Hydatid Disease in Boreal Regions

It is the purpose of this paper to review the status of hydatid disease (caused by Echinococcus spp.) in the boreal regions of the world. Its importance has long been recognized in Eurasian countries, but only during recent years have investigators added anything significant to the knowledge of hydatid disease in North America. There is need to disseminate up-to-date information among medical workers in Canada and Alaska, where the disease is endemic in northern regions having a large aboriginal population. Therefore, particular emphasis will be placed on the situation in boreal North America.

Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales

Top predators in the marine environment integrate chemical signals acquired from their prey that reflect both the species consumed and the regions from which the prey were taken. These chemical tracers—stable isotope ratios of carbon and nitrogen; persistent organic pollutant (POP) concentrations, patterns and ratios; and fatty acid profiles—were measured in blubber biopsy samples from North Pacific killer whales (Orcinus orca) (n = 84) and were used to provide further insight into their diet, particularly for the offshore group, about which little dietary information is available. The offshore killer whales were shown to consume prey species that were distinctly different from those of sympatric resident and transient killer whales. In addition, it was confirmed that the offshores forage as far south as California. Thus, these results provide evidence that the offshores belong to a third killer whale ecotype. Resident killer whale populations showed a gradient in stable isotope profiles from west (central Aleutians) to east (Gulf of Alaska) that, in part, can be attributed to a shift from off-shelf to continental shelf-based prey. Finally, stable isotope ratio results, supported by field observations, showed that the diet in spring and summer of eastern Aleutian Island transient killer whales is apparently not composed exclusively of Steller sea lions.

Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales

Top predators in the marine environment integrate chemical signals acquired from their prey that reflect both the species consumed and the regions from which the prey were taken. These chemical tracers—stable isotope ratios of carbon and nitrogen; persistent organic pollutant (POP) concentrations, patterns and ratios; and fatty acid profiles—were measured in blubber biopsy samples from North Pacific killer whales (Orcinus orca) (n = 84) and were used to provide further insight into their diet, particularly for the offshore group, about which little dietary information is available. The offshore killer whales were shown to consume prey species that were distinctly different from those of sympatric resident and transient killer whales. In addition, it was confirmed that the offshores forage as far south as California. Thus, these results provide evidence that the offshores belong to a third killer whale ecotype. Resident killer whale populations showed a gradient in stable isotope profiles from west (central Aleutians) to east (Gulf of Alaska) that, in part, can be attributed to a shift from off-shelf to continental shelf-based prey. Finally, stable isotope ratio results, supported by field observations, showed that the diet in spring and summer of eastern Aleutian Island transient killer whales is apparently not composed exclusively of Steller sea lions.

Prairie Dog Empire: A Saga of the Shortgrass Prairie

For hundreds of years black-tailed prairie dogs inhabited the Great Plains by the millions, improving the grazing for bison and pronghorn antelope, digging escape holes and homes for burrowing owls and rodents, and serving as prey for badgers, coyotes, hawks, and bobcats. This book by the renowned naturalist and writer Paul A. Johnsgard tells the complex biological and environmental story of the western Great Plains under the prairie dog’s reign—and then under a brief but devastating century of human dominion. An indispensable and highly readable introduction to the ecosystem of the shortgrass prairie, Prairie Dog Empire describes in clear and detailed terms the habitat and habits of black-tailed prairie dogs; their subsistence, seasonal behavior, and the makeup of their vast colonies; and the ways in which their “towns” transform the surrounding terrain—for better or worse. Johnsgard recounts how this terrain was in turn transformed over the past century by the destruction of prairie dogs and their grassland habitats, together with the removal of the bison and their replacement with domestic livestock. A disturbing look at profound ecological alterations in the environment, this book also offers a rare and invaluable close-up view of the rich history and threatened future of the creature once considered the “keystone” species of the western plains. Included are maps, drawings, and listings of more than two hundred natural grassland preserves where many of the region’s native plants and animals may still be seen and studied. This excerpt includes the Preface and Chapter 1, "The Western Shortgrass Prairie: A Brief History."

An Intercomparison of Regional Atmospheric Circulation and the Melt Season Loss of Arctic Snow Cover and Sea Ice Extent Across the Land-Ocean Boundary

This study is designed to compare the monthly continental snow cover and sea ice extent loss in the Arctic with regional atmospheric conditions including: mean sea level pressure, 925 hPa air temperature, and mean wind direction among others during the melt season (March-August) over the 29-year study period 1979-2007. Little research has gone into studying the concurrent variations in the annual loss of continental snow cover and sea ice extent across the land-ocean boundary, since these data are largely stored in incompatible formats. However, the analysis of these data, averaged spatially over three autonomous study regions located in Siberia, North America, and Western Russia, reveals a distinct difference in the response of snow and sea ice to the atmospheric forcing. On average, sea ice extent is lost earlier in the year, in May, than snow cover, in June, although Arctic sea ice is located farther north than continental snow in all three study regions. Once the loss of snow and ice extent begins, snow cover is completely removed sooner than sea ice extent, even though ice loss begins earlier in the melt season. Further, the analysis of the atmospheric conditions surrounding loss of snow and ice cover over the independent study regions indicates that conditions of cool temperatures with strong northeasterly winds in the later melt season months are effective at removing sea ice cover, likely through ice divergence, as are warmer temperatures via southerly winds directly forcing melt. The results of this study set the framework for further analysis of the direct influence of snow cover loss on later melt season sea ice extents and the predictability of snow and sea ice extent responses to modeled future climate conditions