific knowledge and understanding exist and have been used to make informed decisions about the management of water resources, the Platte River, and the threatened and endangered species that use the river as habitat.
- The designation of central Platte River migratory stopover habitat as critical to the species is therefore supported because the birds have specific requirements for roosting areas that include open grassy or sandy areas with few trees, separation from predators by water, and proximity to foraging areas such as wetlands or agricultural areas.
- The designation of central Platte habitat as critical habitat for the piping plover is scientifically supportable. Until the last several years, the central Platte supported substantial suitable habitat for the piping plover, including all primary constituent elements required for successful reproduction by the species.
- Those gaps are mostly related to problems of integration of the various lines of scientific investigation, a focus on highly localized rather than more broadly based ecosystem perspectives, a lack of analysis of basinwide connections, a lack of standardized procedures for data collection among government and private agencies, and lack of understanding of the relative cost effectiveness and distributional consequences of alternative conservation measures.