There is a large population of crows in the American city of Portland, Oregon. While some of the birds are migratory, most are residents of the region. According to Bird Alliance of Oregon, crows gather along the Willamette River because there are "fewer conflicts". There are also fewer predators in downtown Portland. The crow population in Portland can reach as high as 15,000 to 23,000. The population has increased in the last decade.
There is a seasonal pattern to the crow roosting. During the fall season (August to October), crows return to the city for "pre-roost". Peak urban roosting takes places during the winter season (November to February). There is a population decrease during the spring season (March and April), before peak breeding occurs during the summer season (May to July).
The Portland Crow Roost is a project to count and document the roosting locations of the local crow population.
While the use of bird poison on public property has been banned since 2019, some dead crows have been found with the neurotoxin Avitrol in their system. The city has a small team of falconers who use hawks to move crows out of a focused 72-block radius.