Effects of Arctic Alaska Oil Development on Brant and Snow Geese

Black brant (Branta bernicla nigricans) and lesser snow geese (Chen c. caerulescens) breeding in and near arctic Alaska oil fields could be affected by oil development actions such as releases of contaminants, alteration of tundra surfaces, creation of impoundments, and human activities. These actions could affect geese directly (e.g., through oil spills) or indirectly (e.g., by altering food supplies or predator populations). Studies to date indicate no changes in the distribution, abundance, or reproduction of these geese that clearly can be attributed to development; rather, their numbers and recruitment have responded in the oil fields, as elsewhere, mainly to weather and predation. When snowmelt in spring is later than usual, the birds postpone or forego nesting, with consequent diminishment in recruitment. Predation by arctic foxes (Alopex lagopus), glaucous gulls (Larus hyperboreus), and grizzly bears (Ursus arctos) sometimes causes substantial losses of eggs and young, and predation by ravens (Corvus corax) has also been observed. Development-related changes in weather (microclimate) and loss of feeding habitat have involved small percentages of the total areas traditionally used, and populations of the birds probably have not been affected by these changes. Some studies and observations suggest that development has elevated local populations of some predators, but whether the level of predation on geese has in consequence risen above that which would have occurred in the absence of development is unknown; further investigation of this mechanism of potential impact is recommended.La bernache noire (Branta bernicla nigricans) et la petite oie des neiges (Chen c. caerulescens) nichant dans les champs pétrolifères de l'Alaska ou à proximité pourraient être affectées par des actes reliés à l'exploitation pétrolière, tels que le déversement d'agents de pollution, les modifications à la toundra de surface, la création de bassins, et par l'activité humaine. Ces interventions pourraient affecter les oies de façon directe (p. ex., par le biais de déversements de pétrole) ou indirecte (p. ex., en modifiant l'approvisionnement alimentaire ou les populations de prédateurs). Jusqu'à l'heure actuelle, les études ne montrent pas de changements dans la distribution, l'abondance ou la reproduction de ces oies, dont la cause puisse être clairement attribuée à l'exploitation; dans les champs pétrolifères, le nombre d'oies et leur augmentation ont surtout réagi, comme ailleurs, au climat et à la prédation. Quand la fonte des neiges printanière a lieu plus tard que d'habitude, les oiseaux retardent la ponte ou s'abstiennent de pondre, ce qui entraîne moins d'augmentation. La prédation par le renard arctique (Alopex lagopus), le goéland bourgmestre (Larus hyperboreus) et le grizzli (Ursus arctos) entraîne parfois d'importantes pertes d'oeufs et d'oisons, et on a également observé des cas de prédation par le corbeau (Corvus corax). Des modifications climatiques (microclimat) reliées à l'exploitation et la perte d'aires d'alimentation ne concernent qu'un faible pourcentage du total des zones utilisées traditionnellement, et les populations d'oiseaux n'ont probablement pas été affectées par ces changements. Quelques études et observations suggèrent que la mise en valeur a fait augmenter les populations locales de certains prédateurs, mais on ne sait pas si le niveau de prédation de l'oie qui en a résulté était plus élevé qu'il ne l'aurait été en l'absence de la mise en valeur; on recommande que le mécanisme de ces retombées potentielles soit étudié plus à fond

Managing Bison to Restore Biodiversity

Prior to their demise in the late 1800s, bison coexisted with and helped sustain a diverse and spectacular assemblage of animals and plant communities on the Great Plains. Bison, in concert with fire, exerted strong control on the structure of the vegetation by grazing, trampling, and wallowing. The changes in the vegetation induced changes in many animal populations. These impacts, coupled with the bison\u27s role as the major converter of grass to meat, so greatly affected other species that some have called bison a keystone species in the Great Plains ecosystem. The black-tailed prairie dog, dependent on bison grazing over a large part of the Great Plains, amplified the keystone influence of bison by its own grazing and burrowing activities and its utility as prey. Although modern bison-growing practices usually will preclude restoration of the large predators and scavengers that once were a part of the great faunal spectacle, other species can return, often even on small acreages. Maintenance of a habitat mosaic is the key to restoring some of the original biodiversity lost to the historic pursuit of single species pastoralism

Book Review of \u3ci\u3eGreat Plains: America’s Lingering Wild\u3c/i\u3e by Michael Forsberg.

Michael Forsberg’s magnificent photos of land, animals, and people compelled me initially to turn page after page of Great Plains. The wonderful color images pulled me into the initial historical overview and chapter introductions by historical geographer David Wishart, field journal anecdotes by Forsberg himself, and the intensely personal essays by wildlife biologist and rancher Dan O’Brien. Ted Kooser’s foreword poetically set the tone for both the photography and the text. Forsberg and O’Brien present short pieces up front to introduce the book. Then comes a sweeping historical overview by Wishart, telling in about ten text pages and numerous historical photos how settlers from Europe in less than a century displaced Native hunters and lifeways across this vast land. The main body of the book—containing sections on the Northern Plains, the Southern Plains, and the tallgrass prairies—follows Wishart’s overview

Migrations of Grassland Communities and Grazing Philosophies in the Great Plains: A Review and Implications for Management

Ecologists commonly separate Great Plains grasslands communities into types based on grass height: shortgrass prairie, mixed-grass prairie, and tallgrass prairie. Grass height correlates directly with precipitation and thus lessens with distance westward and with drought. Grass height correlates inversely with grazing intensity and thus shortgrasses expand eastward when grazing pressures are great and shrink westward when grazing pressures relax. Evidence about past distributions of shortgrasses, coupled with the prehistoric and historic abundances of large grazers and the black-tailed prairie dog (a shortgrass indicator), suggest a far-eastward occurrence of shortgrass prairie in the late Pleistocene (despite a relatively wet climate), a shrinkage westward by late prehistoric and early historic times, and a farther shift westward in response to the bison\u27s demise in the 19th century. After cattle arrived in the late 1800s, shortgrass prairie expanded and contracted depending on the prevailing grazing philosophies, resulting grazing intensities, and periodic drought. Currently, taller grasses have prevailed for over a half century, and shortgrass prairie may be more restricted than it has been for millennia, because of a grazing philosophy that promotes moderate grazing. An emerging change in grazing philosophy may presage a gradual return of heavier grazing and another expansion eastward of the shortgrass prairie. Such an expansion, particularly if accompanied by grazing regimes patterned on early historic and prehistoric grazing, may enhance biodiversity, the stability of some soils, and under some circumstances, economic returns from ranching

Movements of immature mourning doves, Zenaidura macroura marginella, in southern Arizona

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Ecology of the desert mule deer, Odocoileus hemionus Crooki Mearns, in southeastern Arizona

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