Return of the Crows

By Bob Sallinger, Conservation Director

Along with the steady drip of rain, one of the surest signs of approaching winter in Portland is the seasonal congregation of crows in downtown. For the better part of two decades, Portlanders have been treated to the spectacular sight of thousands of cacophonous crows converging on the downtown area in the late afternoon and early evening. The congregations increase throughout the fall and peak in the dead of winter when upwards of 15,000 crows can be found roosting downtown.

During the spring and summer, crows fan out across the landscape in small family groups to nest and raise their young. Parents are often aided by their offspring from the prior year in this effort. Most neighborhoods around Portland have a family of territorial nesting crows. In the winter, however, crows roam across the landscape to forage by day but form communal roosts in the evening. These roosts can range in size from a few dozen crows to hundreds of thousands. There are winter roosts in several locations in Portland, but by far the largest occurs in downtown.

Scientists believe that crows form winter roosts because there is safety in numbers, large numbers of birds provide warmth during the harsher winter months, and it allows for exchange of information among the crows. Roosts can occur on urban and rural landscapes. A variety of factors may attract crows to urban landscapes for roosting including warmer ambient temperatures, food subsidies provided by garbage cans and other accessible food sources, lighting, and reduced pressure from predators such as Great Horned Owls. 

While the crows are fascinating and spectacular, a congregation of this size also produces copious quantities of crow poop, presenting a challenge in high-traffic human activity areas such as the downtown transit mall. By morning, fecal matter can cover much of the streetscape including sidewalks, benches, bus stops, outdoor furniture, and awnings. While we always encourage the community to “live with wildlife,” we also work to develop ecologically responsible and humane solutions when real conflicts do occur. 

Photo by Bob Sallinger

Downtown Clean and Safe, which is responsible for keeping the downtown core area clean, has worked for many years to address challenges associated with accumulation of crow feces. Initially, they focused on sidewalk-cleaning strategies such as pressure washing and the purchase of the Poopmaster 6000, a Zamboni-like device to clean streets and sidewalks. When those strategies proved insufficient, they shifted to contracting with licensed falconers Integrated Avian Solutions to haze the crows away from a seven by ten block area as they congregate in the evening. 

A team of falconers roams the downtown area on intermittent evenings with trained Harris Hawks. The hawks make short flights to structures such as light posts and then return to the falconer’s glove. There is no direct interaction with the crows, but the strategically deployed presence of these avian predators is enough to nudge the crows out of the streetscape and down to the trees of nearby Waterfront Park where their falling poop is absorbed more or less innocuously into the grass below. 

The falconry mimics the pressures crows would face on more natural landscapes, and crow populations are doing quite well locally and nationwide. Partners in Flight estimates there are 28 million American Crows in North America and gives American Crows their lowest threat rating for both distribution and population levels. The crow roost remains in the downtown core, the roosting crow population continues to grow, and the people of Portland continue to enjoy a truly spectacular wildlife-watching event. 

In celebration of the crows, we are excited that renowned crow researcher Kaeli Swift, one of our most popular speakers in recent years, will join us for our virtual Nature Night on December 8. Please join us to learn more about these fascinating birds and take some time to check out the amazing Portland crow roost this winter.