Table 1.

Host utilization (feeding preferences from equation 3), U, West Nile virus seroprevalence, (fraction of hatch-year birds with antibodies, sampled in mid-July to early October, 2004–2008), S, estimated infective bites (using equation 4), I, and calculated mortality ratios (using equation 5). Values in parentheses are the standard error of the estimate. Ranges in parentheses for Mortality ratios are 95% confidence intervals.

	Feeding preferences			Seroprevalence			Infective bites			Mortality ratios
Site	C. wren	T. titmouse	N. cardinal	C. wren	T. titmouse	N. cardinal	C. wren	T. titmouse	N. cardinal	Wren/Cardinal	Titmouse/wren	Titmouse/Cardinal
Foggy Bottom, DC	0.93 (0.06)		2.96 (0.10)	0.25 (0.15)
Fort Dupont Park, DC	0.20 (0.06)	1.28 (0.14)	0.74 (0.10)	0.25 (0.04)	0.03 (0.03)	0.48 (0.05)	0.52 (0.09)	0.03 (0.03)	3.28 (0.35)	1.74 (0.5– 6.1)	100.40 (20.1 - )	174.32 (36.4 - )
Bethesda, MD		1.77 (0.17)	0.21 (0.06)	0.12 (0.06)	0.00*	0.23 (0.04)	0.17 (0.09)	0.00	0.46 (0.07)			>181.8* >(5.2- )
Takoma Park, MD			1.47 (0.17)	0.19 (0.08)	0.00	0.56 (0.04)	0.34 (0.14)	0.00	6.53 (3.5)
National Mall, DC	8.90 (0.17)		1.76 (0.08)
Rock Creek Park, MD	0.87 (0.20)	1.52 (0.25)	0.51 (0.14)	0.12 (0.05)	0.03 (0.02)	0.15 (0.03)	0.16 (0.07)	0.03 (0.02)	0.23 (0.04)	2.41 (0.6 – 15.8)	8.57 (1.28 - )	20.67 (5.2 - )
Baltimore, MD	7.08 (0.20)		2.15 (0.12)

^*Seroprevalence for this species at this site was zero (0.49), so the mortality ratio is .

We estimated the mortality ratio assuming one of the 49 titmouse had been seropositive and expressed the results as a minimum estimate.