Monitoring survival rates of Swainson's Thrush Catharus ustulatus at multiple spatial scales

We estimated survival rates of Swainson's Thrush, a common neotropical, mig ratory landbird, at multiple spatial scales, using data collected in the we stern LISA from the Monitoring Avian Productivity and Survivorship Programm e. We evaluated statistical power to detect spatially heterogeneous surviva l rates and exponentially declining survival rates among spatial scales wit h simulated populations parameterized from results of the Swainson's Thrush analyses. Models describing survival rates as constant across large spatia l scales did not fit the data. The model toe chose as most appropriate to d escribe survival rates of Swainson's Thrush allowed survival rates to vary among Physiographic Provinces, included a separate parameter for the probab ility that a newly captured bird is a resident individual in the study popu lation, and constrained capture probability to be constant across all stati ons. Estimated annual survival rates under this model varied from 0.42 to 0 .75 among Provinces. The coefficient of variation of survival estimates ran ged fi om 5.8 to 20% among Physiographic Provinces. Statistical power to de tect exponentially declining trends was fairly low for small spatial scales , although large annual declines (3% of previous year's rate) were likely t o be detected when monitoring was conducted for long periods of time (e.g. 20 years). Although our simulations and field results are based an only fou r years of data from a limited number and distribution of stations, it is l ikely that they illustrate genuine difficulties inherent to broadscale effo rts to monitor survival rates of territorial landbirds. In particular our r esults suggest that more attention needs to be paid to sampling schemes of monitoring programmes, particularly regarding the trade-off between precisi on and potential bias of parameter estimates at varying spatial scales.