Table S1 Model-selection results for the presence of long-term trends in Song Sparrow survival rates. Survival () a) Adult survival RefA + T + T2 + Winter Tempd + Rain RefA + T + T2 Reft RefA + T RefA b) Juvenile survival Reft RefJ + T RefJ + T + T2 RefJ k AICc 69 67 95 66 65 8370.01 8379.18 8383.72 8391.67 8392.09 95 65 66 64 8383.72 8386.70 8386.91 8392.25 ΔAICc w Dev R2Dev 0.00 9.17 13.71 21.66 23.08 0.989 0.010 0.001 0.000 0.000 1470.13 1483.42 1430.02 1497.97 1501.45 0.44 0.25 1.00 0.05 – 0.00 2.98 3.19 8.53 0.694 0.156 0.141 0.010 1430.02 1495.06 1493.21 1502.66 1.00 0.10 0.13 – Notes: Linear (T) and quadratic (T2) trends in survival were added to the baseline reference model for each age class (RefA and RefJ, respectively) and compared to Reft, the primary reference model with full year-dependent survival (Table 2a). There was strong support for a quadratic trend in adult survival, so we fit another model to determine whether the strong support for an effect of winter weather on adult survival (Table 2b) was due solely to similar quadratic trends in adult survival and winter average temperature (Fig. 1a). The final model included both the quadratic trend in survival and the de-trended winter average temperature (subscript d). Table S2 Model-selection results for the difference in effects of weather on adult and juvenile survival. Survival () k AICc Age * (Winter Temp + Rain + Wintert-1 Temp + Rain2) Age + (Winter Temp + Rain + Wintert-1 Temp + Rain2) Reft 44 39 95 8362.59 8379.42 8383.72 ΔAICc 0.00 16.83 21.13 w Dev 1.000 0.000 0.000 1513.92 1540.92 1430.02 Notes: Our model-selection process identified support for a direct effect winter weather on adult survival and an indirect effect of prior winter weather on juvenile survival (Table 2). These results suggest either that these variables had different effects on each age class, or that the effects were similar but that there was more uncertainty in the effect on one of the age classes. To help distinguish between these possibilities, we compared the fit of two models that combined these effects. The first allowed effects of each variable to vary by age class, while the second constrained the effect of each variable to be the same for each age class. Table S3 Model-selection results for the effects of age, year, weather, and density on survival. Survival () Recapture (p) k AICc a) Effects of age and year Reft = At + Jt t 95 8383.72 At + Jt 1 64 8391.71 RefJ = At + J t 64 8392.25 RefA = A + Jt t 65 8393.09 At + J mt 96 8409.66 At + J 1 33 8416.78 At + Jt mt 127 8417.65 A + Jt mt 97 8418.05 A + Jt 1 34 8433.04 b) Effects of weather and density on adult survival RefA + Winter Temp + Rain 67 8365.87 2 RefA + Winter Temp + Rain 68 8367.61 RefA + Winter Temp + Rain2 68 8367.92 2 2 RefA + Winter Temp + Rain 69 8369.63 Reft 95 8383.72 2 RefA + Density 67 8384.67 RefA + Summer Temp 66 8387.77 2 RefA + Summer Temp 67 8389.66 RefA + Wintert-1 Temp + Rain 67 8390.79 2 RefA + Wintert-1 Temp + Rain 68 8392.36 RefA + Wintert-1 Temp2 + Rain 68 8392.48 RefA 65 8393.09 2 2 RefA + Wintert-1 Temp + Rain 69 8393.98 RefA + Density 66 8394.54 c) Effects of weather and density on juvenile survival RefJ + Wintert-1 Temp + Rain2 67 8378.12 2 2 RefJ + Wintert-1 Temp + Rain 68 8380.11 Reft 95 8383.72 2 RefJ + Wintert-1 Temp + Rain 67 8386.79 RefJ + Wintert-1 Temp + Rain 66 8387.74 2 RefJ + Summer Temp 66 8389.76 2 RefJ + Density 66 8390.08 RefJ + Density 65 8391.23 RefJ 64 8392.25 2 RefJ + Winter Temp + Rain 67 8392.85 ΔAICc R2Dev H# 1470.11 1469.79 1470.10 1469.76 1430.02 1488.91 1494.07 1493.90 1493.90 1495.03 1494.55 1501.45 1494.12 1500.83 0.44 0.44 0.44 0.44 1.00 0.18 0.10 0.11 0.09 0.10 0.10 – 0.10 0.01 H2 H2 H2 H2 – H4 H1 H1 H3 H3 H3 – H3 H4 1482.36 1482.29 1430.02 1491.03 1494.04 1496.06 1496.38 1499.58 1502.66 1497.09 0.28 0.28 1.00 0.16 0.12 0.09 0.09 0.04 – 0.08 H3 H3 – H3 H3 H1 H4 H4 – H2 w Dev 0.00 7.98 8.53 9.37 25.94 33.06 33.93 34.33 49.32 0.960 0.018 0.013 0.009 0.000 0.000 0.000 0.000 0.000 1430.02 1502.11 1502.65 1501.45 1453.88 1590.47 1396.89 1460.18 1604.70 0.00 1.73 2.05 3.76 17.85 18.79 21.90 23.79 24.91 26.49 26.61 27.22 28.11 28.66 0.518 0.218 0.186 0.079 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.00 1.99 5.60 8.67 9.62 11.64 11.96 13.11 14.13 14.73 0.684 0.253 0.042 0.009 0.006 0.002 0.002 0.001 0.001 0.000 RefJ + Winter Temp + Rain RefJ + Summer Temp RefJ + Winter Temp2 + Rain2 RefJ + Winter Temp2 + Rain 66 65 68 67 8392.92 8394.29 8394.36 8394.90 14.80 16.17 16.24 16.78 0.000 0.000 0.000 0.000 1499.22 1502.64 1496.54 1499.14 0.05 0.00 0.08 0.05 Notes: Survival model notation includes effects of juvenile (J) and adult (A) age classes, with the subscript denoting year-dependent (t) or constant (no subscript) survival. Recapture models include year-dependent (t), constant (1), or an effect of time-since-marking (mt). For (bc), we added linear and quadratic effects of each variable to RefA and RefJ, the baseline reference model for each age class from (a). We present models including quadratic effects with a shortened notation, but these models do include both the linear and quadratic terms. See Table 1 for the definition of each variable and the hypothesis (H#) it represents. H2 H1 H2 H2 Figure S1 Sensitivity to missing values of the estimated effects of weather variables on (a) adult survival and (b) juvenile survival. For both age classes, we initially replaced missing weather values with zero (equivalent to the standardized mean), but we also repeated the analyses after replacing missing weather values with -2, -1, +1, and +2 (equivalent to 1 or 2 standard deviations below or above the mean). In each analysis, support was strongest for the effects of winter average temperature and precipitation on adults, and the effects of prior winter average temperature and precipitation on juveniles. Shown are the estimated effect sizes of these variables from each analysis.