Yo Tweets,

We recently completed the eighth year of our long-term population study of Seattle's urban-nesting Cooper's Hawks. This study builds on the 2003-2011 pioneering work of Jack Bettesworth.

Our study has three main goals. First, we census within the 83.9 square mile city limits of Seattle and try to establish the number of Cooper's Hawk nests (a nearly hopeless task). This year we found 56 pairs engaged in courtship and nest building. A record seven pairs failed during nest building, (one banded female was hit by a car); the other six disappeared, perhaps due to the death of a mate or sneaking off to alternate nests we never found. Forty-nine pairs went on to incubate eggs. Three sites failed during incubation. A record high of 46 pairs successfully produced fledged young (next-highest record was 40 pairs in 2018).

Second, we count how many fledged young each nest produces. This year we documented a record 174 young that lived long enough to fledge, an outstanding productivity of 3.78 young per successful nest.

Third, we attempt to put unique color-ID bands on as many birds as possible. This allows us to track individual birds as they move around the city and beyond. We put orange bands on the right legs of females and purple bands on the left legs of males. Each band has a unique combination of stacked alphanumeric symbols. Over the past year, our bands have been sighted in Kirkland, Freeland (Whidbey Island), Normandy Park, Edmonds, and in many locations in Seattle. This season we color banded 46 youngsters and 1 adult. Over the last eight years we have color banded 279 birds, with 226 subsequent sightings on 99 different birds, a return rate of 35%. The vast majority of sightings are in Seattle (190) or non-Seattle parts of King County (24), indicating a non-migratory population.

Once again, the 56 pairs of nest-building Coops picked a diverse list of nest tree species. Perennial favorites were well-represented: Big Leaf Maple (28), Douglas Fir (11), White Pine (7), and Alder (5). Three new species were added to the list: Ponderosa Pine, Sequoia, and Eucalyptus. Two pairs built three nests and 13 pairs build two nests, for a total of 73 nests. Most nest sites are in City of Seattle parks and greenbelts (37), followed by private property (14), cemeteries (3), and UW (2).

These 56 nest-building pairs should be considered the MINIMUM number in the city. Several potential nesting areas are nearly impossible to search because of safety concerns and terrain (e.g., the steep trail-less overgrown greenbelt along the railroad north and south of Golden Gardens, several parts of the extensive West Duwamish Greenbelt, and the tent camps on the wooded hillside of Beacon Hill along I-5). Our known nesting density in Seattle is one pair for every 1.5 square miles.

We owe special thanks to each of the volunteers and observers who helped to collect this information. This would have been an even more impossible task without their hard work.

We greatly appreciate any color ID band readings from Tweeterdom, especially you digiscopers!

Ed Deal

Seattle Cooper's Hawk Project

Urban Raptor Conservancy

https://urbanraptorconservancy.org/

/ https://urbanraptorconservancy.org/

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