Table 1. Ranking of six general linear models relating temporal trends in nest success of dabbling ducks as a function of latitude, longitude of study site, country (Canada vs. United States), and year of study between 1935 and 2006. n = sample size; K = number of parameters; AICc = Akaike’s Information Criterion, corrected for small sample sizes; ΔAICc = the difference in AICc between each model and the model with the minimum AICc; w = Akaike weight; and r² = the proportion of the total variation in nest success explained by each model (Xu 2003).

Model Fixed effects -2*LL n K AICc ΔAICc w r²
1 Latitude Longitude 248.6 507 4 -489.0 26.8 0.00000 0.06
2 Latitude Longitude Country 253.0 507 5 -496.0 19.9 0.00003 0.08
3 Latitude Longitude Country Year 255.6 507 6 -499.0 16.9 0.0001 0.09
4 Latitude Longitude Country Year Country*Year 263.0 507 7 -511.7 4.2 0.07 0.11
5 Latitude Longitude Country Year Year² 264.7 507 7 -515.2 0.6 0.39 0.12
6 Latitude Longitude Country Year Year² Country*Year Country*Year² 267.1 507 9 -515.8 0.0 0.54 0.13