Table 3. Comparisons of models based on different calculations for risk level, ranked by Akaike Information (AIC).

Components Included in Risk Level Calculation					Cx. pipiens complex models	Cx. tarsalis models
Temperature	Abundance	Infection	Dead Birds	Sentinel Chickens	ΔAIC	ΔAIC
Yes	Yes	Yes	Yes	Yes	(referent)	(referent)
Yes	--	Yes	Yes	Yes	-11.3*	8.1
Yes	Yes	--	Yes	Yes	31.2	-22.7*
Yes	Yes	Yes	--	Yes	13.4	18.6
Yes	Yes	Yes	Yes	--	16.6	18.1
--	Yes	Yes	Yes	Yes	17.7	18.6
Yes	Yes	Yes	--	--	39.8	42.4
Yes	--	Yes	--	--	-1.9	42.3
--	Yes	Yes	--	--	73.9	73.4

* indicates a significant improvement in model fit compared to the referent all-elements model.