Crows in Portland, Oregon

There is a large population of crows in the American city of Portland, Oregon.^[1] 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".^[2] There are also fewer predators in downtown Portland.^[3] The crow population in Portland can reach as high as 15,000 to 23,000.^[2][4][5][6] The population has increased in the last decade.^[7]

There is a seasonal pattern to the crow roosting.^[8][9] 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).^[10]

The Portland Crow Roost is a project to count and document the roosting locations of the local crow population.^[11][12]

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.^[2] The city has a small team of falconers who use hawks to move crows out of a focused 72-block radius.^{[13][5][14][15]}