Supplementary Information
Cross-environmental individual correlation
All traits were significantly correlated on the individual level between seasons (Table S1). That is, individuals with a high value for any of the traits considered in this study in, say, the breeding season, also had a high value for this trait in the winter season. Tarsus length, activity, IgG concentration and breathing rates showed particularly high (≥0.90) individual-level correlations between seasons.
Mixed-model effects associated with the personality and physiological traits
From the multivariate analysis on the six traits we found associations of several fixed effect variables with each of the traits (Table S2). For all traits we found that there were differences between years for these traits, although the annual differences were small. We found sexual dimorphism in the trait handling aggression, where females were less aggressive than males; this has also been found in nestlings in this population (Brommer and Kluen 2012). For the trait haematocrit, we found that females tend to have a slightly lower haematocrit level than males. We found significant associations of age of the birds and the traits activity and handling aggression. Old (> 1 year old = 3rd calendar year (cy) or older) birds were more active in the cage and less aggressive during measuring in the hand than yearlings (1 year old = 2nd cy birds). Time of the day was significantly associated with all traits apart from activity. However, the effect size of this variable (giving the change in trait value hour–1) was for all traits very small. Season was significantly associated with all traits, apart from handling aggression. For the trait activity we found that birds were less active in the cage during the winter season than in the breeding season. The effect size of this variable is quite strong. Possibly birds are less active in the winter in the cage due to the low temperatures, short days and uncertain food stocks, thus a more conservative energy expenditure can be beneficial for survival in this season. Breath rate during winter seasons was higher than in the breeding season, possibly due to higher metabolic rates in the winter (Gill 1989; Swanson and Garland 2009). For the two physiological traits we found a reduced IgG-level and haematocrit for birds measured in the winter compared to the breeding season. Both behavioural traits measured in the hand (handling aggression and breath rate) were affected by an observer effect, although not in a consistent direction. Differences between observers could stem from differences in experience with the measuring of the traits, from a difference in response of the birds to the observer, or a combination of these two. The variable ‘total blood’ was significantly associated with haematocrit value; however, its effect size was very small, and likely reflects a higher precision in measuring larger volumes of blood.
Literature cited only in the supplement
Gill FB (1989) Ornithology. WH Freeman and Company, New York
Swanson DL and Garland T Jr (2009) The evolution of high summit metabolism and cold tolerance in birds and its impact on present-day distributions. Evolution 63: 184-194
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Table S1Summary statistics of mixed model analysis estimating season-specific between-individual and residual variances and the individual-level covariance between seasons. Traits measured are detailed in the main text. Mixed models included the fixed effects given in Table S2 and outlined in the Material and Methods of the main text. Presented are the phenotypic variance (VP) for each season and the repeatability (R) per season of each trait. The individual-level correlation (rI) between seasonsis givenforeach trait, and a LRT statistics tested with 1 degree of freedomprovided a probability value (P) of this correlation being equal to zero. Standard errors of the estimates are calculated following the delta method
Trait / VP Breeding / VP Winter / R Breeding / R Winter / rI (Br, Wi) / LRT / PTarsus / 0.21 ± 0.014 / 0.19 ± 0.016 / 0.94 ± 0.008 / 0.84 ± 0.035 / 0.95 ± 0.03 / 101.2 / 0.0000
sqrt Activity / 1.3 ± 0.090 / 0.94 ± 0.084 / 0.34 ± 0.092 / 0.15 ± 0.13 / 0.98 ± 0.57 / 7.2 / 0.0071
