A single helicase amino acid substitution, NS3-T249P, has been shown to increase viremia magnitude/mortality in American crows (AMCRs) following West Nile virus (WNV) infection. Lineage/intra-lineage geographic variants exhibit consistent amino acid polymorphisms at this locus; however, the majority of WNV isolates associated with recent outbreaks reported worldwide have a proline at the NS3-249 residue. In order to evaluate the impact of NS3-249 variants on avian and mammalian virulence, multiple amino acid substitutions were engineered into a WNV infectious cDNA (NY99; NS3-249P) and the resulting viruses inoculated into AMCRs, house sparrows (HOSPs) and mice. Differential viremia profiles were observed between mutant viruses in the two bird species; however, the NS3-249P virus produced the highest mean peak viral loads in both avian models. In contrast, this avian modulating virulence determinant had no effect on LD50 or the neurovirulence phenotype in the murine model. Recombinant helicase proteins demonstrated variable helicase and ATPase activities; however, differences did not correlate with avian or murine viremia phenotypes. These in vitro and in vivo data indicate that avian-specific phenotypes are modulated by critical viral-host protein interactions involving the NS3-249 residue that directly influence transmission efficiency and therefore the magnitude of WNV epizootics in nature.

Spatial and temporal closures of anthropogenic activities are a common management strategy to increase waterfowl usage of an area. However, empirical evidence, specifically how individual waterfowl respond to disturbance, is lacking to support their efficacy. We exposed radiomarked mallards (Anas platyrhynchos) to walk-in, shooting, or no disturbance along the South Platte River corridor in Colorado, USA, from September to February during 2006-2007 and 2007-2008. Mallards exposed to shooting disturbance had greater mean flight distance after disturbance (FDAD) during September-November (4.58 km, 95% CI 5 3.55-5.62) than December-February (3.04 km, 95% CI 5 2.51-3.58) and were 35% and 17% greater than mean FDAD of mallards exposed to walk-in disturbance, respectively. Walk-in and shooting disturbance had a similar effect on return rates, and disturbed mallards had higher (0.09-0.41) movement probabilities away from and lower (0.15-0.20) probabilities of returning to treatment locations than controls. Probability of presence of disturbed mallards was 37% lower than controls during the daytime but was equal at night. Mallards exposed to walk-in (0.38 [95% CI 5 0.30-0.46]) and shooting (0.23 [95% CI 5 0.17-0.30] disturbance had low return rates the first afternoon after a disturbance compared to controls (0.71 [95% CI 5 0.65-0.77]). A high proportion of mallards exposed to walk-in (0.75 [95% CI 5 0.67-0.83]) and shooting (0.70 [95% CI 5 0.64-0.76]) disturbance returned to treatment locations in M 1 day. Managers may be able to more effectively manage disturbance regimes by 1) accounting for surrounding lands within ,10 km, especially lands within ,5 km, 2) being conscientious when establishing regulations that will affect levels of disturbance 1-2 days after a previous disturbance, and 3) considering shooting and walking disturbance equally for refuge design.

Abstract. A West Nile virus (WNV) isolate from Mexico (TM171-03) and BIRD1153, a unique genotype from Texas, have exhibited reduced murine neuroinvasive phenotypes. To determine if murine neuroinvasive capacity equates to avian virulence potential, American crow ( Corvus brachyrhynchos ) and house sparrows ( Passer domesticus ) were experimentally inoculated with representative murine neuroinvasive/non-neuroinvasive strains. In both avian species, a plaque variant from Mexico that was E-glycosylation competent produced higher viremias than an E-glycosylation-incompetent variant, indicating the potential importance of E-glycosylation for avian replication. The murine non-neuroinvasive BIRD1153 strain was significantly attenuated in American crows but not house sparrows when compared with the murine neuroinvasive Texas strain. Despite the loss of murine neuroinvasive properties of nonglycosylated variants from Mexico, our data indicate avian replication potential of these strains and that unique WNV virulence characteristics exist between murine and avian models. The implications of reduced avian replication of variants from Mexico for restricted WNV transmission in Latin America is discussed.

We tested the hypotheses that mineral sites in western Oregon are used by Band-tailed Pigeons (Columba fasciata) to supplement dietary calcium and sodium. We compared mineral composition of sites used by Band-tailed Pigeons, adjacent unused sites, and three major food items during the nesting season. Sixty-five percent of used mineral sites were low in calcium (<200 ppm), whereas mean concentrations in food items were high (1,960–2,290 ppm). All but one used mineral site were high in sodium (≥678 ppm), whereas mean concentrations in food items were low (20–254 ppm). Food items were high in mean concentrations of potassium (12,470–26,980 ppm) and potassium:sodium ratios (138–656). Used and adjacent, unused, estuary mineral sites were similar in calcium and sodium concentrations. We hypothesize that because of insufficient sodium intake and inefficient sodium retention, Band-tailed Pigeons seek a sodium source to supplement their diet during the nesting season. Use of mineral sites probably depends upon sodium concentration, but also vegetation structure, development, human activity, and congregation use by Band-tailed Pigeons. Used mineral sites appear to be scarce in western Oregon, and are seemingly essential resources for this species. Eighty-six percent of known currently-used mineral sites are privately owned and subject to possible alteration from land-use practices. Mineral sites used by Band-tailed Pigeons should be included in the overall management scheme for maintaining stable breeding populations of this species.

Reliable estimates of annual harvest rates are required for the implementation of mallard (Anas platyrhynchos) adaptive harvest management decision frameworks. Because not all standard bands recovered during the hunting season are reported, band reporting probabilities are needed to estimate mallard harvest rates. Information from birds recovered with bands that notify finders of a reward (i.e., reward bands) can be used to estimate band reporting rates. We analyzed reward banding data for 3 stocks of mallards to estimate reporting probabilities that can be used to estimate harvest rates for birds recovered with toll‐free or web‐address bands. Specifically, we explored spatial variability in reporting probabilities, and assessed whether reporting probabilities varied among years. Our analysis indicated that reporting probabilities varied among the 4 Flyways, eastern Canada, and western Canada and Alaska. We had difficulty interpreting temporal fluctuations and found little evidence for any meaningful trends in reporting rates between 2002 and 2010. We recommend that reporting probabilities of 0.67 in the Atlantic Flyway, 0.81 in the Mississippi Flyway, 0.70 in the Central Flyway, 0.76 in the Pacific Flyway, 0.50 in eastern Canada, and 0.57 in western Canada and Alaska be used to estimate harvest probabilities for birds recovered in these regions. © 2013 The Wildlife Society.