Cooper’s Hawks Make Themselves at Home

(Exciting news for Seattle. Cooper’s Hawks have settled in, building nests in parks and greenbelts throughout the city. The much disputed Cheasty Greenspace is now on record as having the most productive nest in the city, with 22 fledglings in the last five years. Another important reason to preserve these spaces for passive use, wildlife and scenic beauty. Read more in this guest post by Ed Deal.)

2016 SEATTLE COOPER’S HAWK PROJECT SUMMARY

Dear Cooper’s Hawk nest neighbors and friends,

This was another busy year for the study. I again logged over 700 site visits between February and mid-August. In addition, 9 other volunteers contributed several hundred additional site visit reports. Special thanks to all of them for their work!

The study has three main goals. First, we try to census the city of Seattle and establish how many Cooper’s Hawk nests exist each year. This year we located 41 nest-building pairs, of which 39 progressed to egg-laying. Of those, 35 nests successfully produced fledglings. The nesting density computes to one nest for every 2.05 square miles.

Second, we record nest productivity, counting the fledglings at each site. This year we documented 125 young that lived to fly (plus 5 more that didn’t).

Third, myself and my study partner, Martin Muller, 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 females and purple bands on males. Over the last year our color bands have been sighted at Freeland on Whidbey Island(two), Burlington in Skagit Co., and Duvall, Bellevue and Kirkland in King Co., as well as numerous locations in Seattle. Last Fall we had an amazing first out of state band sighting in Oakland, CA. This season we color-banded 31 youngsters and 4 adults. Over the last 5 years we have color-banded 183 birds. We have 131 subsequent sightings on 62 different birds, an excellent return rate of 34%.

The most popular choice of nest tree was again Big Leaf Maple (20), followed by Douglas Fir (12), W. White Pine (5), Madrona (2), E. White Pine (1), Alder (1), Atlas Cedar (1), Cottonwood (1), Horse Chestnut (1), Plane (1), and Unknown (3). This includes several pairs that built 2 nests.

Most nest sites are located in parks and greenbelts owned by the City of Seattle (29), followed by private yards (11) and a private golf course (1).

This was the 5th year of Cooper’s Hawks nesting in the current location of the Cheasty Greenbelt, producing 22 fledglings (most productive nest in the city for that 5 year period). In 2010-2011 they nested a mile further north on the west side of Cheasty Blvd, in an area we call North Cheasty….not sure what the official name is …….before that is unknown. Also, one of this year’s banded youngsters already had a fatal window hit near Freeland on Whidbey Island, 52 km from Cheasty….and just 6 weeks after fledging.

This year we had a day-long visit from Prof. Ralph Buij, a raptor biologist from Holland, who was keen to see Cooper’s Hawks, which don’t occur in Europe. We were able to show him several active nest sites and two birds in the hand.

We recently learned our report on observations of female choice in courtship behavior was accepted for publication by the prestigious Journal of Raptor Research.

I want to thank all of you for your phone calls and emails. I especially want to express my appreciation to the property owners who allowed us access to nests and banding opportunities on their private property.

I welcome your questions, and look forward to working with you all next year. We will start surveying for courtship and nest-building activity in February 2017.