Effects of telomere length on survival
Average first-year survival from fledging to recruitment was 29% and maximum recorded lifespan was 5.7 years with a mean of 152±11 days (n =566). There was a positive effect of tarsus length on first-year survival (i.e. recruitment probability) that was present in four out of five models with ∆AICc<2 (model ranked 1: odds ratio (OR )tarsus =1.27, CI=[1.04, 1.57], Table 4). In addition, there was weak evidence for a curvilinear effect of tarsus length on first-year survival present in the best model (ORtarsus^2 =1.08, CI=[0.99, 1.67]), indicating higher recruitment probability for individuals both smaller and larger than the average. The third-best model (∆AICc=1.5) suggested that the positive effect of tarsus length on first-year survival was stronger in the high population compared to thelow population (ORlow*tarsus =0.71, CI=[0.41, 1.18]), but the effect was uncertain. In addition, there was an uncertain negative effect of TL present in one model (model ranked 5, ∆AICc=1.9, ORTL =0.89, CI=[0.51, 1.53], Table 4).
The Cox proportional hazards regression analyses of long-term survival revealed a negative effect of tarsus length on the risk of death (hazard ratio (HR )tarsus =0.91, CI=[0.84, 0.99], Tables S2.3 and S2.4, Fig. 6a). In addition, two out of four models with ∆AICc<2 showed weak evidence for a curvilinear effect of TL on mortality (HRTL^2 =0.73, CI=[0.51, 1.04]), indicating a bimodal pattern, where fledglings with both short and long TL have lower long-term mortality rates (Fig. 6b, Table S2.4). The curvilinear effect of tarsus length present in two out of four models with ∆AICc<2, was uncertain and weak, i.e. close to 1 (HRtarsus^2 =0.98, CI=[ 0.95, 1.01]).