Based on 3,202 research-grade iNaturalist observations in Oregon, Brewer's Blackbird is most often recorded in May; in Oregon it behaves like a seasonal. It ranks #34 among birds recorded in the state in our data.
Euphagus cyanocephalus
Brewer's Blackbird in Oregon by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in Oregon in May

Mallard

American Robin
Canada Goose

Black-headed Grosbeak
Red-winged Blackbird

Bald Eagle

Great Blue Heron

Song Sparrow
Places to look in Oregon
National ForestWillamette National Forest
Mount Hood National Forest
National ForestDeschutes National Forest
Hoyt Arboretum
Leach Botanical Garden
Umatilla National Forest
FAQ
When does Brewer's Blackbird appear in Oregon?
Mainly March–October, with the most records in May.
How common is Brewer's Blackbird in Oregon?
It ranks #34 by number of iNaturalist observations among birds in Oregon (3,202 records in our sample).