Environmental Predictors of Human West Nile Virus Infections, Colorado

To determine whether environmental surveillance of West Nile virus–positive dead birds, mosquito pools, equines, and sentinel chickens helped predict human cases in metropolitan Denver, Colorado, during 2003, we analyzed human surveillance data and environmental data. Birds successfully predicted the highest proportion of human cases, followed by mosquito pools, and equines

Temporal rate of change in location (± 95% credible intervals) from median line of the whooping crane migration corridor based on opportunistic sightings and telemetry locations, 1942–2016.

<p>Estimated rate of shift at 13 analysis windows for locations that were west (A) and east (C) of the median line of the migration corridor. Open circles represent estimates where 95% credible intervals included 0 and closed symbols represent estimates where 95% credible intervals do not include 0. Predicted distance of locations along the migration corridor during 1980 (black circles and solid line) and 2014 (gray triangles and line) west (B) and east (D) of the corridor center. The gray dashed line represents the migration corridor median line and numbers at each point identify centers of 13 300-km windows used in analyses.</p

Temporal change in center and width of the whooping crane migration corridor based on opportunistic sightings and telemetry locations, 1942–2016.

<p>Estimated average east-west shift in 13 300-km analysis windows along the migration corridor (A, km/year). Open circles represent estimates where the 95% credible intervals included 0 and closed symbols represent estimates where the 95% credible intervals do not include 0. Positive values reflect eastward change, whereas negative values reflect westward movement. Predicted average locations (B) along the migration corridor during 1980 (black circles and line) and 2014 (gray triangles and line). Numbers at each point identify centers of 13 300-km windows used in analyses. Annual average change and 95% credible intervals in distance of locations relative to median line of the whooping crane migration corridor (C).</p

Delineating and identifying long-term changes in the whooping crane (<i>Grus americana</i>) migration corridor

<div><p>Defining and identifying changes to seasonal ranges of migratory species is required for effective conservation. Historic sightings of migrating whooping cranes (<i>Grus americana</i>) have served as sole source of information to define a migration corridor in the Great Plains of North America (i.e., Canadian Prairies and United States Great Plains) for this endangered species. We updated this effort using past opportunistic sightings from 1942–2016 (<i>n</i> = 5,055) and more recent (2010–2016) location data from 58 telemetered birds (<i>n</i> = 4,423) to delineate migration corridors that included 50%, 75%, and 95% core areas. All migration corridors were well defined and relatively compact, with the 95% core corridor averaging 294 km wide, although it varied approximately ±40% in width from 170 km in central Texas to 407 km at the international border of the United States and Canada. Based on historic sightings and telemetry locations, we detected easterly movements in locations over time, primarily due to locations west of the median shifting east. This shift occurred from northern Oklahoma to central Saskatchewan at an average rate of 1.2 km/year (0.3–2.8 km/year). Associated with this directional shift was a decrease in distance of locations from the median in the same region averaging -0.7 km/year (-0.3–-1.3 km/year), suggesting a modest narrowing of the migration corridor. Changes in the corridor over the past 8 decades suggest that agencies and organizations interested in recovery of this species may need to modify where conservation and recovery actions occur. Whooping cranes showed apparent plasticity in their migratory behavior, which likely has been necessary for persistence of a wetland-dependent species migrating through the drought-prone Great Plains. Behavioral flexibility will be useful for whooping cranes to continue recovery in a future of uncertain climate and land use changes throughout their annual range.</p></div

Migration corridors for whooping cranes of the Aransas-Wood Buffalo population, delineating 50% core (A), 75% core (B), and 95% core migration areas, with 95% confidence bands.

<p>Migration corridors for whooping cranes of the Aransas-Wood Buffalo population, delineating 50% core (A), 75% core (B), and 95% core migration areas, with 95% confidence bands.</p