Log(IgG) / 0.094 ± 0.0054 / 0.096 ± 0.0088 / 0.18 ± 0.07 / 0.36 ± 0.13 / 0.90 ± 0.40 / 4.7 / 0.0296
Haematocrit / 1.2E-3 ± 7.2E-5 / 8.5E-4 ± 7.5E-5 / 0.26 ± 0.07 / 0.36 ± 0.11 / 0.56 ± 0.26 / 5.8 / 0.0164
Handling aggression / 0.97 ± 0.059 / 0.94 ± 0.085 / 0.47 ± 0.059 / 0.49 ± 0.098 / 0.48 ± 0.19 / 6.5 / 0.0105
Breath rate / 0.12 ± 0.0072 / 0.11 ± 0.010 / 0.27 ± 0.07 / 0.36 ± 0.12 / 0.93 ± 0.29 / 13.3 / 0.0003
Table S2 Random and fixed effect parameter estimates from a multivariate model with all six traits as dependent variables.The estimated variance as well as the proportion of the REML phenotypic variance is given for the residuals and for the random effect (bird ID). The adjusted repeatability (i.e. repeatability based on REML variance components when fixed effects are included) for each of the traits is the proportion of between- individual variance (VI) over the total phenotypic variance (VI + VR), where (VI + VR) is denoted as the REML phenotypic variance in the Table. The model structure included the covariances between these traits and these are reported as correlations in Table 2. Variable ‘year’ is given in contrast with year 2007-2008. Variable ‘sex’ is given in contrast with ‘male’. Variable ‘age’ is given in contrast with ‘1-year old’. Variable ‘season’ is given in contrast with ‘breeding season’. Variable ‘observer’ is given in contrast with ‘observer 1’.Fixed effects fitted to all traits were “Time” (F6,753.6 = 5.79, P<0.001), “Season” (F6,830.4 = 63.65, P <0.001), “Year” (F12,1106.6 =3.72, P < 0.001), “Sex” (F6,605.8 = 39.2, P<0.001) and “Age” (F6, 858.1 = 2.86, P =0.009). Test for other fixed effects specific to certain traits are reported in the Table below
Trait/TypeSourceEstimate ± s.e.proportion ± s.e.TestP
Tarsus lengthREML phenotypic0.210 ± 0.012
Residual0.0217 ± 0.00180.103± 0.011
RandomBird ID0.188 ± 0.0120.897 ± 0.011
FixedIntercept17.2 ± 0.032
FixedYear
2008-20090.0236 ±0.022
2009-2010–0.0034 ±0.030
FixedSex
female–0.424 ± 0.035
FixedAge
>1 yr–0.0042 ± 0.020
FixedTime of day0.00133 ± 0.0031
FixedSeason
winter–0.0604 ± 0.023
FixedObserverF3, 380.0 = 21.240.001
Obs. 20.130 ± 0.021
Obs. 30.0247 ± 0.030
Obs. 4–9.13E-4 ± 0.36E-2
sqrt ActivityREML phenotypic1.163 ± 0.065
Residual0.820 ± 0.0760.705± 0.063
RandomBird ID0.343 ± 0.0800.295 ± 0.063
FixedIntercept3.49 ± 0.141
FixedYear
2008-2009–0.123±0.12
2009-2010–0.0446 ±0.13
FixedSex
female–0.0585 ± 0.093
FixedAge
>1 yr0.215 ± 0.083
FixedTime of day–0.0199 ± 0.016
FixedSeason
winter–0.626 ± 0.11
FixedObserverF3, 640.9 = 20.00.001
Obs. 2–0.0657 ± 0.11
Obs. 30.227 ± 0.14
Obs. 40.0320 ± 0.16
Handling aggressionREML phenotypic0.960± 0.048
Residual0.600 ± 0.0470.625 ± 0.049
RandomBird ID0.361 ± 0.0560.375 ± 0.049
FixedIntercept3.60 ± 0.093
FixedYear
2008-2009–0.0532 ±0.080
2009-20100.00780 ±0.096
FixedSex
female–0.507 ± 0.076
FixedAge
>1 yr–0.171 ± 0.066
FixedTime of day0.031 ± 0.012
FixedSeason
winter–0.0332 ± 0.081
FixedObserverF3, 804.6 = 5.30.001
Obs. 2–0.182 ± 0.080
Obs. 3–0.398 ± 0.116
Obs. 4–0.166 ± 0.138
Breath-rateREML phenotypic0.118 ± 0.0060
Residual0.0786 ± 0.00610.665 ± 0.051
RandomBird ID0.0397 ± 0.00690.335 ± 0.051
FixedIntercept2.20 ± 0.033
FixedYear
2008-2009–0.0912 ±0.028
2009-20100.000286 ±0.034
FixedSex
female0.142 ± 0.027
FixedAge
>1 yr–0.0096 ± 0.023
FixedTime of day0.00467 ± 0.0043
FixedSeason
winter0.476 ± 0.029
FixedObserverF3, 802.7 = 72.8<0.001
Obs. 20.0195 ± 0.028
Obs. 3–0.0544 ± 0.041
Obs. 4–0.37 ± 0.051
log IgREML phenotypic0.0942 ± 0.0046
Residual0.0750 ± 0.00580.796 ± 0.056
RandomBird ID0.0192 ± 0.00550.204 ± 0.056
FixedIntercept5.96 ± 0.028
FixedYear
2008-2009–0.0701 ±0.026
2009-2010–0.0898 ±0.027
FixedSex
female0.0014 ± 0.023
FixedAge
>1 yr0.0090 ± 0.021
FixedTime of day0.00508 ± 0.0039
FixedSeason
winter–0.194 ± 0.025
HaematocritREML phenotypic0.00114 ± 0.56E-4
Residual8.64E-4 ± 6.3E-50.755 ± 0.049
RandomBird ID2.80E-4 ± 6.1E-50.245 ± 0.049
FixedIntercept0.520 ± 0.003
FixedYear
2008-2009–0.0120 ±0.0028
2009-2010–0.00636 ±0.0029
FixedSex
female0.0109 ± 0.0026
FixedAge
>1 yr0.0047 ± 0.0023
FixedTime of day–0.00152 ± 0.00042
FixedSeason
winter–0.015 ± 0.0027
Fixedtotal blood0.000068 ± 0.00002F1, 875.3 = 7.420.007
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