Landbirds in the Nortwest parks include some species that live here year-round and others spend only a portion of the year as migrants. Because birds are sensitive to suble changes in weather, plant comuitiies, and food supplies, their populations are good indicators of ecosystem condition. Birds are monitored in the spring to early summer breeding season when they are most noticeable and most reliably counted. Our teams perform statistically rigorous counts locating the birds by sight and sound and tallying their changing numbers over time.