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Results are qualitatively similar when was set equal to 0��98 or 1, so we left equal to 1 for model selection (Burnham & Anderson 2004). We evaluated these adult models as above for the age models but used AICc values http://www.selleckchem.com/products/pd-0332991-palbociclib-isethionate.html instead of QAICc values. We considered models including at most two of the covariates potentially underlying the interannual variation in survival because we felt it prudent to limit the number of candidate models given the limited number of years and the sample sizes in some years. Annual variation in crossbill population size may be attributable to demographic variables other than annual survival. For example, population declines could be explained by declines in fecundity. During the course of regular fieldwork, we recorded the number and sex of adults and number of juveniles between 2001 and 2006. Because there was a seasonal peak in the juvenile/female ratios, we estimated annual fecundity as the maximum semimonthly ratio of juveniles to adult females observed during a year. We evaluated evidence for consistent http://www.selleckchem.com/products/Trichostatin-A.html changes in fecundity by fitting a least-squares linear regression through these annual maxima. We used a simple life-table analysis to estimate projected changes in density in response to variation in annual adult and juvenile survival. Annual adult survival was set at 0��68 (the mean of annual apparent survival before 2004), juvenile survival at 0��14 and the number of female offspring produced per adult female was set at 2��4 so that the finite rate of population growth (��) equalled 1 (i.e. the population would be stable). Model-averaged yearly adult and juvenile survival rates were then used to estimate annual �� values to project successive changes in population density while keeping female fecundity constant. The confidence intervals for the projected population densities were based on the 95% confidence intervals associated with each year��s annual adult survival (��) estimates. Predicted density at year t?+?1 is based on observed density at year t to avoid propagating the error from one estimate over subsequent density estimates. Crossbill densities declined by 63% from 281 to 104 birds per km2 between 2003 and 2008 (Fig.?1; r?=??0��985, P =0��0003). Models with age-class structure for �� and p were overwhelmingly favoured over single age-class models (��QAICc?>?258). Results http://www.selleck.cn/products/ve-822.html indicate that recapture rates differed between juveniles and adult crossbills and vary year-to-year among individuals banded as adults or as juveniles (Table?1). Three of the top four models receiving the most support (��QAICc?