The key demographic parameters of a population of Hyacinth Visorbearer, Augastes scutatus, an endemic hummingbird of the mountaintops of southeastern Brazil, are described for the first time. The study was conducted in the Alto do Palácio region, in the Serra do Cipó National Park, southeastern Brazil. Monthly, from August 2007 to July 2009, the Hyacinth Visorbearer individuals were captured in mist nets and banded. Using mark-recapture data, we modeled monthly apparent survival (φ;) and capture probability (p), with sex and time (month) as covariates. We considered two time-since-marking (TSM) models among candidate models to control for the possible effect of transient individuals on parameter estimates. The two best-supported models (gaining 74% of summed Akaike weight) included effects of transient birds on monthly survival, with constant capture probability. The model-averaged apparent survival estimates for the first month after capture (φ;¹) were considerably lower than the values for the second and later months following capture (φ;² ). The apparent monthly survival showed difference between sexes, with females' value (φ;² = 0.93 ± 0.03) slightly higher than males' value (φ;² = 0.90 ± 0.03). These differences translated into distinctly higher annual survival of females (0.418 ± 0.16) than males (0.318 ± 0.12). The estimated annual capture probability was high (75%). We strongly suggest that TSM effects should be evaluated in future humming bird population studies.