Iconic sagebrush ecosystems of the American West are threatened by larger and more frequent wildfires that can kill sagebrush and facilitate invasion by annual grasses, creating a cycle that alters sagebrush ecosystem recovery post disturbance. Thwarting this accelerated grass–fire cycle is at the forefront of current national conservation efforts, yet its impacts on wildlife populations inhabiting these ecosystems have not been quantified rigorously. Within a Bayesian framework, we modeled 30 y of wildfire and climatic effects on population rates of change of a sagebrush-obligate species, the greater sage-grouse, across the Great Basin of western North America. Importantly, our modeling also accounted for variation in sagebrush recovery time post fire as determined by underlying soil properties that influence ecosystem resilience to disturbance and resistance to invasion. Our results demonstrate that the cumulative loss of sagebrush to direct and indirect effects of wildfire has contributed strongly to declining sage-grouse populations over the past 30 y at large spatial scales. Moreover, long-lasting effects from wildfire nullified pulses of sage-grouse population growth that typically follow years of higher precipitation. If wildfire trends continue unabated, model projections indicate sage-grouse populations will be reduced to 43% of their current numbers over the next three decades. Our results provide a timely example of how altered fire regimes are disrupting recovery of sagebrush ecosystems and leading to substantial declines of a widespread indicator species. Accordingly, we present scenario-based stochastic projections to inform conservation actions that may help offset the adverse effects of wildfire on sage-grouse and other wildlife populations.
We used satellite transmitters to track the 2000–2003 spring migrations of adult female Northern Pintails (Anas acuta L., 1758) from California's Central Valley, USA. PTT-tagged Pintails departed during late February to mid-March, and 77%–87% stopped first in the region of south-central Oregon, extreme northwestern Nevada, and northeastern California (SONEC). Subsequently, most Pintails used migration strategies characterized by the length of stay in SONEC and subsequent destinations: (i) extended stay in SONEC, migrated late April to early May directly to Alaska over the Pacific Ocean (7%–23% annually); (ii) same timing as in i, but flew to Alaska along the Pacific Coast using stopovers (0%–28% annually); (iii) moderate period in SONEC, migrated late March to mid-April directly primarily to southern Alberta in Prairie Canada (17%–39% annually), with many moving to northern Canada or Alaska; or (iv) short period in SONEC, migrated early to late March to Prairie Canada via stopovers primarily in southern Idaho and western Montana (32%–50% annually), with some moving to northern Canada or Alaska. Pintails that bypassed SONEC used these same strategies or moved easterly. Pintails modified migration strategies relative to record cold temperatures and wetland abundance in the mid-continent prairie region.
The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection of more than 200 standardized terrestrial and marine animal tracking studies from 1991 to the present. The AAMA supports public data discovery, preserves fundamental baseline data for the future, and facilitates efficient, collaborative data analysis. With AAMA-based case studies, we document climatic influences on the migration phenology of eagles, geographic differences in the adaptive response of caribou reproductive phenology to climate change, and species-specific changes in terrestrial mammal movement rates in response to increasing temperature.
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