A Deluge of Cooper’s Hawks

by Bob Sallinger, Conservation Director

The heat dome that blanketed Portland at the end of June brought an unprecedented influx of animals into our Wildlife Care Center. We set an all-time record for intakes between June 24 and July 3 as temperatures soared to historic heights. During this period, 622 animals came in for care, representing nearly 17% of the intakes we would typically see in an entire year. While many species were affected by the scorching heat, Cooper’s Hawks seemed to be particularly hard-hit—a stunning 110 young Cooper’s Hawks passed through our door during that time period in a phenomenon that some staff and volunteers began referring to as “hawkpocalypse” and that we are still trying to understand.

Juvenile Cooper's Hawk perched on leafy branch looking off
A handsome Cooper’s Hawk fledgling perched in a tree, looking around inquisitively. Photo by Fern Wexler.

Heat waves often bring influxes of animals to our facility, especially during nesting season. Extreme hot weather can be particularly hard on young birds. Crowded nests grow hot and uncomfortable for their occupants, or cavities exposed to direct sunlight can turn into ovens. Parents, affected by the heat themselves, may spend less time at the nest and feed less often, reducing fluid intake for their nestlings. Fledglings learning to fly may have limited ability to escape from the baking ground. It is no surprise that more birds and especially young birds arrive at our doors during hot weather.

However, we have never seen anything like the deluge at the end of June. For days, a line of people holding boxes of animals stretched across our parking lot. Volunteers at our makeshift intake table, set up outdoors to comply with COVID-19 protocols, distributed clipboards, explained intake procedures, and tried to expedite what seemed like an endless stream of patient people waiting under the scorching sun. Our intake room rapidly reached capacity and overflowed into our lobby. And still the animals kept arriving.

While this event was extraordinary, Cooper’s Hawks in particular stand out. These hawks nest throughout our urban landscape, including in the urban interior. They build stick nests in tall trees and often hunt at backyard feeders. If you see a hawk flying low through a neighborhood, it is likely a Cooper’s Hawk.

Like many species, they were well into their nesting cycle when the heat dome struck. Of the Coops brought to our Care Center, almost all were within a week of being able to fly and had been found on the ground, often in parks but also in yards, parking lots, and right-of-ways. The majority were suffering from dehydration and other impacts from the heat. Of the 110 Cooper’s Hawks we took in, we were able to hydrate and treat 64, which we eventually returned to their site of origin to continue being cared for by their parents. Another 19 were held for longer-term rehabilitation and release, but 27 were beyond our ability to save.

Numerous wildlife rehab centers around the Northwest reported a steep increase in intakes during the heat dome. Some also noted exceptionally high numbers of Cooper’s Hawks, while others highlighted additional species that seemed particularly hard-hit. In Seattle, the PAWS Wildlife Center reported dozens of injured young Caspian Terns from a nesting colony on the rooftop of an industrial building. The unflighted nestlings were injured as they tried to escape the broiling rooftop and plunged to the pavement below.

What we see at rehabilitation centers is the tip of the iceberg, a sample of what is happening out on the landscape. However, the lessons and questions raised by the heat dome are daunting. How many birds perished? The seemingly exceptional impact on Cooper’s Hawks in Portland serves as a reminder of how much we don’t know about the potential impacts of climate change. While we might expect Cooper’s Hawks to be affected like other birds, there is nothing to suggest that they would be exceptionally vulnerable. Why were Cooper’s Hawks so hard-hit in this event? The heat dome has been described as a “once-in-a-thousand-years” event, but we know that with the accelerated effects of climate change, the unprecedented is becoming the norm.