Anna’s Hummingbird was first reported in Oregon in 1944. The first specimen wasn’t collected until 1966. But today, this species is a common year-round resident in western Oregon. They winter as far north as coastal British Columbia, and have even successfully wintered in central Oregon, where they get actual winter weather.
What has caused this rapid range expansion to the north? Climate change is having a measurable effect on some species, but Anna’s Hummingbird has undoubtably been helped along by the presence of bird feeders and exotic winter-blooming plants. While most of a hummingbird’s nutrition comes from the insects he eats, a reliable source of calories provided by a feeder of sugar solution can enable a bird to survive episodes of severe winter weather that would prove fatal without this supplemental food source. A higher winter survival rate provides more birds to breed in the spring, thus establishing the species in new areas.
Bird feeding is credited with helping other species expand their ranges. Northern Cardinal is a prime example in this country. In England, bird feeding is reportedly changing the evolution of one species. The European Blackcap historically migrated to Spain for the winter. With the increasing popularity of bird feeding, this species has stopped migrating south, opting instead to winter in the UK. In just 50 years, the bird has developed shorter wings (longer wings are useful in migration) and a narrower bill (better suited to eating out of bird feeders). These British birds are well on their way to becoming a new species. Read the story here.
Ethical Birder 
Hello! I found your comments on the Anna’s Hummingbird interesting. I have been searching for a history of the Anna’s Hummingbird, and have had fruitless results so far. What source told you the hummingbird was first reported in Oregon in 1944 and collected in 1966? Thank you for your help!
My information comes from Birds of Oregon; A General Reference, edited by Marshall, Hunter, and Contreras; published by Oregon State University Press. It is considered the definitive reference for the status and distribution of birds in Oregon.