Nestling entanglement.

<p>(A) Nestling with tarsometarsus entangled in mass of synthetic string; (B) nestling with legs tied together with wire (arrow indicates strictures in the bone of the tibiotarsus); and (C) carcass of nestling with legs tied together by synthetic string.</p

Percentage of each type of anthropogenic material in nests.

<p>Examples from nests are shown to right (<i>n</i> = 678 total items; 54 nests).</p

Map of study area in Davis, California, USA.

<p>All detected nests (<i>n</i> = 106) within this site were monitored for fledging success.</p

Seasonal temperature pattern within the study area.

<p>Graph showing daily mean temperatures (dark line) and – percentiles (shaded area) for the study area.</p

Data-Driven Modeling to Assess Receptivity for Rift Valley Fever Virus

<div><p>Rift Valley Fever virus (RVFV) is an enzootic virus that causes extensive morbidity and mortality in domestic ruminants in Africa, and it has shown the potential to invade other areas such as the Arabian Peninsula. Here, we develop methods for linking mathematical models to real-world data that could be used for continent-scale risk assessment given adequate data on local host and vector populations. We have applied the methods to a well-studied agricultural region of California with 1 million dairy cattle, abundant and competent mosquito vectors, and a permissive climate that has enabled consistent transmission of West Nile virus and historically other arboviruses. Our results suggest that RVFV outbreaks could occur from February–November, but would progress slowly during winter–early spring or early fall and be limited spatially to areas with early increases in vector abundance. Risk was greatest in summer, when the areas at risk broadened to include most of the dairy farms in the study region, indicating the potential for considerable economic losses if an introduction were to occur. To assess the threat that RVFV poses to North America, including what-if scenarios for introduction and control strategies, models such as this one should be an integral part of the process; however, modeling must be paralleled by efforts to address the numerous remaining gaps in data and knowledge for this system.</p></div

Seasonal mosquito abundance patterns.

<p>Realistic annual patterns for <i>Cx. tarsalis</i> and <i>Ae. melanimon</i> defined using trap data for each of the dominant land use categories within the study area. Traps collected <i>Ae. melanimon</i> only in 2 land uses, with the largest numbers occurring in seasonally flooded wetlands.</p

Study area.

<p>Map showing the location of the study area within California (left panel), and a map of the study area depicting the dominant land use within each 5-km grid cell (right panel).</p

Diagram of the model.

<p>Schematic of the SEIR model constructed for Rift Valley fever virus circulation in California. Mosquitoes are categorized as capable of vertical transmission (<i>Aedes</i>) or not (<i>Culex</i>). For <i>Aedes</i>, adult mosquitoes emerge from uninfected (P) or vertically infected (Q) eggs. Hosts are categorized as highly competent (livestock) or incompetent (dead-end hosts) for RVFV transmission. See the text for a complete explanation.</p

Spatio-temporal patterns of epidemicity, .

<p>Maps (upper panel) showing an estimate of the maximal transmission potential, , by month, and a graph of median daily values (lower panel) by land use class. Dashed lines in the lower panel indicate the and percentiles for the land use class of the same color. Wetlands and other grid cells without competent hosts (i.e., dairy cows) are mapped in gray and were not included in the analysis because transmission would not be expected in those locations. December is omitted from the maps because it did not differ meaningfully from January, with universally 1.</p

<i>Cx. tarsalis</i> abundance and host diversity.

<p><i>Culex tarsalis</i> abundance and bloodmeal host diversity at a farmstead north of Davis, CA, from May 2008 through June 2009. Shading on the x-axis depicts the presence of nesting herons and egrets at the farmstead, with arrival beginning in April and departure in late August through September. A) Lines represent abundance of host-seeking females collected in CO₂ traps at the farmstead and nearby Yolo Bypass Wildlife Area and resting females collected in the walk-in red box. Bars shows percent of total bloodmeals identified as mammalian hosts. B) Total number of utilized host species and Shannon diversity index (H′) expressed as <i>e</i>^H′. H′ increased both with increased number of hosts and the more even distribution of bloodmeals among host species.</p