Species Composition/Population Changes

Have others noted changes in bird occurrences and/or densities in their areas?  In the 14 years I have lived here in the northern Sierra Foothills, very little increase in human population densities have occurred yet bird numbers and species have drastically changed.  Yes...we're in a drought but the changes were happening well before that manifested itself.  Western kingbirds, phainopeplas, quail, tree and cliff swallows, common when I moved here are virtually gone.  This winter I had pine siskins, Steller's jays and a couple times, evening grosbeaks at my feeders for the first time.  American goldfinches are now very rare but lesser goldfinches have increased dramatically.  In the State Park across the canyon one could find turkeys (not native...introduced) every morning in several flocks.  I rarely see or hear any in the past 5 years.  I find lots of literature on sea bird population declines but not much on the more common resident populations.

I have lived in Central Oregon since 1972 and have seen many changes. Porcupines and Jack rabbits used to be common (way to common) and they are almost gone (more than just cycle), the hares were the prey base for many predators, so they have been impacted. Pinyon Jays are now common as are Western Scrub Jays (rare before), Stellar Jays while still common have been displaced by scrub jays, Clark's nutcrackers seem to be on a downward spiral (White Bark Pine dependent?). Cougars are more common (no dog hunting) and roam the streets at night looking for town deer. Bobcats thanks to the fur trade are far and few between. A positive note has been the comeback of the alpine red fox (now called Sierra Nevada fox). Between disease and the big snows of '92, mule deer populations are 10% of previous but Elk are now quite common. Wolverines may be gone (I may have seen the last one while working at our local ski resort in '72). Crows didn't exist and are now common, along with collard doves. Peregrine falcons are common as well as merlins in winter (some spotted in summer so we may have a breeding population). I could keep going, nature is pretty dynamic and responds to all pressures.