Despite their important roles in biodiversity conservation, large-scale ecological monitoring programs are scarce, in large part due to the difficulty of achieving effective design under fiscal constraints. Using long-term avian monitoring in Alberta's boreal forest as an example, I evaluated several sampling designs for cost-effectiveness. Empirical parameter estimates were used in simulations that estimated power of designs to detect trend in species' populations and community metrics. The ability to detect trend with increased sample effort depended on the monitoring target's variability and how effort was allocated to sampling parameters. Integration of power and cost estimates identified two cost-effective sampling strategies: multiple within-site plots are preferable to multiple within-year surveys for decreasing sample error; and, many sites should be sampled relatively infrequently rather than sampling few sites frequently, although importance of frequent sampling increases for variable targets. To facilitate cost-effective monitoring of biodiversity, this analysis must be extended to additional taxa.