A murder in the city. Well, not quite. I am, of course, referring to the popular collective noun for groupings of crows: a murder of crows.
On winter evenings in downtown Portland, Oregon, the city’s skyline doesn’t simply darken with dusk, it becomes the backdrop for one of North America’s most spectacular urban wildlife gatherings.
- “They produce 7 tonnes of guano – nightly”: Romans in biohazard suits are facing a relentless rain of oily poop
- “They’re like giant airships crossing the city.” This monumental gathering may be the world’s most incredible natural spectacle
As night falls, thousands upon thousands of the birds wheel and caw above the streets, settling into trees, rooftops and bridge trusses.
In some years, counts have exceeded 22,000 birds every night. It’s a corvid congregation of almost mythic proportions.
The species here is the American crow, a common bird throughout North America that is halfway in size between Europe’s jackdaw and carrion crow.
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Portland’s crow problems started in 2014, when the roosting populations of the birds, attracted into the city’s downtown areas by the abundance of waste food and warmer night-time temperatures, exponentially increased to more than 10,000 individuals.
Portlanders found the phenomenon both awe-inspiring and, depending on one’s tolerance for aerial poo, profoundly inconvenient. Sidewalks and storefronts beneath the vast roosts were covered in droppings – an olfactory and hygienic challenge that has taxed the city’s public works teams.
Sidewalk-cleaning machines such as the celebrated Poopmaster 6000 have come and gone, never quite keeping pace with what sometimes feels like an avian tidal wave.
But it seems the Portlanders are never short of creative solutions and found an answer that is part practical management and part theatre, with trained Harris’s hawks patrolling the skies above the city as dusk gives way to night.
Under the watchful guidance of Bird Alliance of Oregon, the ‘crow patrol’ was born. Licensed falconers now stalk the night streets, sending their birds into the trees to disperse the crows.
Falcons and hawks have been allies to humans for millennia, tamed for falconry long before the rise of skyscrapers and city councils. In its natal range from southern North America into South America, Harris’s hawk is one of the very few raptor species that hunts socially.
As a falconer’s bird, it has a good temperament, and possesses good night vision, too. The hawks do not physically attack the assembled crows, but their very presence dissuades the corvids from hanging around.
Crows are intelligent birds and the Harris’s hawks play out their ecological role, prompting the crows to move and seek safer roosting sites away from busy pavements.
Yet this solution, humane as it is, also underscores something essential about our modern relationship with nature. Crows are not pests in the way that rodents or invasive starlings might be.
They are clever, deeply social birds and their gatherings in Portland have been described more as a community than a nuisance, a vociferous coming together worthy of admiration.
That said, the practicalities of city life – clean pavements, unhindered foot traffic and safe public spaces – all demand management.
The Harris’s hawk activity doesn’t eradicate the crows. Ornithologists have noted that the birds often return once the falconry pauses, or that they simply shift their roosts to neighbouring parks.
Indeed, the practice doesn’t reduce the overall number of crows. Maybe the answer is far simpler. Clean
up our cities.
