No abstract

Because of its use as a nuclear materials production area, the 800-kin 2 sagebrush steppe of the Columbia River Plain in Washington State has functioned as a quasinatural area protected from livestock grazing and agricultural development since 1944. Alien vegetation and animals have invaded the eastern Washington region in the past century and are currently represented in the Columbia River Plain. Investigations were undertaken to evaluate the distribution of alien species, particularly vegetation, and their relationships to other flora and fauna in this region.Recently disturbed areas were dominated by the alien annuals Russian thistle Salsola kali, tumble mustard Sisymbrium altissimum, prickly lettuce Lactuca serriola, and bur ragweed Ambrosia acanthicarpa. Oldfield habitats were composed almost entirely of the alien annual cheatgrass Bromus tectorum. Alien vegetation also comprised a portion of the flora in habitats that had not been disturbed or grazed by cattle in the past. Cheatgrass and spring whitlow-grass Draba verna were able to set seed in undisturbed habitats, whereas Russian thistle and tumble mustard seldom did. These two species continue as components of undisturbed habitat primarily through seed dispersal from disturbed sites.Old-fieM habitats support a depauperate fauna compared to undisturbed sagebrush steppe vegetation. Shrubnesting birds such as the sage sparrow Amphispiza belli were absent from old fields, and even ground-nesting species were found in abnormally low densities. Old fields supported relatively few mammal species, in part as a result of poor food supplies. Alien birds, the rock dove Columba livia and the European starling Sturnus vulgaris, visited undisturbed habitat, but did not nest there.No alien mammals were found in undisturbed sagebrush steppe vegetation; the only alien mammals found in the area, the house mouse Mus musculus and Norway rat Rattus norvegicus, being limited to riparian areas and the vicinity of buildings.Alien taxa are likely to remain a component of any quasi-natural area in the sagebrush steppe ecoregion.Conservation 0006-3207/94/$07.00 © 1994 Elsevier Science Limited, England. Printed in Great Britain Human disturbance need not be spatially extensive to maintain alien plants within undisturbed communities. Successional patterns after land disturbance produce conditions unfavorable for native fauna, but have not enhanced the distribution of alien fauna.

The objective of this report is to provide a comprehensive source of the best available information on Hanford Site sensitive and critical habitats and plants and animals of importance or special status, as defined in the "Hartford Site Baseline Risk Assessment Methodology" (DOE 1993a). " The information can be used in environmental evaluations for baseline risk assessments of the Site to determine the environmental effects of remedial actions and provide a basis for assessing the cumulative impacts of multiple actions. Pacific Northwest Laboratory and Westinghouse Hanford Company worked together to compile the information, which has been collected through basic research programs, monitoring programs, and educational endeavors. In this report, sensitive habitats include areas known to be used by threatened, endangered, or sensitive plant or animal species, wetlands, preserves and refuges, and other sensitive habitats outlined in the Hanford Site Baseline Risk Assessment Methodology. Potentially important species for risk assessment and species of special concern with regard to their status as threatened, endangered, or sensitive are described, and potential habitats for these species identified. The following primary habitat types for the Hanford Site are shown on maps and described according to vegetation association and topography: i vi 2.I Generalized Soils Map fortheHanford Site ..

Age-related differences in the foraging efficiency of piscivorous birds may be the results of differences in foraging skill, patch usage, or both. Brown pelicans were observed while foraging around a small Caribbean island. Areas where the birds fed were subdivided into small, homogeneous subunits (patches), and the bird's foraging success and patch use were noted and analyzed using multivariate techniques. Adult birds were found to be better at capturing prey under all conditions than were juveniles, but the differences were small in some patches. The density of prey and the birds' foraging success influenced the foraging efforts of adult and juvenile pelicans to similar degrees. Both age groups utilized local enhancement in their foraging, but such behavior augmented the foraging success only of juvenile birds. Both age groups often fed in patches where their foraging success was quite low. Such behaviour was much more costly for juvenile than for adult pelicans.

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