Fish and Wildlife

Since the completion of Glen Canyon Dam in 1963, the amount of sand supplied to Grand Canyon National Park has been reduced by more than 90 percent. The Paria River, a tributary to the Colorado River 15 miles downstream from the dam, is now the single most important supplier of sand to the Colorado River within the Park. This large reduction in sand supply has resulted in substantial decrease in...

In 1996, the Secretary of the Interior signed a formal decision altering the historical flows from Glen Canyon Dam and establishing the Glen Canyon Dam Adaptive Management Program (GCDAMP). In the context of the management of Glen Canyon Dam, adaptive management was selected to create a process whereby “the effects of dam operations on downstream resources would be assessed and the results of...

Desert bighorn sheep populations in the southwestern United States are subject to non-native disease outbreaks, habitat loss, and genetic isolation that can threaten their long-term sustainability. In some regions of the southwest, mountain lion predation on desert bighorn sheep has been found to be the primary source of mortality. Grand Canyon National Park is home to one of the largest desert...

As a result of growing human populations, many areas have become urbanized and highly developed, leaving natural native habitats fragmented across the landscape. In southern California many of the remaining patches on native habitat are bisected by major, multi-lane highway systems. Threats to the long-term sustainability of native wildlife populations include genetic isolation, where inbreeding...

The desert Southwest is experiencing rapid development of utility-scale solar and wind energy facilities. Although clean renewable energy has environmental benefits, it can also have negative impacts on wildlife and their habitats. Understanding those impacts and effectively mitigating them is a major goal of industry and resource managers. One species of particular concern is Agassiz’s desert...

Big sagebrush ecosystems are a major component of landscapes in the western U.S. and provide vital habitat to a wide array of wildlife species. However, big sagebrush ecosystems have been dramatically impacted by disturbances in the past several decades. This collaborative research between USGS and the University of Wyoming focuses on understanding how climatic and soil conditions influence big...

Information on disease presence can be of use to natural resource managers, especially in areas supporting threatened and endangered species that occur coincidentally with species that are suspected vectors for disease. A general sense of pathogen presence (or absence) can inform management directed at threatened and endangered species, especially in regions where disease is suspected to have...

Agassiz’s desert tortoises ( Gopherus agassizii ) approach the southern edge of their mostly Mojave Desert range near Joshua Tree National Park. Modern desert tortoise research started in the Park in 1978 when the first tortoise population census was conducted on a one square mile area in the Pinto Basin known as the “Barrow Plot.” U.S. Geological Survey research began at the plot in 1997 and...

Aquatic insects live in the water as larvae most of their lives, then emerge onto land for a brief period as winged adults. Sampling these emerged adults on land is therefore a useful tool for understanding the condition of the aquatic insect population that is in the water, particularly in large rivers where sampling the larvae on the river bed is impractical. Our group uses a variety of methods...